2011/3/21 Jacek Poplawski <jacekpoplawski@xxxxxxxxx>: > On Mon, Mar 21, 2011 at 11:30 PM, gespertino@xxxxxxxxx > <gespertino@xxxxxxxxx> wrote: >> Most of the people ask for CMYK because: > > I need CMYK support for photo retouch, to create better colors. > CMYK is no different than LAB, HSV or RGB. Well, CMYK is quite different than LAB actually. Could you please elaborate about how you can create better color in a colorspace which is device dependent and has tipically a smaller gamut than most of the RGB working spaces? When you work in CMYK mode in a program like Photoshop, the visual feedback you get is an on-screen soft-proof of the CMYK color converted to your working RGB profile. So what you see isn't really what you get, and it's probably better idea to do your photo retouching in RGB soft-proofing to your target CMYK. The good thing about this is that you'll keep the larger gamut and your colors won't be unnecessarily and irreversibly clipped to a smaller gamut. CMYK (and it's not just me saying this) is an output colorspace to send images to four-inks process printers. With color management the CMYK mode should be legacy. > It is colorspace like > others, but uses 4 channels instead 3. That's not completely true. If inks were perfect, the fourth channel wouldn't be necessary. Black was added to compensate CMY inks imperfections and also to save ink and make prints cheaper. Tell me if that's not a declaration of device-dependent colorspace! When it comes to monitors, it's obvious you need to work in a device dependent colorspace. You can't use another device to see your images when you manipulate them, so there's a reasonable excuse to use device dependent colorspaces as working profiles in that case. But how your RGB image is separated to CMYK is defined in the target profile. Messing with those separations individually is modifying the way they were separated by the profile, which is the one in charge of converting the colors to the best possible values for the target device. Despite it's a pretty common practice, it doesn't sound correct. > Instead focusing on CMYK I would give Gimp access to use any defined > colorspace in realtime, just as RGB. ... > So adding support to display group of layers as RGB/LAB/HSV/CMYK could > be good first step. As far as I know (please correct me if I'm wrong), the idea with GEGL is to work in device-independent, 32bpc float linear space and then go to Lab, RGB (or even CMYK) depending on the need. So the first step you mention is on the works. What I discussed in my previous message was an interim solution mostly for black generation and pure CMYK primaries, the things that management won't solve exactly as the user wants. Gez. _______________________________________________ Gimp-developer mailing list Gimp-developer@xxxxxxxxxxxxxxxxxxxxxx https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-developer
