Changing color space?

frons

I have been using Zerene Stacker to process some macro shots on my iMac. The software does have a known issue with the default Nikon sRGB 4.0.0.3001 profile on my D200, so I have been exporting the RAW files to either TIFFs or jpgs (Zerene can use either) first. I then use Capture NX2 to change the color profile to an alternate sRGB profile and save, then process in Zerene.

I am not very familiar with color profiles, so I am wondering if I am doing things properly. If I first export to jpg, then change the color profile and resave, am I losing any generational quality? Should I be making all these changes to a TIFF file only? Or, should I change the color profile in my D200 to aRGB to avoid this scenario in the first place? Any help for these (probably) basic questions would be appreciated.

MarkR

JPEG uses "lossy" compression. Anytime you re-save a jpeg, lossy compression kicks in and, as you might expect, "loses" some of the data.

TIFF, by comparison, is "lossless."

Just based on that alone, I'd stick with TIFF.

frons

Thanks, Mark. That's what I thought I had heard long ago. Guess I'll go back and re-export from the RAW files.

Anyone have thoughts on sRGB vs aRGB, at least for my purposes?

MarkR

One of the color gurus on this site will have to guide you re: color space changes.

(I believe that there is minor data loss in converting between color spaces. As to the best color space for editing-- I don't want to get dragged into that!)

pathfinder

If your software will allow, I would stick to 16 bit tiffs, in the largest color space all your software supports - this MAY be ProPhotoRGB ( this is supported by Lightroom and CS3 and CS4 for certain ). I would convert to sRGB only when you are done editing and ready to upload a file to the web for online printing.

If you are going to print your own file with a newer inkjet printer with 8 or more ink cartidges, you may prefer to keep your image in Adobe RGB. Do not use Adobe RGB unless you KNOW and UNDERSTAND why you want to use it.

frons

pathfinder wrote:

If your software will allow, I would stick to 16 bit tiffs, in the largest color space all your software supports - this MAY be ProPhotoRGB ( this is supported by Lightroom and CS3 and CS4 for certain ). I would convert to sRGB only when you are done editing and ready to upload a file to the web for online printing.

If you are going to print your own file with a newer inkjet printer with 8 or more ink cartidges, you may prefer to keep your image in Adobe RGB. Do not use Adobe RGB unless you KNOW and UNDERSTAND why you want to use it.

I am definitely in over my head on this topic; I am not printing at home, though.

Using Capture NX2, there are about a dozen other Nikon and/or Adobe color profiles, but ProPhotoRGB is not one of them. How would I find out which of my choices would be the "best"?

This may be a more important detail: selecting Apply Profile in NX2 seems to be enough to fix the problem without actually Converting to a new profile. What is being changed in my file if I only apply a new profile instead of converting?

A related question: are there pros and cons to doing any pp to the individual images before the stacking instead of applying pp to only the stacked image?

lynnma

pathfinder wrote:

If your software will allow, I would stick to 16 bit tiffs, in the largest color space all your software supports - this MAY be ProPhotoRGB ( this is supported by Lightroom and CS3 and CS4 for certain ). I would convert to sRGB only when you are done editing and ready to upload a file to the web for online printing.

If you are going to print your own file with a newer inkjet printer with 8 or more ink cartidges, you may prefer to keep your image in Adobe RGB. Do not use Adobe RGB unless you KNOW and UNDERSTAND why you want to use it.

Still in the color space mode - you mention ProPhotoRGB - is there a printer out there that will print these gamuts?

lynnma

frons wrote:

Thanks, Mark. That's what I thought I had heard long ago. Guess I'll go back and re-export from the RAW files.

Anyone have thoughts on sRGB vs aRGB, at least for my purposes?

I may get shot down for this as I'm still learning but it's my understanding that sRGB has less of a color space than RGB. But sRGB looks good on web images but does not print to a regular printer as well as RGB which has a bigger color space. Thats if you are going to print in RGB and not CMYK.

MarkR

lynnma wrote:

I may get shot down for this as I'm still learning but it's my understanding that sRGB has less of a color space than RGB. But sRGB looks good on web images but does not print to a regular printer as well as RGB which has a bigger color space. Thats if you are going to print in RGB and not CMYK.

Well, sRGB is an RGB space. So is Adobe, ProPhoto, etc.

Most web browsers are not color managed, so they ignore the ICC profile anyway. However just about anything that is color managed will understand an sRGB tag. The "s" stands for either "safe" or "stupid", depending on how useful you find it.

Many find it useful to edit in a large gamut color space (such as ProPhoto, which not coincidently is the default editing space in Lightroom) and move to AdobeRGB or sRGB for publishing the image.

Any more and you'll have to ask one of the color management gurus.