Change of Color space

[Sigi]

Hello,

I shoot in Raw and have sofar an sRGB based workflow. Until now I hardly printed (I used labs for that as I do not have a printer) and was very happy with the few prints I have done so far.

I want to get more into printing and I am reading up on Color Managment and printing. What I am wondering now is the following.

All my Raw files go through DXO and are sRGB tagged until now. Photoshop is also set to sRGB. Let's assume I change to Adobe RGB(1998).

1. What will happen to an old tiff file that is still sRGB?
2. Will a change to the wider gamut space actually make any send with the old tiff files I have?

Thank you in advance

Siegfried

[PeterAit]

Hello,

I shoot in Raw and have sofar an sRGB based workflow. Until now I hardly printed (I used labs for that as I do not have a printer) and was very happy with the few prints I have done so far.

I want to get more into printing and I am reading up on Color Managment and printing. What I am wondering now is the following.

All my Raw files go through DXO and are sRGB tagged until now. Photoshop is also set to sRGB. Let's assume I change to Adobe RGB(1998).

1. What will happen to an old tiff file that is still sRGB?
2. Will a change to the wider gamut space actually make any send with the old tiff files I have?

Thank you in advance

Siegfried

Better than Adobe RGB would be ProPhoto RGB, which has a wide color space.

When you process a raw file into a tiff, all the colors are forced into the color space in use. You are using sRGB, so all your tiffs will contain only colors that exist in that color space. If you open one of those tiffs and edit it using the Adobe or ProPhoto color space, it should look exactly the same because all the colors in sRGB are also in the 2 larger color spaces. But, if you do any edits that change colors, you will be able to use colors that were not in sRGB but are in the new color space. This may or may not make much of a difference depending on the edits you try to do.

[Sigi]

Better than Adobe RGB would be ProPhoto RGB, which has a wide color space.

When you process a raw file into a tiff, all the colors are forced into the color space in use. You are using sRGB, so all your tiffs will contain only colors that exist in that color space. If you open one of those tiffs and edit it using the Adobe or ProPhoto color space, it should look exactly the same because all the colors in sRGB are also in the 2 larger color spaces. But, if you do any edits that change colors, you will be able to use colors that were not in sRGB but are in the new color space. This may or may not make much of a difference depending on the edits you try to do.

Hello Peter,

so if I understand you correctly I have not "lost" any color information in my existing tiffs by using sRGB sofar. All the color information is there - just compressed in the smaller sRGB color space.

When I open the tiff file I "convert" to the new color space i.e Adobe RGB or ProPhoto RGB and it should work - correct?

Thank you

Siegfried

[Neuffy]

It will "work", yes. However, any colors that are outside the sRGB color space will not be present in the "re-expanded" file. They are indeed lost.

Hello Peter,

so if I understand you correctly I have not "lost" any color information in my existing tiffs by using sRGB sofar. All the color information is there - just compressed in the smaller sRGB color space.

When I open the tiff file I "convert" to the new color space i.e Adobe RGB or ProPhoto RGB and it should work - correct?

Thank you

Siegfried

[PeterAit]

Hello Peter,

so if I understand you correctly I have not "lost" any color information in my existing tiffs by using sRGB sofar. All the color information is there - just compressed in the smaller sRGB color space.

When I open the tiff file I "convert" to the new color space i.e Adobe RGB or ProPhoto RGB and it should work - correct?

Thank you

Siegfried

No, that's not right. When you convert from raw to sRGB you lose color information. Heck, when you convert from raw to Adobe RGB or ProPhoto you also lose color information, but you don't lose as much. Once you are in sRGB, any color outside the sRGB color space is gone forever. If you then convert from sRGB to Adobe, you don't gain colors back but you now have the potential for more colors.

Here's an analogy. Your raw image is a gallon of water. Your pour it into a 1 quart container, sRGB. Those 3 quarts that spill are lost forever. Now, you pour that quart of water from your 1 quart sRGB container into a 2 quart container (Adobe RGB). You still have only 1 quart of water (colors) but you now have the potential to add another quart of water (more colors).

I hope this makes sense!

[Jonathan Wienke]

Hello Peter,

so if I understand you correctly I have not "lost" any color information in my existing tiffs by using sRGB sofar. All the color information is there - just compressed in the smaller sRGB color space.

Nope. All colors outside sRGB were lost when you converted the RAW to sRGB. If you want them back, you'll need to go back to the original RAW file, convert it using the ProPhoto color space, and process the file all over again. I highly recommend using ProPhoto because there are monitors and printers that can handle colors outside Adobe RGB.

[Wayne Fox]

Hello Peter,

so if I understand you correctly I have not "lost" any color information in my existing tiffs by using sRGB sofar. All the color information is there - just compressed in the smaller sRGB color space.

When I open the tiff file I "convert" to the new color space i.e Adobe RGB or ProPhoto RGB and it should work - correct?

Thank you

Siegfried

Well, all of the color is there that was contained in the sRGB file.  You did lose color available in your raw file when you first converted it and forced it into the sRGB space, and that color cannot be recovered without a new raw conversion.  If you use Adobe RGB you will also most likely lose some color information, just not as much, that's why proPhotoRGB is recommended.  How significant that is depends on the image itself ... from not at all to perhaps significant.

Edit:  Looks like Jonathan and I were posting an answer at the same time

[Sigi]

Hello All,

thank your for your answers - I understand.

I will do some tests now comparing prints with sRGB workflows, AdobeRGB and ProPhoto workflows. As already mentioned in my first post I use a lab for prints as I do not have a printer of my own. The lab has very good credentials and reviews here in Germany.

Thanky you again for your advice

Siegfried

[Sigi]

deleted - somehow posted twice

[John S C]

Of course if you still have youe RAW files all the information is till there, so you could reprocess them to a different colour space if needed.

[bjanes]

I will do some tests now comparing prints with sRGB workflows, AdobeRGB and ProPhoto workflows. As already mentioned in my first post I use a lab for prints as I do not have a printer of my own. The lab has very good credentials and reviews here in Germany.

Thank you again for your advice

Siegfried, Not mentioned previously, you should use 16 bit files for ProPhotoRGB. Also, you should try to get a profile of the printer so you can use soft proofing to see if the gamut of the image is within that of the printer. Gamut mapping software such as Colorthink or Gamutvision can also map the gamut of the image and compare it to that of the working spaces and printer in a quantitative fashion. Photoshop's gamut warning simply tells you if the image is out of gamut. Such excellent devices such as the Durst Lambda or the Océ Lightjet use photographic paper and their gamut is not much beyond sRGB. High end inkjets have the largest gamut and can make use of the expanded gamut of ProPhotoRGB.

Bill

[David Saffir]

Siegfried -

Using color space can be like fighting gravity - a smaller space, sRGB, cannot successfully be transformed into Adobe 98 or Pro Photo - larger spaces. One can only go downhill, I'm sorry to say. Once converted from Adobe 98 to sRGB, for example, it can't be restored without going back to the source file and starting over.

Here's a few suggestions:

If you shoot RAW, process your image files to Adobe 98 or Pro Photo
If you need 8 bit JPEGs, process them off to a separate folder.
Keep your images in 16 bit in post-production, even through printing.
Archive your master files as layered 16-bit TIFF, or if you prefer, PSD files.
Last, keep all of your good quality RAW files in archives. Software keeps improving; you may find opportunities to re-work an old image.

David Saffir
http://davidsaffir.wordpress.com