CMYK support
CMYK support
I notice CMYK support is lacking on TIFF file import. Is that a planned feature? When K black gets converted to rich RGB black and then back to CMYK, it ends up a 4 color black instead of 1 plate black. Not important for this project, but that's a major stumbling block for high quality printing from results (the National Geographic example I used in my post, for instance). I guess work around for now is to rip out 4 tiffs exactly the same size and georef them at the same time as a stack and then recombine? Yes, that works.
Re: CMYK support
Interestingly, the rendering/reprojection side of Geocart can handle CMYK (+Alpha!), but it’s not in use presently. It would take a fair bit of work to get other parts of the application to handle it gracefully. We weren’t sure how much interest there was. Good to know someone cares.
Presumably you don’t need to be able to specify CMYK throughout, such as in line styles?
Presumably you don’t need to be able to specify CMYK throughout, such as in line styles?
Re: CMYK support
I would be fine with raster-only support for CMYK. I'm never going to be going to press directly from Geocart for vectors, they'll be restyled in Illustrator, etc.
What happens when RGB lines get blended with CMYK raster on raster export, though? You'd need a dialog to alert user that that isn't allowed but do they want to export two rasters, one with CMYK and one with the lineswork in RGB?
To support CMYK raster quickly, since it is already there behind the scenes, I'm fine with warning the user about mixing color modes and disallowing some options when in a mixed color mode document. But I'd still need to use the linework in RGB while using a CMYK image for the georeferencing, so you couldn't just turn off lines.
What happens when RGB lines get blended with CMYK raster on raster export, though? You'd need a dialog to alert user that that isn't allowed but do they want to export two rasters, one with CMYK and one with the lineswork in RGB?
To support CMYK raster quickly, since it is already there behind the scenes, I'm fine with warning the user about mixing color modes and disallowing some options when in a mixed color mode document. But I'd still need to use the linework in RGB while using a CMYK image for the georeferencing, so you couldn't just turn off lines.
Re: CMYK support
Okay. Lots to ponder here. Hopefully others weigh in. CMYK, and color conversion in general, is not to be done naïvely, so I would expect support for it in the longer term, rather than shorter, unless a lot of people need it. Our thinking on first release was that people should let the specialized, highly refined tools deal with that issue (e.g., Photoshop) where you have known color management behaviors and flexible conversion options to RGB. Then you can return the output to Photoshop if you need CMYK downstream. CMYK->RGB->CMYK does not round-trip in general because the intersection of the gamuts loses some area. It may be that, on the Geocart side, we support L*a*b space rather than CMYK, since this gives much better results than CMYK for reprojection anyway, and it can provide virtually lossless conversion between RGB and CMYK over on the Photoshop side.