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Chapter 6: Adding Images to Your Site![]() |
The book by Richard Ford, about a long uneventful weekend in the life of Frank Bascombe, a divorced real estate salesman in Haddam, New Jersey, won the Pulitzer Prize for Literature:
"Unmarried men in their forties, if we don't subside entirely into the landscape, often lose important credibility and can even attract unwholesome attention in a small, conservative community. And in Haddam, in my new circumstances, I felt I was perhaps becoming the personage I least wanted to be and, in the years since my divorce, had feared being: the suspicious bachelor, the man whose life has no mystery, the graying, slightly jowly, slightly too tanned and trim middle-ager, driving around town in a cheesy '58 Chevy ragtop polished to a squeak, always alone on balmy summer nights, wearing a faded yellow polo shirt and green suntans, elbow over the window top, listening to progressive jazz, while smiling and pretending to have everything under control, when in fact there was nothing to control."The script of Independence Day, the movie, in which aliens blow up the White House, wasn't quite as well-crafted. Yet more people went to see the movie than read the book.
People like pictures.
People like movies even better than pictures but, for most publishers, they are unrealistically expensive to produce and, for most users in 1998, they are unrealistically slow to download.
This chapter documents a method for building an image library and presenting it to each Web user in the best way for that particular person.
High-quality black-and-white photographic prints have a contrast range of about 100 to 1. That is, the most reflective portion of a print (whitest highlight) reflects 100 times more light than the darkest portion (blackest shadow). The ideal surface for reflecting a lot of light would be extremely glossy and smooth. The ideal surface for reflecting very little light would be something like felt.
It is not currently possible to make one sheet of paper that has amazingly reflective areas and amazingly absorptive areas. Magazine pages are generally much worse than photographic paper in this regard. Highlights are not very white and shadows are not very black, resulting in a contrast ratio of about 20 to 1.
Slides have several times the contrast range of a print. That's because they work by blocking the transmission of light. If the slide is very clear, the light source comes through almost undimmed. In portions of the slide that are nearly black, the light source is obscured. Photographers always suffer heartbreak when they print their slides onto paper because it seems that so much shadow and highlight detail is lost. Ansel Adams devoted his whole career to refining the Zone System, a careful way of mapping the brightness range in a natural scene (as much as 10,000 to 1) into the 100 to 1 brightness range available in photographic paper.
Computer monitors are closer to slides than prints in their ability to represent contrast. Shadows correspond to portions of the monitor where the phosphors are turned off. Consequently, any light that comes from these areas is just room light reflected off the glass face of the monitor. You would think that the contrast ratio from a computer monitor would be 256 to 1 since display cards present 256 levels of intensity to the software. However, monitors don't respond linearly to increased voltage. Contrast ratios between 100 to 1 and 170 to 1 are therefore more typical.
Most Web publishers never take advantage of the monitor's ability to
represent a wide range of tones. Rather than starting with the original
slide or negative, they slap a photo down on a flatbed scanner. A
photographic negative can only hold a tiny portion of the tonal range
present in the original scene. A proof print from that negative has even
less tonal range. So it is unsurprising that the digital image resulting
from this scanned print is flat and uninspiring.
Obtaining a high-quality scan isn't so difficult. You must go back to whatever was in the camera, that is, the original negative or slide. You should not scan from a dupe slide. You should not scan from a print. The scan should be made in a dust-free room or you will spend the rest of your life retouching in PhotoShop. Though resolution is the most often mentioned scanner specification, it is not nearly as important as the maximum density that can be scanned. You want a scanner that can see deep into shadows, especially with slides.
Never going back to the original slide or negative again means never. If a print magazine requests a high-resolution image to promote your site, you should be able to deliver a 2,000x3,000 pixel scan without having to dig up the slide again. If there is a fire at your facility and all of your slides burn up, you should have a digital backup stored elsewhere that is sufficient for all your future needs.
Quick retrieval means that if a user says, "I like the picture of the tiger in Heather Has Two Mommies (http://photo.net/zoo)," you can quickly find the high-resolution digital file.
Rather than taking up 5MB of hard disk space, which you might be tempted to scavenge when you think a Web project has been completed, a PhotoCD scan permanently resides on a CD-ROM. That means you will always have the scan available if an unanticipated need arises. If a magazine publisher decides that it must have an image, you can email the full .pcd file.
Quickly locating an image on PhotoCD is facilitated by Kodak's provision of index prints. You can work through a few hundred images per minute by looking over the index prints attached to each CD-ROM.
What does all of this cost? About $1 to $3 for a standard scan from a 35mm original; about $15 for a Pro scan from a medium format or 4x5-inch original. When you consider that you are getting 500MB of media with each PhotoCD, the scanning per se is free (in other words, it is cheaper to have a PhotoCD made than to buy a hard disk capable of storing that much data).
See http://photo.net/photo/labs.html for my current favorite PhotoCD vendors.
Suppose that a publisher has a high-resolution digital image in a large
uncompressed file. How to make this image available to Web users?
What most commercial publishers do is manually produce a single JPEG
that will fit nicely on the same page as the text, on a small monitor.
This is usually about 180x250 pixels in size. The user gets a little
graphical relief from plain text but can't extract much information from
the photo unless it is a very simple image.
At right: an example of an unlinked, and hence frustrating, thumbnail.
It is a ruin in Canyon de Chelly and users who want to see
construction details of this Anasazi dwelling won't get any help from
this image.
A slightly more sophisticated approach is to produce two JPEGs. Place
the smaller one in-line on the page and make it a hyperlink to the
larger JPEG. This is what I used to do back in 1994, but it upset me right
from the start that there was no effective way to caption the image. I
also didn't like the fact that the user only got to choose from two
sizes unless I uglified my pages by adding a second hyperlink to a
"huge" JPEG.
At right: a thumbnail linked to a larger, static JPEG. Note that
there is no convenient way to associate a caption with either image and
certainly the user won't get any context once he has requested the
larger JPEG. Note: this is, of course, my little angel Alex at the age
of three months, from http://photo.net/photo/alex.html
In the "Road to Hell is Paved with Good Intentions" department,
technologists began to offer interactive systems. The server would
store a high-resolution image and deliver to users the resolution,
quality, and cropping that they requested, thus making optimum use of
scarce Internet bandwidth. The Hewlett-Packard OpenPix tools, available
from http://image.hp.com,
are the best-developed example of this idea. [Note: HP dropped support for FlashPix/OpenPix in 1999]
Try out the Java applet below
(from http://photo.net/photo/flashpix-reference-images.html).
