Quick Vuescan Question

[Stealth3kpl]

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When I output a linear raw scan there is no profile embedded despite selecting "output Colour Space Adobe RGB". Is this just assigning a profile rather than embedding one?

Pete

[tgray]

Quick answer - if the file has no profile at all, Vuescan isn't assigning one. Assigning a profile just tacks on a profile to a file, using whatever RGB values are defined in the file. Converting to a profile takes the RGB numbers in the file, and translates them to the new profile. It also hopefully embeds the profile, but that isn't always the case.

 

I don't think a linear raw scan really has a colorspace to speak of. I mean it does, but its certainly not Adobe RGB. Adobe RGB doesn't have a gamma of 1 first off. Secondly, the scanner's natural color space (ignoring the gamma issue) likely isn't the same as Adobe RGB or any other working space.

 

I'm not sure if Vuescan does any meaningful conversion of the color data it receives from the scanner before writing it to a file, or if it just assigns a color space to it. One thing to maybe test is to scan an image (non linear raw) and set the color space to sRGB. Then output it again as Adobe RGB. If the in-gamut colors are approximately the same in the two files, then I would think that Vuescan is actually converting the scanner data to the output color space. If the Adobe RGB image is uniformly more saturated, and looks exactly the same as the sRGB image when you assign the AdobeRGB image (not convert it) an sRGB profile, then I'd guess that Vuescan is just assigning an output profile, and not actually converting the scanner data.

 

All that being said, for color negative film, I think you are best just doing what looks good. Bring your raw scan into your editing program and assign it whichever profile you like, and then make adjustments until the image looks good to your eye. If you are shooting slide film, save your self all this hassle and get a calibration target. Scan that, generate a profile for your scanner and that film, and assign that profile to your scans. Then convert them to AdobeRGB or sRGB and edit away.

[Stealth3kpl]

Thanks Tim. From a conversation with ColorPerfect chaps a few months ago, I seem to recall that it's just tagged by assigning a profile.

By the way, I sent you a PM on the DPUG forum.

Cheers,

Pete