Photoshop colour space?

[robh]

I have been using sRGB colour space with photoshop and have been happy with the results (on screen and prints). I have been reading it is better to use Adobe RGB 1988 colour space instead as it has a wider gamut and gives better prints. Most of my work is from a G3 using RAW images converted with Breezebrowser (can't get the colours right with photoshops RAW conversion..)

Does anyone have any thoughts/comments on this please?

[Roger_Cavanagh]

Rob,

Adobe RGB is a larger colour space, mainly in the cyans/greens and yellow/greens and a bit in the orange/red/magentas. So if you take pictures that contain these colours, you may see a difference in prints, if your print profile also contains these colours.

You're unlikely to see much difference on screen because monitor profiles tend to be similar to sRGB.

Personally, I like to use a large colour space - ProPhoto RGB - to avoid any possibility of clipping. Using Adobe RGB should not make your workflow any more complicated, so why not use it and get the benefit of the increased gamut when you can.

Regards.

[toglenn]

Roger,
I've read several times about your use of ProPhoto and it's larger color space. I have noticed that files saved in that format are larger so I know there is more data but I'm not sure of what good is the extra color space.

Can a monitor actually display the extra space or can a printer reproduce it?

toglenn

[4walls]

The only thing is the colorspace of your print service. Try the AdobeRGB, but you may find that the colors go a little wonky with some developers. Costco around my place does not like the AdobeRGB, the colors in the prints look all wrong. So when I print there, I use sRGB.

[Roger_Cavanagh]

Roger,
I've read several times about your use of ProPhoto and it's larger color space. I have noticed that files saved in that format are larger so I know there is more data but I'm not sure of what good is the extra color space.

Using PPRGB doesn't per se add to file size. Like Adobe RGB, PPRGB only takes about 1k when it's embedded in an image file. Saving an image in some lossless uncompressed format like TIFF, files will be the same size.

I'm not sure how compression would be affected. While PPRGB has more colour, it doesn't have more colours as the number of values per RGB channel doesn't change.

Can a monitor actually display the extra space or can a printer reproduce it?

toglenn

Most monitors won't display the extra colour, but some print profiles certainly can. My view is that, if it doesn't cost anything to keep the extra data, why not keep it for those occasions when you get the benefit. And, you never know what enhancements will appear in the future.

It's a trivial matter to convert from PPRGB to an output space for printing. I don't know much about the printers that places like CostCo use, but from what I read by people like Andrew Rodney and Ethan Hansen (some links to these guys here (http://www.rogercavanagh.com/links/links-06_colourmanagement.htm)) the printers used in these places are often capable of wider gamuts than sRGB, but the service supplier is either too lazy, too ignorant to do better or deliberately catering to the lowest common denominator.

Regards,

[scottbergerphoto]

Rob,

Adobe RGB is a larger colour space, mainly in the cyans/greens and yellow/greens and a bit in the orange/red/magentas. So if you take pictures that contain these colours, you may see a difference in prints, if your print profile also contains these colours.

You're unlikely to see much difference on screen because monitor profiles tend to be similar to sRGB.

Personally, I like to use a large colour space - ProPhoto RGB - to avoid any possibility of clipping. Using Adobe RGB should not make your workflow any more complicated, so why not use it and get the benefit of the increased gamut when you can.

Regards.
Roger,
A question if you please.
What do you gain by shooting Adobe RGB (1998), and then converting to ProPhoto? Aren't you limited to the colors you captured in Adobe RGB (1998)?
Thanks in advance,
Scott

[Roger_Cavanagh]

Roger,
A question if you please.
What do you gain by shooting Adobe RGB (1998), and then converting to ProPhoto? Aren't you limited to the colors you captured in Adobe RGB (1998)?
Thanks in advance,
Scott

Scott,

I use C1 and convert to ProPhoto RGB (Camera Raw can do this too). The colour space setting in-camera does not constrain or affect the data that are captured. It's only the Canon conversion software that reduces the conversion options to Adobe or sRGB. CR gives four choices, but C1 uses profiles in such a way that you could convert to any colour space you like.