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The user can pan, zoom, and get to any pixel of this 72 megabyte image without ever having to download the entire 72 MB file. Technology doesn't get better than this... or does it? Do your readers want a user's manual off to the side of every image? Or a toolbar at the bottom? Do they want to have to learn to use an applet just so they can surf your site? Does this way of exploring images not make the pleasant activity of Web browsing a little too much like the hard work of using Adobe PhotoShop?
Think about the user interface of the "small linked to large" system from the user's perspective. The publisher shows you a small picture. If you want a bigger view, you click on it. This is fundamentally the correct user interface, but it is a shame that clicking on an image doesn't also result in the display of a caption, of technical details behind the photograph, of options for yet larger sizes.
What readers really want is for a thumbnail to be a link to an HTML page showing the caption, technical details, a large JPEG, and links to still-larger JPEGs and interactive OpenPix sessions. This will involve a lot of work unless the publisher has automated production from PhotoCD through to the Web directories (more on that below), but the users get the best possible interface... or do they?
What can my server infer from the user's action in clicking on a
thumbnail? That he wants to see a 512x768 pixel JPEG? What if he has a
really big monitor? A really small monitor? A really slow Internet
connection? A really fast Internet connection? What if technology
evolves and things like OpenPix get rolled into all the browsers? What
if he has previously told me what he wants?
Most of the thumbnails on my site are now linked to computer programs. Since I run AOLserver, these are written in the AOLserver Tcl API but they could just as easily be Perl CGI scripts or ASP pages. The programs first check the Magic Cookie headers on requests for larger images. If the user has previously said "I'm a nerd with a 1600x1200 pixel monitor and a fast connection, please always give me 1000x1500 pixel JPEGs by default" then my program sees the cookie and generates an HTML page with a large JPEG on it, plus the caption and tech details (if available). If there is no cookie, the program has a reasonable default (in 1998, it is to serve an HTML page with a 512x768 pixel JPEG, captions, and links) plus a "click here to personalize this site" option. Try it out with the image at right.
Image base/16 base/4 base base*4 base*16 Resolution 128x192 256x384 512x768 1024x1536 2kx3k Amount 100 100 100 100 100 Radius 0.25 0.5 1.0 2.0 4.0 Threshold 2 2 2 2 2
Be prepared to undo and change the settings if the result isn't what you want. Unsharp Mask finds edges between areas of color and increases the contrast along the edge. The Amount setting controls the strength of the filter. I usually stick to numbers between 60 percent and 140 percent. Radius controls how many pixels in from the color edge are affected (so you need higher numbers for bigger images). Threshold controls how different the colors on opposing sides of an edge have to be before the filter goes to work. You need a higher threshold for noisy images or ones with subtle color shifts that you want left unsharpened.
One of the rationales behind this approach is that you never sharpen twice and that sharpening is always the very last image processing step. That's why an intermediate PhotoShop native format file is necessary.
Here's the format for the description file:
and an example from one of my own disks:line 1: spec for which resolutions to convert line 2: on which resolution images to write copyright notice | notice line 3: apply sharpening? (scanning blurs images) line 4: add black borders (nice for negatives) line 5: URL stub (where on the server will this image reside?) lines 6-N: one line/image, formatted as the example below <number on disk>|<target file name>|<which_resolutions>|<caption>|<tech details>|<alt>|<tutorial info>
The first line says "By default, for each image, convert the first, third, and fourth resolutions from the PhotoCD file." The second line says, "On the third, fourth, fifth, and sixth resolutions, add 'copyright 1993 philg@mit.edu' to the bottom right corner of the JPEG." The next few lines specify that all images from this disk will be sharpened and surrouded by black borders. The files will reside in the101100 001111|copyright 1993 philg@mit.edu sharpen:yes borders:yes url_stub:/photo/pcd1765/ 2|bearfight||Brooks Falls, Katmai National Park|Nikon 8008, 300/2.8 AF lens (used in MF mode), FOBA ballhead, tripod, Kodak Ektar 25 film 3|montreal-flower||In Montreal's Botanical Gardens|Nikon 8008, 60/2.8 macro lens, Fuji Velvia 4|montreal-olympic-stadium||Montreal's Olympic Stadium|Nikon 8008, 20/2.8?, Fuji Velvia
/photo/pcd1765/
directory from my server
root.
The first image that I say I want converted is actually number 2 on the disk
(at right). I want the JPEG files to contain the word "bearfight". The
next field is empty ("||") because I'm satisfied with conversions to the
default resolutions (1,3, and 4). The caption comes next and, finally,
some technical information behind the photo (most publishers wouldn't
care about this but remember that I publish photography tutorials in
addition to travelogues).
What do I get for all of this? Most valuably, http://www.photo.net/photo/pcd1765/index-fpx.html. Here's a fragment of the HTML from that undifferentiated list of all the photos on the disk:
Note that this linked thumbnail can be cut and pasted into a document anywhere else on my Web server because the IMG and HREF are both to absolute URLs (beginning with a forward slash). In fact, I don't cut and paste. I've programmed my text editor (Emacs) with a new command so that I can just type "1765" and then "2" and the editor finds the reference and inserts in into a document. Once I've written all the captions, it takes me only about an hour to add 100 images from a single PhotoCD to HTML documents dispersed around my server.<a href="http://www.photo.net/photo/pcd1765/bearfight-2.tcl"> <img HEIGHT=134 WIDTH=196 src="http://www.photo.net/photo/pcd1765/bearfight-2.1.jpg" ALT="Brooks Falls, Katmai National Park"> </a>
There are a couple of things to note about the .tcl script to which the thumbnail points. First, it runs inside the AOLserver process rather than as a separately forked CGI script. This is at least a factor of 10 more efficient than starting up a Perl script or whatever. Since the script executes only when a user clicks on a thumbnail, the efficiency probably doesn't matter unless you have an unusually popular site on an unusually wimpy server. Still, I like to conserve my computer's power for image processing and running Oracle.
The second point is about software engineering and is hard to illustrate without showing the source code for the Tcl script:
Yes, the whole thing is basically just a single procedure call toset the_whole_page \ [philg_img_target $conn \ "/photo/pcd1765/" \ "IMG0002.fpx" \ "bearfight-2" \ "784" "536" \ "copyright 1993 philg@mit.edu" \ "Brooks Falls, Katmai National Park" \ "Nikon 8008, 300/2.8 AF lens (used in MF mode), FOBA ballhead, tripod, Kodak Ektar 25 film" \ "" ] ns_return $conn 200 text/html $the_whole_page
philg_img_target
, defined server-wide. Suppose Web
standards evolve so that there is a way for the server to tell a client
to what color space standards an image was calibrated.
By changing this single procedure, I can make sure that all of the
thousands of images on my site are sent out with a
"I was scanned in the Kodak PhotoCD color space" tag. My photos will
then be rendered on users' monitors with the correct tones (right now
they come out way too dark on most Windows and Unix machines, and a bit too
light on the average Macintosh).
