ghostscript:将PDF转换为保留纯黑色文本的CMYK [英] ghostscript: convert PDF into CMYK preserving pure Black for text

问题描述

我需要将RGB PDF转换为CMYK PDF.

I need to convert RGB PDF into CMYK PDF.

我需要使用纯黑色的文本.

I need to have pure black color for texts.

似乎(由于下面的评论)术语黑点补偿"是错误的.我从Adobe Acrobat那里获得了它，它在我需要的地方可以正常工作.我以为gs具有相同的功能.

It seems (thanks to comments below) term "black point compensation" is wrong. I took it from Adobe Acrobat where it works exactly how i need. I thought gs has same feature.

我使用ghostscript 9.16

I use ghostscript 9.16

如果我做对了，可以使用-dBlackPtComp选项，但是它对我不起作用. 我尝试过的Ghostscript命令是:

If i got it right there is -dBlackPtComp option, but it does not work for me. Ghostscript command I have tried is:

"c:/Program Files/gs/gs9.16/bin/GSWIN64C.EXE" -o testing_black_cmyk.pdf -sColorConversionStrategy=CMYK -sDEVICE=pdfwrite -dOverrideICC=true -sOutputICCProfile=c:/Windows/System32/spool/drivers/color/JapanColor2002Newspaper.icc -dTextBlackPt=1 -dBlackPtComp=1 test2.pdf

推荐答案

尝试一下:

collink -v -G AppleRGB.icc JapanColor2002Newspaper.icc apple_to_jNP_photo.icc

collink -v -f AppleRGB.icc JapanColor2002Newspaper.icc apple_to_jNP_neutrals.icc

control.txt:

control.txt:

Image_RGB   apple_to_jNP_photo.icc       0   1   0
Graphic_RGB apple_to_jNP_neutrals.icc    0   1   0
Text_RGB    apple_to_jNP_neutrals.icc    0   1   0

和

gswin32c -q -sDEVICE=pdfwrite -o out.pdf -sColorConversionStrategy=CMYK -sSourceObjectICC=control.txt in.pdf

然后将源PDF中的DeviceRGB转换为DeviceCMYK，并且RGB 0/0/0变为(正如我现在正在检查的)DeviceGray 0，应该可以(以及其他所有中性RGB)阴影也映射到真实的灰度).

Then the DeviceRGB in source PDF is converted to DeviceCMYK, and RGB 0/0/0 becomes (as I'm checking now) the DeviceGray 0, which should be OK (and all other neutral RGB shades are mapped to true grayscale, too).

我们对不同的对象使用不同的DL配置文件的原因是，尽管饱和色彩(远离中性色)会通过两个配置文件转换为相同的CMYK，但是您可能不希望颜色突然切换为0/0/0/n在连续色调照片中，如果颜色恰好接近中性-在印刷机上看起来会很糟糕.

The reason we are using different DL-profiles for different objects, is because, though saturated colors (far from neutrals) will be converted to the same CMYK through both profiles, nevertheless you probably don't want color suddenly switch to 0/0/0/n in continuous tone photographs, if color happens to be near neutral -- it'll look terrible on the press.

例如，如果您的图像"是光栅化具有0/0/0 RGB的图形(图表等)，那么您也可以考虑对这些图像使用apple_to_jNP_neutrals.icc.

If your "images" are e.g. rasterized graphics (diagrams, etc.) with 0/0/0 RGB, then you can consider using apple_to_jNP_neutrals.icc for these images too.

如果您的页面同时包含真实图像和光栅化图形(文本)，那么运气不好，您将不得不妥协.

If your page has a mix of both real images and rasterized graphics (text) - bad luck, you'll have to compromise.

之所以使用-G而不是快速简单的Simple Mode，是因为-f(用于第二个配置文件)暗示了使用反向配置文件A2B的色域映射模式" ，我们想要2个配置文件使结果(对于饱和色)尽可能地接近.

The reason we use -G instead of fast and simple Simple Mode, is because -f (for second profile) implies the "Gamut Mapping Mode using inverse outprofile A2B", and we want 2 profiles to produce the result (for saturated colors) as close to each other as possible.

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