Joined: 25 Jun 2004
Location: South Bend, Indiana USA
|Posted: Wed Apr 03, 2013 9:13 am Post subject: Adobe RGB vs sRGB
Go to Ken's site and see the two images to visualize the differences in colors. (And to also donate back to him, if you found the info useful)
The same old-wives-tale about Adobe RGB having a broader range of colors has been circulating on the internet since the 1990s.
It does in theory, but not in practice.
I know this stuff. Did you know I conceived the world's first dedicated digital colorspace converter chip, the TMC2272, back in 1990 when I worked at TRW LSI Products? I've been working with the matrix math, hardware and software that does this for decades. I also coined the word "gigacolors," for use with 36-bit and 48-bit color data. I was only kidding, but the word is still used. TRW LSI was a small, ultra-creative division of TRW, and I got away putting the same mirth I use on this website into the datasheets I wrote. The industry copied us and the word lives on.
10 years ago when I was able to start doing this at home I also was all excited about Adobe RGB and a slew of other whacky, innovative color spaces. After some experimentation, even I discovered that default sRGB was plenty for everything I did, and eliminated the chance for grave errors.
Adobe RGB is irrelevant for real photography. sRGB gives better (more consistent) results and the same, or brighter, colors.
Using Adobe RGB is one of the leading causes of colors not matching between monitor and print.
sRGB is the world's default color space. Use it and everything looks great everywhere, all the time.
Adobe RGB should never be used unless you really know what you're doing and do all your printing yourself. If you really know what you're doing and working in publishing, go right ahead and use it. If you have to ask, don't even try it.
If you're one of the few a full-time career professional photographers left standing and shoot for print, by all means shoot Adobe RGB, but if you're a very serious amateur, beware.
Adobe RGB theoretically can represent a wider range (gamut) of colors, however:
1.) Adobe RGB requires special software and painstaking workflow not to screw it up. Make one mistake anyplace and you get dull colors, or worse. You cannot use Adobe RGB on the internet or for email or conventional photo lab printing. If you do, the colors are duller.
2.) I've made Lightjet, Fuji Supergloss and inkjet prints of 100% saturated ramps in both color spaces. I saw the same color range in print with each colorspace. I saw no real gain of any wider gamut in practice, even with these special tests.
I didn't see any of these printers have the ability display any of the extra gamut potentially represented by Adobe RGB.
Want to try it yourself? Steal the image above, assign it the profiles of your choice, and print away. Most of what you'll see will be colorspace conversion artifacts. if you do this correctly, both prints will look almost identical. If you see a wider gamut, go for it.
sRGB is the world standard for digital images, printing and the Internet. So long as you haven't screwed with anything, you and the world are shooting in sRGB.
Use sRGB and you'll get great, accurate colors everywhere all the time. Like what you see in my Gallery and the top grad (widest rainbow) above? That's all coming to you in sRGB. Use sRGB and you'll automatically get great, saturated and accurate color everywhere. See also Color Management is for Wimps.
sRGB is specified in IEC 61966-2.1, which you may also see when examining color profiles. That gobbledygook means the same thing as sRGB. (sRGB uses ITU BT Rec. 709 primaries and a gamma of 2.2, same as most kinds of HDTV.)
Adobe RGB squeezes colors into a smaller range (makes them duller) before recording them to your file. Special smart software is then needed to expand the colors back to where they should be when opening the file.
Since Adobe RGB squeezes colors into a smaller range, the full range represents a broader range of colors, if and only if you have the correct software to read it.
Played back on most equipment, the internet or email, the colors look duller, and when played back with the correct software, the extra chroma gain required adds a little chroma quantization noise.
This is the example above. The bottom grad is what an Adobe RGB file looks like when interpreted as sRGB, which is what happens over the internet, email, or most printers unless you're printing directly at home from Photoshop. Printed correctly the Adobe RGB grad looks the same as the sRGB grad, so I asked myself, why bother?
If you use Adobe RGB you will have to remember to convert back to sRGB for sending your prints out or sharing them on the Internet. Otherwise they look duller than sRGB!
If you have the right software to re-expand the colors you theoretically might have a slightly broader range of colors. However, if at any point in the chain you don't have the right software and haven't attached the Adobe RGB profile you'll get the duller colors as recorded!
Web browsers don't have, and print labs rarely have, the right software to read Adobe RGB This is why people who shoot it are so often disappointed. Even if a place has the right software, if you forget to add the Adobe RGB profiles to your files these places will read them incorrectly and you'll get dull colors.
Adobe RGB may be able to represent a slightly larger range of colors, but no screen or print material I've used can show this broader range, so why cause yourself all the trouble? I've experimented with 100% saturated grads in these two color spaces and never seen any broader range from Adobe RGB either on my screen or on SuperGloss Light jet prints.
Worse, if you're the sort of vacuum-operating geek who wants to shoot Adobe RGB because you read about it in a magazine article, did you realize that because the colors are compressed into a smaller range that there is more chroma quantization noise when the file is opened again? Ha!
Keeping people lost and confused sells more magazines and more new equipment, which supports magazine advertising. That's why you see so many articles on Adobe RGB elsewhere.
If you find this as helpful as a book you might have had to buy or a workshop you may have had to take, feel free to help me continue helping everyone.
Thanks for reading!