It looks like it might also be possible with RawTherapee. I’ve since found out it’s possible to include the IT-8 calibration as part of a workflow using VueScan on the Nikon NEF files. I was wondering what people do for camera scanning. For scanners this was typically removed by calibrating against IT-8 targets. The scanning of slide film with a scanner or camera introduces errors in the colours. I’m really meaning here scanning of slide film, not negative film. If we are talking about removing the colour cast of base stock, it is true that VuScan (and possibly others) have profiles that allow for the removal of the orangey cast on colour negative film - however, this can easily be replicated by simply including some of the film below the sprocket line in the RAW photograph and then setting that colour as white. Well, of course, none of us really knows how someone else perceives a particular shade. If you had daylight film shot under tungsten light and then digitally white balanced you’d get a image that looked like it was shot with tungsten balanced film, whereas if you can calibrate the scanning process then the digital copy would have the (correct) orange colour cast of the slide. That seems to be what most people do (or adjust colours to taste) but that corrects for the scene colour cast, whereas I’m interested in removing the colour cast in the camera copying process as I do for my scanner. I shoot RAW then correct the white balance on something white/grey in the frame. This isn't something I tend to do, other than spotting to remove dust etc. Once all this colour correction is in place then it is possible to post process the final image to taste. These targets are (relatively) cheap, however targets for Kodachrome are around £700 because it is impossible to make new ones. Now IT-8 targets are available for different types of film, for example the one above was made with Fuji Provia film, although others are available printed on Ektachrome. Using a IT-8 callibration is one way of removing these differences - a IT-8 target like the one below is scanned and then the values in each square are compared against a set of standard values (which are different for each batch of targets). That is something that I've never seen addressed in camera scanning - whether the demosaicing and processing assumptions that are made are valid when scanning colour film (I'm assuming slide film here - the differences in negative film inversion software are likely orders of magnitude greater). The spectrum of the short wavelength cones in particular varies from one person to another. Camera manufacturers have a bit of choice over the exact spectra of the dyes, and so of course do film makers.Īnd then, what you think is "best" will depend on your monitor. It will depend on how the dyes in the colour mosaic on the sensor line up with the yellow, magenta and cyan dyes in the film. One of the things I'd noticed with camera copying of modern slides was that the colours were not as good as using the (calibrated) Plustek. The corrected version looks more like I would expect. I've now found you can do this in VueScan, instructions are here - Ī couple of sample images (Ektachrome 400, Regents Park, London - copied with Nikon D610, ES1, converted from NEF file) I have seen articles from people using IT-8 targets to calibrate cameras for slide scanning, but I’m interested if anyone actually does this outside of museums etc. Ideally you would have a different IT-8 profile for each film type but unless you’re doing this professionally it would be hard to justify (particularly for Kodachrome). It’s worth adding that the purpose of the IT-8 target isn’t to get the correct “scene” colours (is what I’ve got digitally what I saw when I took the photo?) it’s to remove the effect of the scanner bias. When I’ve done camera scanning of slides I’ve noticed that the colour can be different than with the Plustek, so how do you calibrate the camera workflow for slides ? Not for Kodachrome as I can’t afford the €700 for a Kodachrome calibration target, but for everything else I use the IT-8 target that comes with Silverfast Ai. When I scan slides on my Plustek I use an IT-8 target to calibrate the colours. This is really a question for people doing camera scanning of colour slides. As there’s a few scanning threads open I’ll start a new one
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