This might be kind of boring information, but might be useful for researchers who've stumbled upon this page.
Every single gameboy camera photo has been modified in some way so that they conform to a standard color palette of #000000, #606060, #A8A8A8, and #FFFFFF. A number of photos on diplay were saved by the original photographers in a compressed lossy fashion, but I have restored them back to being in exactly 2-bit color. Many of these restored photos probably are not 100% accurate to how they originally were stored on a Gameboy, but I estimate that I have been at least 98% accurate in restoring them. Much of the restored photos however, are probably 100% accurate.
The techniques I used for restoring the Gameboy Camera photos were significantly manual, and involved a tiny amount of educated guesswork. Game Maker 8 was the program used to restore photos back to true 2-bit color. A tool was used to replace small ranges of colors with single colors. This tool was able to eliminate compression artifacts, and blur. When restoring a photo, it was fairly easy to figure out, which colors were supposed to be replaced by one of four color values. Other times it was not, so I had to make a guess as to what 2-bit color some pixels in the image originally belonged too.
A handful of "Gameboy Camera photos" were actually not taken on a Gameboy Camera, and these include image numbers 11, 12, 23, and possibly number 22. I have forgotten why I have included these pseudo Gameboy Camera photos originally, but the intent of this page originally was not that focused on being an archive.
I have written a blog post about my efforts on preserving these photos on the internet before they are lost forever. Due to me not keeping track of the original sources of all the images early on, I have been unable to attach sources to all Gameboy Camera Photos. It is likely some of the lost sources to these images may no longer be accessible on the internet, or may be hidden somewhere in the archives of the Wayback Machine. I have been able to trace back the original sources of many images using Google image search in the past, but Google has removed a highly useful feature in thier image search, making finding the original sources more difficult. This feature allowed you to search by exact image size which was perfect since almost every Gameboy Camera photo is 118x112 pixels. It's a good thing I saved a bunch of photos while I could. If you want even more Gameboy Camera photos, I have compiled a list of sites where I have found them. All (I might have missed one or two) links are backed up in the Wayback Machine.