All of the personalization code that sets and reads magic
cookies is also encapsulated in philg_img_target
(the
source code for which is available at http://photo.net/wtr/thebook/philg_img_target.txt).
How does this all happen? The image conversions from PhotoCD to JPEG are done with ImageMagick. You can find precompiled binaries for most Unix variants and also Windows 95/NT at http://www.imagemagick.org. Here's what a typical ImageMagick command (to make a thumbnail JPEG) looks like:
Note that this is all a single shell command. I've used a bunch of optional image processing flags before the "from-file name." Because I don't like progressive JPEGs (see below), the default from ImageMagick, I invoke "-interlace NONE". Any kind of scanning introduces some fuzziness into the image so I ask ImageMagick to sharpen a bit with "-sharpen 50". I want a two-pixel border all around, so I use "border 2x2". I could choose the color but the default will be black. Finally, ImageMagick lets me add a comment to the JPEG file. Anyone who opens the JPEG with a standard text editor like Emacs will be able to see that it is "copyright Philip Greenspun" (conceivably other programs might display this information, but PhotoShop doesn't seem to, on either the Macintosh or Windows). See http://photo.net/wtr/thebook/imagemagick.html for a complete list of options.convert -interlace NONE -sharpen 50 -border 2x2 \ -comment 'copyright Philip Greenspun' \ '/cdrom/PHOTO_CD/IMAGES/IMG0013.PCD;1[1]' bear-salmon-13.1.jpg
The from-file name, "/cdrom/PHOTO_CD/IMAGES/IMG0013.PCD;1[1]" is mostly dictated by the directory structure on a PhotoCD. However, the final "[1]" tells ImageMagick to grab the 128x192 pixel thumbnail out of the Image Pac ("Base/16" size in Kodak parlance). The to-file name, "bear-salmon-13.1.jpg" includes the image number (13) from the original PhotoCD to make it easier for a human to find the entire Image Pac if requested.
ImageMagick is convenient but typing 300 commands like the above for each PhotoCD would get tedious. You know that an MIT woman really loves you when she offers to spare you the horrors of writing Perl. Just grab http://photo.net/wtr/thebook/pcd-to-jpg-and-fpx.txt if you want to use the Perl script that my girlfriend wrote as an expression of her love for me. Of course, no romance is one sunny Perl-filled day after another. When she delivered the code, I complained about the lack of data abstraction and told her that she needed to reread Structure and Interpretation of Computer Programs (Abelson and Sussman; MIT Press 1997), the textbook for freshman computer science at MIT. I also asked her to rename helper procedures that returned Boolean values with "_p" ("predicate") suffixes. She replied "People will laugh at you for being an old Lisp programmer clinging pathetically to the 1960s" and then dumped me.
With a minimum of mechanical labor, I managed to get thousands of images on-line, in three sizes of JPEG and a 2000x3000 pixel FlashPix. What was my reward? Hundreds of e-mail messages from people asking where they could find a picture of a Golden Retriever or a waterfall. Once again MIT friends and Perl came through for me. Jin Choi spent 15 minutes writing a Perl script to grab up all my captions from the flat files into one big list. I then stuffed the list into an Illustra relational database table:
After an hour or two of programming, I was able to let users do full-text searches through my image filenames, captions, and tech details from http://db.photo.net/stock/. Try it out right now withcreate table philg_photo_cds ( photocd_id varchar(20) not null primary key, -- bit vectors done with ASCII 0 and 1; probably convert this to -- Oracle 8 abstract data type jpeg_resolutions char(6), -- on which resolutions to write copyright label copyright_resolutions char(6), copyright_label varchar(100), add_borders_p char(1) check (add_borders_p in ('t','f')), sharpen_p char(1) check (sharpen_p in ('t','f')), -- how this will be published url_stub varchar(100) -- e.g., 'pcd3735/' ); create table philg_photos ( photo_id integer not null primary key, photocd_id varchar(20) not null references philg_photo_cds, cd_image_number integer, -- will be null unless photocd_id is set filename_stub varchar(100), -- we may append frame number or cd image number caption varchar(4000), tech_details varchar(4000) ) -- build a full-text index using the PLS extension to Illustra create index philg_photos_pls_index on philg_photos using pls ( filename_stub, caption, tech_details );
Is this a great system or what? Let's consider what happens if I make a
mistake in spelling a word in a filename. To correct the mistake, I
have to change the description.text
file. Then I must
either rerun the conversion script over the entire PhotoCD or manually
change the filenames of three JPEGs (plus all the HTML documents that
reference the thumbnail). I have to rename the .tcl script that
corresponds to the image and also update a row in the relational
database table that sits behind the stock photo index system.
Perhaps it would be better to keep the image information in just one place: the relational database (RDBMS). Then we can drive the image conversion and .tcl file production from there. If we were willing to make the serving of plain old images dependent on the RDBMS being up and running, then we could just have HTML files reference photos according to their ID in the database and dispense with the static .tcl files.
Once we're running this as a database service, wouldn't it make more sense to let other people use it? If many photographers are using the same RDBMS server, then a fifth grader doing a report on Paris could search for "Eiffel Tower" and find all the photographers who had images of that monument and were willing to share it. It could also be useful for professional photographers who wanted to collaborate around images with their clients.
Coincidentally, that's been one of my back-burner projects for about three years. I think I might have it done by July 1999, though. Check http://photo.net/photo/.
A few months after my site went up, magazines starting asking for high resolution digital files corresponding to, say, http://photo.net/samantha/bear-fight.jpg I wanted to send them the original .pcd file from the PhotoCD, but the URL told me nothing about which of my dozens of PhotoCDs held the Image Pac. When I'd use an image from Travels with Samantha in another service, such as photo.net, I'd have to use a cross reference.