Regards,

[scottbergerphoto]

Thanks Roger. From what you are saying, I understand that to mean that a raw file can be coverted to any of the various color spaces. That leads me to two more questions:
1. Once that file has been converted to a tiff file with a color profile embedded does it make any sense at that point to change the color profile, say sRGB to Adobe RGB?(smaller to larger color gamut)
2. If the raw data can be converted to any available color space, then what's the point of choosing sRGB or Adobe RGB in the camera?
Scott

[Roger_Cavanagh]

Thanks Roger. From what you are saying, I understand that to mean that a raw file can be coverted to any of the various color spaces. That leads me to two more questions:
1. Once that file has been converted to a tiff file with a color profile embedded does it make any sense at that point to change the color profile, say sRGB to Adobe RGB?(smaller to larger color gamut)

No, because you have already clipped the colours by converting to the smaller space.

2. If the raw data can be converted to any available color space, then what's the point of choosing sRGB or Adobe RGB in the camera?
Scott

If you are not using the embedded JPG, then the camera setting is irrelevant because you can always change your mind at time of conversion. If you are using Canon software, then the camera setting may be a handy default.

Obviously, if you shoot JPG or make any use of the embedded JPG, then you should choose settings appropriate to that requirement.

Regards,

[robh]

Thanks for all the comments.

I'll try Adobe RGB to start with and see how I get on.

I do my own printing, so am not bothered with the ways labs handle the colour. I use an epson printer and since getting all the colour profiles for the different papers I find my prints are better than what the local labs can do anyway and are more consistent with different paper types. (just wish I had worked out these ICC's years ago... )

[scottbergerphoto]

Roger,
Thanks for the education tonight. You really taught me something. It makes alot of sense. The color space is a way of interpreting the raw numbers. As long as you have the raw file you can choose whatever color space you want. Another advantage to shooting RAW.
Thanks again,
Scott

[toglenn]

Roger, you said "Using PPRGB doesn't per se add to file size. Like Adobe RGB, PPRGB only takes about 1k when it's embedded in an image file. Saving an image in some lossless uncompressed format like TIFF, files will be the same size."

I took a file that was ARGB and Assigned ProPhoto and when saved, it was 16KB larger. Why?

toglenn

[Roger_Cavanagh]

Roger, you said "Using PPRGB doesn't per se add to file size. Like Adobe RGB, PPRGB only takes about 1k when it's embedded in an image file. Saving an image in some lossless uncompressed format like TIFF, files will be the same size."

I took a file that was ARGB and Assigned ProPhoto and when saved, it was 16KB larger. Why?

toglenn

Right, I've explored a bit, and my tests seems to support this conclusion. It's is nothing to do with colour spaces per se, but the actual conversion process. The default option when when converting from one space to another is to have dither checked. What dither does is reduce the chances of posterisation by "mxiing up" the colours a bit. So you may get colours in the target that weren't there in the source. They won't be very different, but this increases the colour count and so the file size.

This only applies to 8-bit files as dithering is not an option in 16-bit. It doesn't matter which direction you do the conversion, dithering may add more colours and increase the resulting file size. I didn't find any difference in 16-bit file size whatever the colour space.

So ProPhoto RGB does not increase file size just because it is a larger colour space.

Regards,

[toglenn]

Thanks Roger,

I think that answers my question. I've noticed different effects from ProPhoto, depending on the photo. In some the colors intensify and others show little or no change.

It's an interesting alternative and fun to play with!

toglenn

[marcel wouters]

Hi,
The resulting size after conversion is the pic size + the profile size (if saved with "embedded profile"), save without the profile to see the #!
The profile size has nothing to do with the color space size, it only depends from the profile content!
Ge nerally workspace profile (TRC profiles) are very compact, but print profiles as for frontier laser printers could be usually as big as 800KB.
However the pic sent to the online lab could be saved without the profile (in most cases) as the laser printer works directly on the RGB value.