On Tue, Dec 20, 2011 at 12:19 PM, john Culleton <John at wexfordpress.com>wrote:
> On Tue, 20 Dec 2011 12:06:11 -0600 > Patrick Noffke <patrick.noffke at gmail.com> wrote: > > > > > > Because I want to experiment with different ICC profiles for the same > > sRGB colors (which will include images in addition to these > > rectangles). I want the profile to define the conversion to CMYK for > > all sRGB colors. > > > > I obtained a profile that seems to do the conversion OK. Why do > you need to create your own? I use the following profile > which also limits the ink density to 240%: > SWOPcoated5_240.icc > Available here: > http://wexfordpress.com/tex/SWOPcoated5_240.icc > > That doesn't change the problem. Scribus is still converting colors with R=G=B to black only, and nearby colors (e.g. R=0, G=1, B=0) to 4-color CMYK values. With real inks, even with a 240 max TAC, there will be a big color difference in these CMYK values. Here is the portion of the (uncompressed) PDF that results using the SWOPcoated5_240 profile: q 1 0 0 1 0 0 cm q 0 0 0 0.25098 k 0 0 0 1 K 1 w [] 0 d 0 J 0 j 1 0 0 1 40.83465 751.49291 cm 0 0 m 17.0079 0 l 17.0079 -17.0079 l 0 -17.0079 l 0 0 l h f* 0 0 m 17.0079 0 l 17.0079 -17.0079 l 0 -17.0079 l 0 0 l h S Q q 0 0 0 0.50196 k 0 0 0 1 K 1 w [] 0 d 0 J 0 j 1 0 0 1 60 751.49291 cm 0 0 m 17.0079 0 l 17.0079 -17.0079 l 0 -17.0079 l 0 0 l h f* 0 0 m 17.0079 0 l 17.0079 -17.0079 l 0 -17.0079 l 0 0 l h S Q q 0 0 0 0.74902 k 0 0 0 1 K 1 w [] 0 d 0 J 0 j 1 0 0 1 78.84252 751.49291 cm 0 0 m 17.0079 0 l 17.0079 -17.0079 l 0 -17.0079 l 0 0 l h f* 0 0 m 17.0079 0 l 17.0079 -17.0079 l 0 -17.0079 l 0 0 l h S Q q 0 0 0 1 k 0 0 0 1 K 1 w [] 0 d 0 J 0 j 1 0 0 1 97.68504 751.49291 cm 0 0 m 17.0079 0 l 17.0079 -17.0079 l 0 -17.0079 l 0 0 l h f* 0 0 m 17.0079 0 l 17.0079 -17.0079 l 0 -17.0079 l 0 0 l h S Q q 0.43529 0.4 0.51373 0.99608 k 0 0 0 1 K 1 w [] 0 d 0 J 0 j 1 0 0 1 116.52756 751.49291 cm 0 0 m 17.0079 0 l 17.0079 -17.0079 l 0 -17.0079 l 0 0 l h f* 0 0 m 17.0079 0 l 17.0079 -17.0079 l 0 -17.0079 l 0 0 l h S Q Q > Any conversion from RGB to CMYK will involve some shift in > colors. Not all RGB colors can be expressed in CMYK. > But you knew that already, right? > > Yes, I realize that. I want to convert my document to CMYK using profiles with the same gamut, but other differences that I am enforcing (e.g. different GCR). You ask why. I design color measurement devices for offset and newspaper printing presses. Lately, I'm researching how to measure TVI from an image. I need to enforce known TVI differences in the color separations from a document I create. I can do this with Matlab using (CMYK) TIFFs, but it is tedious to design my document that way, so I wanted to do it with Scribus. (I can also enforce TVI differences by modifying the ICC profile's output curves.) Thanks, Pat -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.scribus.net/pipermail/scribus/attachments/20111220/6728fe87/attachment.html>
