On samedi 25 février 2017 01:38:01 CET Marcus Sundman wrote: > Well, first we need sensible support for color cards in darktable. (Now > you have to go through crazy many hoops to set your whitebalance from a > color card, including multiple import/export and profile generation in > an external program and custom command line tools and whatnot.)
First you need a correctly calibrated and profiled screen (and printer if you plan on printing). Without that, you'd have to work strictly by the numbers, because there's no way you can visualise the final result. (OK, if you publish on the web, >90% of the viewers won't have a profiled screen, but at least you know how it should look) Then, setting your white balance from a *colour* card is looking for trouble (if it is at all possible to get any decent white balance from such a card). As has been said already, for a white balance, you need a neutral spot in your image: light or dark gray, but not white or black. (Such a spot can of course be a *neutral* spot on your colour card). Remember that 'setting the white balance' means changing the ratios green/red and green/blue (in practice, green is set to 1.0, and the red and blue channels are multiplied by one value each, depending on colour temperature and tint, DT _shows_ those multipliers in the white balance module, and allows you to change them directly). When you have that neutral spot in your image, in DT it's just a matter of choosing the "spot" mode in the white balance module and select a rectangle on the neutral spot. The colour patches are used to create a *camera profile*, and yes, this needs an external programme (or two), just like screen or printer profiling. *Unlike* screen and printer profiling, it's something that's mostly needed for very colour critical work. (the few times I bothered with a camera profile, the results with a custom profile were identical or nearly identical to the default profile and I had no way to show which was better) And when you get to that level, you also have to be very careful about your lights all having the same colour, as the colour of the incoming lights influences what the camera "sees". And just a small question: is there *any* raw developer that includes the possibility to generate an input profile from a colour card? Remco ____________________________________________________________________________ darktable user mailing list to unsubscribe send a mail to darktable-user+unsubscr...@lists.darktable.org