After a couple years of this, I hit upon the following system:
<IMG SRC="/photo/pcd1253/pink-lady-and-dogs-8.1.jpg">
<IMG SRC="/photo/pcd1253/pink-lady-and-dogs-8-sm.jpg" WIDTH=192 HEIGHT=128>
Note that if the image isn't exactly 128x192, the browser will crudely resize it to fit, potentially resulting in a fuzzy or blocky picture. Publishers who don't use automated production techniques such as those described above oftentimes find that they are lacking the desired size of digital image. They think to themselves, "I know that I want it to be 200x300 pixels so I'll just put in WIDTH=300 HEIGHT=200 tags". Here's the result, an e-mail message from a friend and my response:
Unless you're using my batch-conversion script or Web/db application, it is probably best to leave the WIDTH and HEIGHT blank. When you're all done with the page, run WWWis (originally "wwwimagesize"), a Perl program that grinds over an .html file, grabs all of the GIF and JPEG files to see how big they are, then writes out a new copy of the .html file with WIDTH and HEIGHT attributes for each IMG. The program is free and available from http://www.tardis.ed.ac.uk/~ark/wwwis/.I have just been through [a part of his site], which was completed six months ago. It is beginning to erode. The images are fading. Something is wrong with the server, or somewhere down the pipe. I am very worried that everything I'm doing has the possibility of fading. The images look weakened, diluted, and on the Mac, they look shamefully weak, like there's some complete idiot behind the site. None of us are idiots, and I may have been very inexperienced at the beginning of this web site, but I've been working with digital images since 1990 and I've never known of this happening before. Something has to be done soon about this. I notice in that you're using WIDTH and HEIGHT tags in Netscape to rescale your images, e.g., on http://.. [*** URL omitted to preserve my friendship ***] do a "Page Info" in Netscape and you'll see that it is "455x288 (scaled from 504x319)".
Other attributes potentially worth adding to your HTML tags are the following:
I personally don't like interlaced GIFs or progressive JPEGs (which only work with Netscape 2.0 and higher). The theory behind these formats is that the user can at least look at a fuzzy full-size proxy for the image while all the bits are loading. In practice, the user is forced to look at a fuzzy full-size proxy for the image while all the bits are loading. Is it done? Well, it looks kind of fuzzy. Oh wait, the top of the image seems to be getting a little more detail. Maybe it is done now. It is still kind of fuzzy, though. Maybe Greenspun wasn't using a tripod. Oh wait, it seems to be clearing up now ...
A standard GIF or JPEG is generally swept into its frame as the bits load. The user can ignore the whole image until it has loaded in its final form, then take a good close look. He never has to wonder whether more bits are yet to come.
The most serious problem with JPEG files is that they aren't stored in any kind of standard color space. So if you edit them to look good on a Macintosh monitor (gamma-corrected), they might look horrible on someone's PC or Unix machine (typically not gamma-corrected). PhotoCD Image Pacs are always produced in a calibrated color space, thus preserving your investment in an image library against the day when the Web standards finally enable a publisher to specify a gamma along with an image. It is also possible to obtain FlashPix-format scans in a calibrated color space.
Note: One of my favorite photo labs, Portland Photographics, deals with gamma in a very interesting way at http://www.portphoto.com/. I've written a bit more myself on the subject at http://photo.net/photo/fixing-gamma.html.
If you're in a hurry to get a handful of images from slides or negatives onto the Web, you may wish to use a desktop film scanner. The most interesting recent practical innovations in desktop scanners are systems that look at a piece of film from different angles and try to figure out what is a dust particle or scratch and what is part of the camera-formed image. An example of this technology is "Digital ICE", incorporated in the Nikon Super Coolscan 2000.
Current digital cameras are a mess both in terms of quality and ergonomics. Consumer products engineers tend not to innovate and the imaging pipelines of products you can buy in 1998 are therefore largely derived from video cameras, where resolution of more than 640x480 pixels isn't useful. The goal for most companies is a high-quality camera with 1000x1000 pixel resolution. One million pixels is the number at which most people will accept a small print as "photographic quality." Note that there are many factors affecting image quality other than resolution. In some ways, a digital camera could produce better quality than a film-based camera because you can have purer whites under artificial lighting, greater dynamic range, and higher sensitivity (so you aren't forced to use on-camera flash).
If you need to get to the Web quickly and don't ever expect to want a wall-sized enlargement, you can probably find a good digital camera in September 1998 for $600. However, in the long run you might not want a still camera at all. The Canon XL-1 DV camcorder makes 30 digital still images per second that are about as good as you get from cheaper digital "cameras." So you can wait until after you get home to decide whether to present video or still pictures (see http://photo.net/wtr/streaming-video.html for accounts of my struggles in transferring digital video to hard disk; the short answer: Buy a Miro-brand board; don't buy a DPS-brand board).
Let me indulge in some punditry here. When digital cameras become widespread, people are going to need much more disk storage. That's because there is virtually no operating system support for migrating little-used data out to tape, even if the average person had a tape drive. The best Japanese digital still cameras will be made by Sony and Canon because they have such great experience in engineering video cameras. The best consumer-priced cameras overall, though, will come from Hewlett-Packard. Why? HP has better engineers to sweat the analog and digital signal processing details of the imaging pipeline and they have much more taste in user interface than the Japanese companies.
Once digital cameras become ubiquitous, you should figure out ways for users to contribute images to your site. Anywhere that users contribute text is an opportunity for you to let them contribute pictures as well.
Here are two common uses of watermarking:
But realistically litigation in the United States isn't for middle class people. I couldn't afford to hire a team of lawyers to chase down the miscreants and I didn't want to spend my life filing lawsuits myself. I decided to focus my energy on creating new works and not lose sleep over piracy of the old ones.
Then one of my readers e-mailed me a Web page with an uncredited usage of one of my bear photographs from Travels with Samantha: ". . . Yes, the IRS does try to intimidate and bully you. And, they publicly crucify some public figure each year (Willie Nelson, Leona Helmsley, Darryl Strawberry, Pete Rose, etc.) who has been caught with allegedly "fudged" returns. But, as you will learn, there is NO LAW, anywhere, that mandates you file a tax return! . . ." For $88-1000, you could purchase assistance in "How To STOP Paying Federal Income Tax - LEGALLY!"
This wasn't exactly what I had in mind when I set up my site, so I sent the company some email requesting that they remove the picture. The response was frustrating but I was open-mouthed in admiration of its creativity:
Our programmer says that he has never seen your book, and that the picture came from a site that listed lots of pix (both gif & jpg) which were presented as available for download by anyone! At this point we are not interested in getting into a tussle with you, but the question is now open whether the picture is original with you or you took the picture from the same source. We'll need some coroberation to verify your claim to the picture before we go any farther. Dana Ewell, CEO !SOLUTIONS! Group
I still didn't have enough money to hire a team of lawyers to "put the genie back in the bottle" but I thought I could use my assets: (1) my site is more interesting than average; (2) my site is more stable and, because it is so old, better-indexed than average. Every time another publisher used one of my 4000 on-line images with a hyperlinked credit, I might earn a new reader. Did their site suck? So much the better. The user wouldn't be likely to press the Back button once he or she arrived at my site through the "photo courtesy Philip Greenspun" link. Of course, my site is non-commercial so extra readers don't bring me any cash, but I do like the idea that my work is broadly exposed to people who might not find it otherwise. That took care of the good-faith users. Could I use my site's stability and presence in Web indices to deal with the bad-faith users?
