Hi Anders,
I would say that getting the WB right is most crucial, and not at all easy in mixed light…
Personally, I have tried the usual suspects ColorChecker Passport and Adobe DNG Editor. Added to that QPCard and it's own software. I have been spending some time on this recently as Tim Parkin of OnLandscape suggested I write a small article about the issue.
The way I test, is essentially shooting an IT-8 target under controlled conditions and comparing with the reference data that came with that card. In real world I have a set of profiles generated with each.
I would guess that dual illuminant profiles work probably well for continuous spectrum illumination, but spiky spectra need a special profile.
Evaluation of the images I do with the "scanin" program from Argyll CMS, which I use to generate a CGATS file that I can read into Patchtool (from Babelcolor). Patchtool can make nice comparisons, both visualising colour differences and calculating Delta E* values and statistics.
The reason I use the IT-8 target instead of ColorChecker is that it has many more patches and covers a large part of Adobe RGB.
If the ColorChecker base calibration route works or not may depend on colour preferenses. I am happy with the colour rendition of my Sonys, and I can come pretty close with the profiles I have tested.
I attach four images, the first two show the colour errors in six different cases:
Sony Alpha SLT Adobe Standrad | P45+ Adobe Standard | P45+ AdobeDNG Prfile Editor |
P45+ QPCard | P45+ ColorChecker PP | P45+ Capture One |
The third images show the deviations from my Sony Alpha 99 SLT using the ColorChecker Passport Profile while the fourth one are the deviations for Capture One. So ColorChecker Passport gives a rendition on the P45+ which is close to my Sony Alpha 99SLT, while Capture One produces different colours.
Capture One pushes some of the deep blues outside Adobe RGB, so that patch gets a DeltaE* of almost 17, but it looks perfectly OK on screen because of gamut clipping. Took me a while to figure out.
Best regards
Erik
Ps. The first draft of the article I am working on is here:
http://echophoto.dnsalias.net/ekr/Articles/OLS_OnColor/OnColor.pdfI ask mainly as a landscape photographer. I've just got this new H4D-50 camera, only using the back in on my Linhof. Previously I've been using Leaf Aptus 75. I'm now running a series of tests to see how well the H4D-50 performs compared to my Aptus 75.
As many of you know if you use the same raw converter for two cameras and generate custom profiles for daylight illuminant (using a color checker) you will get almost indistinguishable color under that light condition. I did that experiment and got the expected result. However in landscape the light is seldom plain daylight, and here in northen Sweden we have pretty extreme light during the winter season, but also during summer with midnight sun etc.
My way to work with color in landscape is to use a daylight profile regardless of light condition, and then hand-tune white balance until it looks natural and realistic according to my memory. I may tone the picture slightly for effect, but I rarely correct individual colors.
When the illuminant changes form the profiled, color rendition will modulate largely as an effect of the sensor's CFA. That is at other light I will start to see a difference between the Aptus 75 and the H4D-50. It would take me a year to go through all seasons and my typical subjects though so it's not a very efficient way to evaluate. The little tests I've done by modulating a reference light seems to suggest that while the Aptus often wants things to be greener than they should (which is what I've felt in the field too), the Hassy will make things redder, but I don't know for sure from that little testing.
The only thing I can really conclude from my testing is that color will not be exactly the same with the Hassy, but will it be better or worse, or just different? My best guess is the latter and I'm quite comfortable with that, but I don't know, and I don't know how to find out other than start using it and hoping I'm happy with it after a year (seasons here are very different in terms of light and how subjects look, now we're buried in snow).
Any ideas?