On Feb 4, 2005, at 2:18 AM, Rob Studdert wrote:
You don't have to however if the image is mapped to Adobe RGB colour space and
you open it as if it were sRGB mapping the colours will be slightly desaturated
and slightly the wrong hues and the image will lack contrast.
If using Photoshop you can set it up to ask you what to do if the tagged colour space does not match your default working space when loading a file. You can either use the tagged space, convert to the working space, or choose not to colour manage that file. If the file is untagged it gives you the option of assigning a profile. When in doubt use sRGB - if the colours look a little bit off try opening it again as Adobe RGB.
It really depends upon your intended use for the images. If you only intend
them to be displayed on the web and not printed then sRGB is probably fine.
For web use I would say that sRGB is mandatory. It's not a rule as such, but I recommend it that strongly. Very very few web browsers support tagged images, the rest don't colour manage at all. This doesn't imply that they assume sRGB, because they're not colour managing. Theoretically you have to convert the image from sRGB (or whatever) to the monitor's colour space, which is exactly what ColorSync does on the Mac platform. However, sRGB matches most monitors pretty well so even with non colour-managed systems the colours tend to look pretty consistent. That isn't a coincidence, for reasons I won't go into. I've already written too much.
To put an Adobe RGB file on the web you should convert it to sRGB (Image - Mode - Convert to Profile). It doesn't matter too much though as very few monitors are accurately calibrated so you can feel free to ignore everything I've just written :)
Adobe RGB will allow a wider range of colours to be displayed when the image is
output on a suitably capable printer. Many of the Epson ink-jet printers won't
deliver their full colour range when fed an sRGB image.
This is correct. The Ultrachrome gamut exceeds sRGB by a country mile. I've looked a few 3D comparison plots and decided that Adobe RGB represents the best compromise for me, even though it still isn't ideal. The problem now is that monitors can't display all of Adobe RGB. There are ways around this but I'd rather not go there :)
I have recently heard speculation of LCD screens with LED backlighting in development that can do Adobe RGB. I don't know how far away from the market they are though.
Various colour spaces (including sRGB and Adobe RGB) and device profiles can be
compared graphically using the following utility. I hope this helps.
http://www.iccview.de/index_eng.htm
Mac users can use the ColorSync Utility but I think the plotting function only came in OS X 10.3. I'd provide a link of some plots I did a while ago, but I seem to have deleted the files :(
Cheers,
- Dave
http://www.digistar.com/~dmann/