It hit me all at once. An on-line Hall of Shame. I'd send non-crediting users a single e-mail message. If they didn't mend their ways, I'd put their names in my Hall of Shame for their grandchildren to find. I figure that anyone reduced to stealing pictures is probably not creative enough to build a high Net Profile. So a search for their name won't result in too many documents, one of which will surely be my Hall of Shame. What if the infringer were to retaliate by putting up a page saying "Philip Greenspun beats his Samoyed"? Nobody would ever find it because an AltaVista search for "Philip Greenspun" returns too many documents. Try it right now, then try "Shawn Bonnough" for comparison, making sure to include the string quotes in both queries.
A practical-minded person might argue that my system doesn't get me any cash or stop any infringement. A technology futurist might argue that one of the micropayment schemes from the 1960s is going to be set up Real Soon Now. Both of these people are right I guess, but I won't be sorry if what seems to be the evolving custom on the Internet solidifies into law: send e-mail asking for permission to republish, be scrupulous about crediting authors, and prepare to be vilified if you flout these rules.
Would that be the best possible system? Maybe not, but it has to be much more efficient for society than a bunch of corporations hiring lawyers to sling mud at each other in court. Under my system, we can enjoy seeing our work (with credit) on other folks' sites, vent our spleens at midnight by adding to a Web page of transgressors, and then move on to new productive activities.
I wonder what your thoughts are on digital watermarks as a way of retaining copyright. I had a similar theft-of-image-from-web experience, which is detailed at http://www.arborlaw.com/ war.htm. Am still contemplating best way to prevent further outrages.Also; re comments on best consumer digital cameras: don't count out Kodak. I have been very pleased with their DC210; excellent color, easy to use, software is acceptable.
Recommend a link to http://www.dcresource.com/, the Digital Camera Resource Page - good overview of models available and a good reader's comments section.
-- Mike Gould, April 30, 1998
This is exactly the kind of nuts-and-bolts type of explanation that is needed in this book. I think that most web publishers will consider photos on the site as a secondary focus, rather than primary as in the case of photo.net. Therefore, the big issue of having a 72dpi dull and lifeless JPEG is not such a huge concern. Having said that, however, good photos can really spice up a page. Just think of this page without any pictures! All text, dull and drab. We have Philip's photos to break up the monotony of the page, and if one catches our eye, we can click on it to see a larger view and all the important details like which camera he used, maybe sparking off that N vs. C discussion.Regarding copyright, one important point: if the image is valuable to you, and you can't stand the thought of someone stealing it, don't put it on the web. It is that simple. Consider this: at the moment that the person views your page, you have essentially "given" the image and its contents to the viewer. It resides in the cache of the browser. These days, all it takes is a mouse click to copy the image and steal it. Yes, it is unethical and wrong. But how do you prosecute somone? What if that person is in another country, where copyright laws are nonexistent? What recourse do you have?
There are ways to "protect" your images. You can use Photoshop to put a big, ugly copyright notice right smack in the middle. But...I haven't seen that deter many people from publishing photos with a prominent copyright in blatant violation on their own personal home pages, especially "fan" pages.
Moral of the story: If is is too valuable to lose or have stolen, don't put it up on the web. These days, the number of people who are dishonest and will steal images, text, etc. far outnumber the few who ask permission, give credit, and do the right thing. Let's hope that it changes soon. But I am not holding my breath...maybe the Hall of Shame could be expanded for other photographer and web publishers to nominate the people and sites that violate copyrights.
-- Matthew Endo, July 21, 1998
Kodak PhotoCD is also being used by cultural institutions like libraries, archives and museuems. They're concerned about the long-term viability of the PCD format (something Phil discusses) and broader issues like image quality for providing usable substitutes. Now there's a study by the Conservation and Preservation Department at Cornell University on the Photo CD at http://www.library.cornell.edu/pr eservation/kodak/cover.htm Not too well publicized but quite interesting, even for people outside the archives-library circuit.
-- Paul Romaine, August 9, 1998
I was somewhat puzzled over the reasons suggesting ordinary jpegs over progressive jpegs. There are two main points described in the chapter; 1. the user will be confused and unable to tell whether the image is finished loading. 2. the user will be forced to view a blurry version as it loads.I think the user will understand the loading concept just fine. We have that little top-right icon telling us something is loading, and we have the statusbar at the bottom, saying "loading 30kb of 150kb (20% done, 40 seconds remaining)" or something like that. Maybe the user will be a bit confused the first time he/she encounters a progressive jpeg, but in the long term? I doubt it.
2. Being forced to watch a blurry low-res version as it loads, is that really a bad thing? I think not, it gives you a much idea of whether it's worth the wait, than what normal jpeg will provide (if you clicked through a thumbnail, this might not apply). I find it much more interesting watching a progressive jpeg evolve, I can actually get a better idea of the picture with it's boundaries set. I find a normal jpeg a real test of patience, as it's pretty distracting to really focus on something which ends are undefined. It's useless until it's done, a progressive is not.. Or something like that.
The one thing that would tip the scale in favor of ordinary jpegs for me, would be the support of the format. I know newer Netscape supports it, while other browsers simply displays them as ordinary jpegs. Or do they? Is it really 100% safe to use progressive jpegs? Or will some browsers refuse to display them, claiming it's an unknown format? I think the information about this could be have a bit better in the chapter.
Other than that, I really enjoyed this chapter and as usual when reading on this server, I learned a lot.
ps! A bigger box to type in would be very nice - (I gave up, and eventually pasted this from an editor.) And a spell checker.. :-)
Best regards Christian Figenschou
-- Christian Figenschou, October 25, 1998
Interesting - go to altavista, search for Philip Greenspun, and it returns as a recommended link: Body painting. Anything you want to tell us, Philip? ;)
-- Brian St. John, March 11, 1999
Faced with a disk full of PhotoCD images and a huge dislike for mechanical munging, I decided to battle Win95 and get the code running there (note that I only did the image preparation - nothing on the server side). Here's the basic steps that got it running for me (in Sep98):Get the Convert program 1) Download the Win95 convert program utilities from http://www.wizards.dupont.com/cristy/ImageMagick.h tml and install as described by their docs (basically unzip and run). You only need the file ImageMagick-nt.zip not ImageMagick-4.0.9.zip (unless you want the source code).
2) This is sufficient to (mostly) run convert (and the associated utils). Great for one off files, but not sufficient for munging an entire CD. I couldn't get some of the X terminal options like -bordorcolor to work quite as I expected, but this seemed to disappear later (after the steps below).Get Perl
1) Track down perl for Win95/NT from http://www.perl.com/. It leads to pointers to two versions and a discussion of them. I used api502e.exe from somewhere on http://www.activestate.com/.
