Hi, I'm using Ghostscript 9.05 to convert RGB pdf to CMYK pdf. It's converting fine as long as the RGB pdf doesn't contain any transparent image. But with transparent image conversion does fail. Followings are the used parameter and error output gswin64c.exe -o "out.pdf" -dNOPAUSE -dBATCH -dSAFER -sDEVIC E=pdfwrite -dUseCIEColor -dPDFSETTINGS=/prepress -sProcessColorModel=DeviceCMYK -sColorConversionStrategy=CMYK -sColorConversionStrategyForImages=CMYK "in.pdf" GPL Ghostscript 9.05 (2012-02-08) Copyright (C) 2010 Artifex Software, Inc. All rights reserved. This software comes with NO WARRANTY: see the file PUBLIC for details. Processing pages 1 through 2. Page 1 Error: /rangecheck in --.begintransparencygroup-- Operand stack: --dict:7/16(L)-- --dict:3/3(L)-- 0 0 432 288 Execution stack: %interp_exit .runexec2 --nostringval-- --nostringval-- --nostringval- - 2 %stopped_push --nostringval-- --nostringval-- --nostringval-- fa lse 1 %stopped_push 1926 1 3 %oparray_pop 1925 1 3 %oparray_ pop 1909 1 3 %oparray_pop --nostringval-- --nostringval-- 2 1 2 --nostringval-- %for_pos_int_continue --nostringval-- --nostringval-- false 1 %stopped_push --nostringval-- Dictionary stack: --dict:1175/1684(ro)(G)-- --dict:1/20(G)-- --dict:82/200(L)-- --dict:82 /200(L)-- --dict:109/127(ro)(G)-- --dict:291/300(ro)(G)-- --dict:24/31(L)- - --dict:6/8(L)-- --dict:21/40(L)-- Current allocation mode is local Last OS error: No such file or directory GPL Ghostscript 9.05: Unrecoverable error, exit code 1 However if I use -dNOTRANSPARENCY flag it can convert to CMYK but the quality of the transparent image is unaccaptable.
Created attachment 8730 [details] RGB pdf contins two transparent image of butterfly in first page This PDF of two page contains two transparent butterfly image in first page. when converting to CMYK color pdf the conversion is failing.
(In reply to comment #1) > Created an attachment (id=8730) [details] > RGB pdf contins two transparent image of butterfly in first page > > This PDF of two page contains two transparent butterfly image in first page. > when converting to CMYK color pdf the conversion is failing. The problem is that you are setting -dUseCIEColor, the code is unable to convert a CIEABC color space into a DeviceCMYK space. The current code (not the latest release, but the latest code in the Git repository) will emit a warning and alter the conversion strategy to 'leave color unchanged'. This will result in the images being emitted in an ICCBased colour space. This is not a bug, the code is behaving as expected. At some point we intend to rewrite the colour handling in pdfwrite and this will be addressed at that time.
(In reply to comment #2) > (In reply to comment #1) > > Created an attachment (id=8730) [details] [details] > > RGB pdf contins two transparent image of butterfly in first page > > > > This PDF of two page contains two transparent butterfly image in first page. > > when converting to CMYK color pdf the conversion is failing. > > The problem is that you are setting -dUseCIEColor, the code is unable to > convert a CIEABC color space into a DeviceCMYK space. > > The current code (not the latest release, but the latest code in the Git > repository) will emit a warning and alter the conversion strategy to 'leave > color unchanged'. This will result in the images being emitted in an ICCBased > colour space. > > This is not a bug, the code is behaving as expected. At some point we intend to > rewrite the colour handling in pdfwrite and this will be addressed at that > time. Thanks you very much. After removing -dUseCIEColor flag conversion is working well. One thing if you can give me some solution I will really appreciate it, during color conversion transparent PNGs with shadow is loosing quality on shadow. Is there anything I'm missing. Thanks in advance.
(In reply to comment #3) > Thanks you very much. After removing -dUseCIEColor flag conversion is working > well. One thing if you can give me some solution I will really appreciate it, > during color conversion transparent PNGs with shadow is loosing quality on > shadow. Is there anything I'm missing. I don't know what you mean by 'losing quality', but its probably some kind of over-aggressive downsampling or lossy image compression. If you remove -dPDFSETTINGS=/prepress does it make any difference ? I would suggest that you start with the simplest possible command line and add or alter settings one by one, in general the simplest possible command line to pdfwrite will produce the best quality result, but not the smallest possible file.
(In reply to comment #4) > I don't know what you mean by 'losing quality', but its probably some kind of > over-aggressive downsampling or lossy image compression. If you remove > -dPDFSETTINGS=/prepress does it make any difference ? > > I would suggest that you start with the simplest possible command line and add > or alter settings one by one, in general the simplest possible command line to > pdfwrite will produce the best quality result, but not the smallest possible > file. Yes, without -dPDFSETTINGS=/prepress flag converted pdf's image is getting very lossy. I'm going to try out smallest command possible. Thanks.
With the release of 9.12 this is now resolved. It is no longer necessary (and is now deprecated) to use -dUseCIEColor with pdfwrite in order to do colour management. It is also no longer necessary to set both ProcessColoModel and ColorConversionStrategy when going to a device space, the action of setting ColorConversionStrategy to a device space automatically sets ProcessColorModel to that space.