My photo editing is mostly aimed at producing printed output. I have a fairly good ink-jet photo printer that I use for that purpose. Therefore, soft-proofing is a feature of Rawtherapee (RT) that particularly interests me. It has also caused me to want to learn how to best utilize the Color Management profiling features of RT. With respect to “Output Profiles” Rawpedia says, “For best printout quality, after you have tweaked your photo using soft-proofing, you should select your printer profile as the output profile and save the image using it.”. The results of doing this were both unexpected and as best I can tell undesirable.
The scenario for my initial experiment was as follows:
Perform a limited amount of editing (i.e., Exposure Tab>Exposure>Auto Levels) on a raw file and then soft-proof the result using an ICC profile (CP) supplied by Canon for my printer using a selected type of Canon photo paper. The soft-proof involved some modest amount of Highlight Compression to remove some clipped highlights. While not necessarily optimal the preview of the image looked pretty good. The result was then exported in TIF format to 2 different files. The first version specified “Output Profile = RT_sRGB” (i.e., the RT default), the second version specified an “Output Profile = CP”. In that, the only difference between the 2 exported files was the value used for the Output Profile.
When these 2 versions of the same photo are opened in some other viewers, notably PICASA & XnViewMP, they look conspicuously different. The one with RT_sRGB looks like it did in RT, which I’ll call GOOD. However, the other one does not resemble the file in RT, which I’ll call BAD. Both files looked the same when opened and viewed by RT. By the way, when opening both files in GIMP (without doing the requested conversion of profile) I can see no difference and they resemble GOOD. I realize that Rawpedia says, “The effects the output profile has on the image cannot be seen in the preview.”. However, the whole idea of soft-proof is to see an image displayed on the screen as it will look when printed and that is what I’m calling GOOD.
Next step was to compare what the 2 versions looked like when printed. The result being, GOOD looked like GOOD (i.e., what was shown by RT using soft-proof) and BAD looked like BAD (i.e., as viewed by some viewers).
That leaves me pretty confused and surely not getting what I thought was described in Rawpedia for Output Profiles.
Another point of confusion that this raises is the whole idea of what is intended for Output Profiles to do. For example, the Windows 7 computer on which the above experiment was performed has both RT and the subject Canon printer installed on it. As a result, the underlying OS knows about and can find the subject ICC profiles (both RT_sRGB & CB) whereas that is most unlikely on other computers that might be used for viewing these files. I have gone to other computers, including both Windows and Linux based, on which neither RT nor the printer software have been installed and the viewers I’ve been able to try show no difference between the 2 versions of this photo.