2) Install it. Allow it to modify the autoexec.bat etc. 3) Retrieve the script from http://photo.net/wtr/thebook/pcd-to-jpg-and- fpx.txt and save it with a .pl extension. Modify it as follows: 3a) Tweak the convert.exe path and PhotoCD location path. E.g.: #FILE LOCATIONS $exec_cmd = 'c:\\tools\\im\\convert.exe'; #the exec name for ImageMagick #Image Pac location; only the lowercase portion varies # $pcd_image_directory = '/cdrom/PHOTO_CD/IMAGES/'; $pcd_image_directory = 'd:/pcd2015/'; 3b) Munge single & double-quotes so the MS-DOS command line doesn't choke From: $comment_cmd = " -comment \'$copyright_text\'";
To: $comment_cmd = " -comment \"$copyright_text\"";
From: " -draw \'text $draw_width, $draw_height \"$copyright_text\"'";
To: " -draw \"text $draw_width, $draw_height \'$copyright_text\'\"";
From: $pcd_name = " '$image_file\[$i]'";
To: $pcd_name = " \"$image_file\[$i]\"";
It might not look quite right, but it is (due to weirdo embedded quote behaviour).
4) This is sufficient to get the Perl script running and images converted en masse - except that the caption is not written in the border because there is no Postscript support. E.g. something like: perl ..\pcd-to-jpg-and-fpx.pl pcd2015.txt will produce renamed jpgs, html files etc as described in pcd2015.txt.Get Ghostscript so that Postscript conversion works.
1) A recent Ghostscript can be found at http://www.cs.wisc.edu/~ghost/aladdin/get510.html which has a link describing the Win95 install at http://www.math.utah.edu/~beebe/ghostscript-on- windows.html. Note that the optional step of installing extra fonts should be in c: \gstools\gs5.10\fonts rather than c: \gstools\fonts as it implies. Check that it doesn't get buried as ...\gs5.10\fonts\fonts (though I have no idea whether this extra font info is even necessary).
2) Put c:\gstools\gs5.10 into your path (though this also may not be strictly necessary)
3) Define a new environment variable: SET GS_LIB=c:\gstools\gs5.10;c:\gstools\gs5.10 \fonts (both directories are necessary)Re-run the perl command and load up index- table.html to view the results of your handywork.
That's it! Easy huh :-)
-- Michael Mee, March 18, 1999
I was disappointed that there was no free (open source) solution for those who wanted to host FlashPix images on thier servers. So disappointed that I began a project to develop such a solution. See http://www.milo.org/milo.iip.html for more information.
-- Craig Pennington, April 6, 1999
Kodak has jumped onto the bandwagon. They have a free server software package that you can use to serve up images. The concept is that you place your PCD images directly on the server, and the program will convert to JPEG on the fly. They have added FlashPix-like zooming and panning for Java-enabled browsers--no more platform-specific plugins. See http://www.kodak.com/global/en/professional/support/PCDWeb/welcome.shtml for more. (This link may change in the future as things tend to move around on the Kodak web site)
-- David Elfstrom, April 24, 1999
Hi Phil,After reading through all of your well thought out and informative content, I could only wonder why you did not mention actual copyright ownership, as in ... contacting the Library of Congress, filing your form, paying your $20 and "owning" the rights to your photos. As an artist, I find this very beneficial. A situation such as you had, requesting that you "prove" it was yours, would be a much simpler matter to resolve I would think. Also, another way I have found to hamper the lowly from "stealing" my work, is to add a rather large )HALPERIN over the image, while still retaining the original free of this rather homely signature. If a person wants to spend the countless hours in Photoshop or similiar, attempting to remove this, they probably deserve to use it for a little while :~
Ciao 4 Now,
Zoe
-- Zoe Halperin, April 29, 1999
Philip doesnt discuss a way to remove "Photo CD haze" through ImageMagick. I recently got a bunch of negatives scanned, and all of them came back with a haze (the slides didnt have this). I found the Enhance|Normalize in the ImageMagick Display program (there ought to be a command from the Convet program) did this job quite well. May or may not work for others, but worth an attempt.
-- Shayok Mukhopadhyay, May 13, 1999
One thing you mention is how there is no convenient way to caption images. In fact, there is a relatively simple way to have images captioned with HTML. Rather than adding the align=left or align=right attribute to an image, put the image in a table, along with the caption text, and add the align=left/right attribute to the table.If you then add a background colour to the table and/or change the font size, the results can be quite effective.
-- Luke Andrews, May 27, 1999
Hey, great page. I kind of come from the other side of the world from a lot of professional photographers--my forte is in computers, but I fare fair as a photographer as well. Viva la K1000. :-)
Anyhow, if you're interested in adding captions to your pictures, one of the current quick-and-dirty ways is to add ALT text like the picture to the right. Both Microsoft Internet Explorer 4 and Netscape Navigator 4 (on PC's at least; I can't remember on the Macintosh) will display a "Tool Tip" of the ALT text when you mouse-over-and-wait. (FYI, the HTML for the image to the right is <IMG SRC="http://www.servtech.com/~jayce/images/KidsDrivingT.jpeg" ALT="Kids Driving, 1992 Saturn Owner's Manual" ALIGN="RIGHT" HEIGHT="113" WIDTH="168"> and I put it before the paragraph with a <BR CLEAR=ALL> statement to ensure the image lined up correctly. Let's just hope I didn't mistype anything.)
Another technique is, of course, to make a separate web page for the big images which contains some additional info about the picture. I'd imagine it'd be incredibly unruly for 4,000 images.
For the other visitors to this page, I'd like to mention that the size (HEIGHT= and WIDTH= fields) are especially useful to Internet Explorer 4 because it will render a page before the images load--a boon to slow-connected individuals such as myself. By adding the size information, the frames for the pictures are the correct size and the text doesn't re-flow every time an image loads.
-- Jason Olshefsky, May 27, 1999
Great info. A couple of thoughts.I run a web site with helicopter photos called Helispot (http://www.helispot.com). Much of the info you provided is stuff that I currently use daily.
First off, PhotoCD's do look great. Everybody always writes and asks why the photos that I took have such great clarity. I owe it to good pro slide film, PhotoCD scanning, and Photoshop!!! I'd also add, I find that I need to add about 10-20 ticks on the BRIGHTNESS control to make images look ok on my web site. If I post them without brightening them, they come out dark. I also agree with you when you said to slide the black level slider to the right a little bit in the LEVELS menu.
As for progessive JPEG's, there is a problem for sure. I started using them for a short time, then I realized that Netscape Communicator (currently version 4.x) will display them, but Internet Explorer (versino 4.x) will not. So, viewers of my site must wait for an entire JPEG image to load before it is viewable. AOL uses Explorer for its viewer as well. Not good.
