Originally reported by: alexcher@users.sourceforge.net pdfwrite doesn't convert images to grayscale in DeviceGray color model. Vector objects are converted to gray. From time to time users ask how to convert PS or PDF to grayscale. GS might be the answer. OTOH some users prefer to preserve original color spaces. Probably GS needs an option.
Comment originally by lpd@users.sourceforge.net Logged In: YES user_id=8861 We think the normal mode of pdfwrite should be exactly the same as Acrobat Distiller, namely, to preserve all the original color spaces (except if the user asks for device color spaces to be converted to device independent). From this point of view, the fact that pdfwrite converts vectors and text to a single, user-defined color space (Gray/RGB/CMYK) is a bug -- unfortunately, one that has been architecturally very inconvenient to fix. pdfwrite might also choose to offer an option for converting all colors, including those in images and shadings, to a user-defined color space; however, this would be a substantial amount of work to implement, and would be of limited utility.
Comment originally by jackiem@users.sourceforge.net Logged In: YES user_id=206537 Perhaps putting this in issues.htm is appropriate and closing the bug?
Comment originally by lpd@users.sourceforge.net Logged In: YES user_id=8861 I've changed the documentation of the ProcessColorModel parameter in doc/Ps2pdf.htm to state even more explicitly that this parameter does not affect images. (This was documented before, but not at the place where this parameter was defined.) I'll also add an entry to Issues.htm.
The following options -dPDFSETTINGS#/prepress -dProcessColorModel#/DeviceGray to pdfwrite leave RGB color of vector image unchanged in GS8.54 and 8.56, but work fine with GS7.05