Also, a note about JPEG's and distortion. Try this test and you'll learn so much. Open an uncompressed image in Photoshop, such as a PhotoCD image, or a TIFF file, and use the "Save As" function in Photoshop to save it as a JPEG file. Photoshop will ask what level of reduction you want (1 through 10), so select 1 (most compression, ugliest results), and save it. Then, look at the size in your file folder and make a note of it. Then, while leaving Photoshop running, view the file in a different viewer (I'm a huge fan of Vueprint Pro for the PC), or you can even load it directly into your browser using the "Open File" command. Notice all the edge distortion and solid color posterization!! OK, now, go back into Photoshop, and click on "Save As" again. The filename that you saved it as originally will automatically fill back in. Use that filename again, but when it asks for the reduction amount, select a higher level, maybe 3 or 4. Go back to your viewer and re-load the image. Notice how it clears up a little bit. Do this over and over again, all the while checking how the file gets bigger and bigger in the directory as you save it with higher quality settings (lower file size reduction). Some files, such as photos I've taken of helicopters hovering against solid blue skies, require the highest quality when saved (lowest compression), otherwise the sky turns "blocky". Others, with tropical foliage backgrounds, can be reduced quite a bit. But it's fun to see the difference. Note, Photoshop will save the file compressed but leaves the one in memory uncompressed, so when you save the file as a JPEG, it won't show any distortion in Photoshop unless you close the file down (clear it from memory), then re-open the JPEG from disk. But by then, you've lost the original unless you have it on disk. Important to know, for those of you, like me, who have to scan some stuff from prints and don't want to have to re-scan something a second time!!! Slow!!!
Great article. Really good info.
-- Alex Calder, June 29, 1999
Phil says: "About $1 to $3 for a standard scan from a 35mm original... (...it is cheaper to have a PhotoCD made than to buy a hard disk capable of storing that much data)." This is no longer true - a high-end 9G SCSI drive (IBM Ultrastar, Ultra Wide 7200RPM) costs less than $300, which means space for 15 CD images for less than $20 each.
-- Dmitry Kohmanyuk, July 6, 1999
I think the example you work through for using Photoshop is very interesting, because I'm not sure that I like the result that much (I'm talking about the images as they appear in the printed version, online they look much different). First of all, my initial first impression was to prefer the more "purple" image over the more garish processed version. Looking at it some more, I couldn't shake the feeling that there was something else that was funny about it... it *looks* digitally processed somehow. Something about it screams "this image has screwed with on a computer".I understand that you were just trying to get it to look more like what you saw through the camera, and I do understand that any photographer would look at the first image and think "Huh, too much magenta", but maybe photoshoping things up the wazoo isn't quite the solution.
-- Joseph Brenner, July 13, 1999
I'm not sure whether to post this here, or under the article on slide scanners, but I'd like to share my experience with getting my first batch of 35mm slides scanned to Kodak PhotoCD. I live in Sydney, Australia so your mileage might well vary. There are very few firms offering PhotoCD scanning here. As far as I know, there's only one here in Sydney, so there's not much competition. Pricing (in Australian dollars) works out like this for a standard (non-Pro) CD:$10 for the CD plus $4 per slide plus 22% sales tax. So a Photo CD filled to capacity with 100 image packs would cost something like $500 dollars. A Nikon Coolscan 2000 sells for around $2000 here, so four or five CDs would pay for the scanner. Even so, I'm not too keen on cluttering up my study with yet another box, and I like the idea of a standard, calibrated product to manage and archive my slides.
However I recently had a discussion with the people who produced my PhotoCD about some quality issues. Most of the images looked good, but some had the highlights burned out and others had colour casts. I triple-checked the CD images against the original slides, and the problem was not there. When I raised this, the vendor explained that this was what they'd expect from the "budget scan". Apparently they leave the scanner on automatic, and if (for example) the slide has large areas of dark tones and a small area of sky, the scanner assumes it's underexposed and unilaterally lightens the whole image, burning out the cloud details. Similarly, Im told that the colour casts occur when theres a large area of one intense colour, and the scanner assumes its a colour cast in the slide and attempts to compensate. I was told that if I wanted anything better, I need to specify the Pro scan. Unfortunately, that costs twice as much, and of course one gets fewer image packs per CD which boosts the cost even further.
Is the vendor feeding me a line here, or is standard PhotoCD supposed to have these limitations? It's a bit frustrating to carefully juggle exposure between the shadow and highlight areas, get detail in both on the slide, and then lose it in the scan. I might just as well shoot print film and give it to my local mini-lab!
-- Robert Bryett, August 9, 1999
Macintosh users and PhotoCD: GraphicConverter (shareware!) will let you remove the "PhotoCD" haze and convert a batch of .pcd files into .jpg (or anything else, for that matter) files. Here's how to do it :PhotoCD haze :
Converting a batch of files :
- select Picture:Levels
- Click on the "Both" button and/or set the output levels yourself.
Disclaimer : I have no interests in Lemke software.
- In Edit:preferences, set which resolution of the .pcd you want to use in the open, PCD tabs.
- Select File:Convert More...
- click on Batch to add some processing during the conversion, such as adding a comment or sharpening the image.
- Select your files and click convert.
-- Patrick Dumais, August 24, 1999
I ran across a couple of other alternatives for captioning photos on web sites. Both use javascript, but work fairly well in most browsers.
http://helpmaster.com/htmlhelp/javascript/popjbpopup.htm
http://www.bosrup.com/web/overlib/
-- O.M. Jenkins, September 10, 1999
Your figures for monitor contrast range are possibly a bit optimistic. I have done tests of users ability to discriminate between grey levels on workstation monitors. Most users could disciminate less than 90 different levels of gray across a straight edge. The tests were done about seven years ago, so possibly monitors have improved since then.
-- Brian McBride, October 19, 1999
If I were to engage in some dastardly activity I don't think the Hall of Shame approach would work very well. Try doing the AltaVista search on David Stern. I got over 7,000 hits.
-- Dave Stern, December 31, 1999
My personal solution to the "thumbnail link to a page with a larger image" problem has been to create XML files, one per image, of the following format:
<?xml version="1.0"?> <photo> <title> My Cat Making a Face </title> <description> On one of the rare occasions where my cat, Van, was allowed outside, he kept making this great face--I guess he was trying to absorb every single smell/taste he could. *Shrug* </description> <image encoding="base64" format="jpeg"> <![CDATA[ /9j/4AAQSkZJRgABAQAAAQABAAD//gBrU0FORSBkYXRhIGZvbGxvd3MKCkNSRUFUT1I ... (this is the large .jpg file run through base64 encoding) CDj/v1taF/yFLX6N/KpekbCtZnSwWVx9nj3WrBtgyNvfFFXl+6PpRWHsfMrmZ//2Q== ]]> </image> </photo>Then I whipped up some CGI scripts using Perl's "XML::Parser" module to extract the image, run it through whatever "on-the-fly" image processing it needed, and send the resulting thumbnail / web page / whatever to the client's browser. If my large image is 1800x1200 pixels (as is the default from my Fuji MX-2700 digital camera) I can then offer a 180x120 thumbnail, a larger 450x300 (~4"x6") "print", and the very detailed 1800x1200 original, in case a user wants to see every pixel captured by the camera.
All told, I'm very happy with the results; it does require more CPU processing than static HTML pages to scale the images on the fly, but it saves disk space (no need to save 5 copies of the same shot) and it also saves on download time (it sends ONLY the information the user asks for) which is important since my ahem, "server" lives at the slow end of a 56k modem :-)
-- Dabe Murphy, January 6, 2000
I haven't used PhotoCD, but my experience with a film scanner is that unsharp mask works better with threshold > 2 for larger image sizes. Rather than keeping this value constant, I would recommend increasing it with resolution: 2 5 10 15 20. The primary benefit is that blue sky grain doesn't get any grainier with higher threshold values.
-- Bill Tuthill, April 4, 2000
I have been using Polaroid SprintScan 4000 since Feb. and really love it. To get a best scan, it takes around 2 minutes to scan a film at 4000 DPI on my 400 MHz Win 98 machine which has 512 MB RAM and 30 GB hard drive. It takes much less time if I just want to get a scan to share with friends and relatives over e-mail. I will tell you that it is hard to find such satisfication of viewing your own pictures on a 21 inch monitor. It is like viewing a big 8x11 original slide on a wall mounted light table without using any loupe.
-- nikonf5 lover, May 1, 2000
Philip's PCD conversion script is a very useful tool. However, I have been doing some work with digital cameras recently and really missed the convenience of being able to make a thumbnailed index with several other linked image sizes. Thus I wrote a script to do all of this for a directory of JPEGs. It will take a directory of JPEGs from any digital camera and produce a thumbnailed index page with links to a medium sized image page which, in turn, contains a link to a very large image. It does some sharpening and adds a border as well. It can be found here.
-- Joe Perrigoue, May 9, 2000
Previously I posted my own version of the perl script for converting PCD's to JPEG's and Flashpix, featuring new options for relative url's as well as creating the directories specified in the description file automatically. I corrected a small bug in my code which prevented relative url's being handled properly when the URL stub consists of two directories.I've also added the ability to specify the sharpness factor from 1-99 in the description file which will be used when the script is run.
The updated version is available here...
-- Geoff Armstrong, May 9, 2000
The best way to prevent rescaling from munging your images is to add either HEIGHT=100% or WIDTH=100% to your <IMG SRC> tag. Choose the longer dimension to display at 100%, and the image won't have to be scrolled. The really neat part is that the browser takes the viewer's screen resolution into account, so your picture fills (one axis of) the screen no matter what.
-- Tom Pappas, May 30, 2000
Well, I can't claim to be a accomplished HTML writer,but you can view my decent efforts at my home page. Also you can use a WYSIWIG editor like Frontpage just to fill up the images, as it will automatically generate the image sizes, and similar tags for easy page loading(you can always edit it in Notepad!).Shiva
-- Shiva Guru, November 28, 2000
I followed Philip's suggestions when I built my own photo website. Trust me, if I can do it, you can too. Give it a visit:www.jimtardio.com
-- Jim Tardio, January 18, 2001
Photo CD is no more
Alas, the Kodak Photo CD service has been discontinued, at least in the United Kingdom:
From hclark@kodak.com Tue Feb 6 05:05:22 2001 From: hclark@kodak.com Date: Tue, 6 Feb 2001 12:05:34 +0000 Subject: Photo CD From: Howard G Clark Thank you for your e-mail. We are sorry to state that we discontinued our Photo CD service in Dec 2000. [...] Best wishes for your photographyWe will have to develop more alternatives than just the drum scan option that Philip offers in this chapter.
-- Allan Engelhardt, February 7, 2001
The Digital ICE technology actually works by scanning in the infrared channel in addition to the R, G, and B channels. Since the infrared passes unobstructed through the film, only dust or other particles show up in that channel, and you can use the resulting image as a correction mask.
-- Zach Beane, March 1, 2001
Now that PhotoCD is almosty universaly substituted by desktop scanners, I want to pass a word of caution. These devices are susceptible to dust accumulating on internal optics and can gradually degrade image quality: here are scan examples and my recommendations on keeping scanners clean.
-- Vadim Makarov, June 4, 2001
For the information of those interested in computer programming: Philip's reference (above) to a great book called Structure and Interpreation of Computer Programs took me directly to amazon.com. In there, I read in one user review that the contents of this book were available at MIT's CS 6.001 online link. Voila! I found it easily by typing SICP in the search box. I have a computer science degree and have found this book a joy to read. Click here to read the book yourself.
-- Gustavo Garcia, June 27, 2001
A CRT can display more than 256 levels. The contrast ratio can be easily from 400 to 1000. I was looking at PC magazine site, and a 1998 report mentions Compaq 17 inch P75 monitor having CR of 1000+.Now there are LCD monitors available of course. I saw a Sony yesterday which specified its CR as 400:1! Even with some marketing hype, it is clear that there are more than 256 levels of control available. See the link in the list below.
-- Lakhinder Walia, June 27, 2001
If your primary interest is publishing large quantities of graphics online, you would do well to consider the .png format. png files provide better image quality than jpeg's because the compression algorithm is "lossless" yet their file size is comparable. The only downside is that the png format is not as widely supported as the jpg format.
For more info, go to http://www.w3.org/Graphics/PNG/
-- Percy Wegmann, July 29, 2001
Since I first saw Phillip's website in 1997, I wanted to have a website of my own.
The help offered here, including Image:Adjust:Auto Colors and Unsharp mask were most valuable to me.
I have a website now, www.robertbody.com
It's not quite the professional style like Jim's above, www.jimtardio.com , but it's mine, All mine. :)
-- Robert Body, September 22, 2001
I have a software module to add photographs to your site. Have a look at http://bali.esweb.nl and select the PhotoIndex option from the Modules menu on the left.
The software can be run as part of PHP-Nuke or standalone. For documentation look at the link, and to download the software, click here.
The next feature I will add is to allow people to vote for your photographs, and to see the best and the worst of them.
Look forward to seeing you !
Peter
-- Peter van Es, December 28, 2001