将PDF转换为CMYK（识别识别CMYK） [英] Converting PDF to CMYK (with identify recognizing CMYK)

问题描述

我很难让ImageMagick的识别，以便将PDF标识为CMYK。

I am having much trouble to get ImageMagick's identify to, well, identify a PDF as CMYK.

基本上，假设我正在构建此文件， test.tex ， pdflatex ：

Essentially, let's say I'm building this file, test.tex, with pdflatex:

\documentclass[a4paper,12pt]{article}

%% https://tex.stackexchange.com/questions/13071
\pdfcompresslevel=0

%% http://compgroups.net/comp.text.tex/Making-a-cmyk-PDF
%% ln -s /usr/share/color/icc/sRGB.icm .
% \immediate\pdfobj stream attr{/N 4} file{sRGB.icm}
% \pdfcatalog{%
% /OutputIntents [ <<
% /Type /OutputIntent
% /S/GTS_PDFA1
% /DestOutputProfile \the\pdflastobj\space 0 R
% /OutputConditionIdentifier (sRGB IEC61966-2.1)
% /Info(sRGB IEC61966-2.1)
% >> ]
% }

%% http://latex-my.blogspot.com/2010/02/cmyk-output-for-commercial-printing.html
%% https://tex.stackexchange.com/questions/9961
\usepackage[cmyk]{xcolor}

\begin{document}
Some text here...
\end{document}

如果我然后尝试识别结果 test.pdf 文件，无论我尝试过什么选项（至少根据源代码中的链接），我都把它作为RGB，然而，它的颜色将是保存为CMYK;对于上面的来源：

If I then try to identify the resulting test.pdf file, I get it as RGB, no matter what options I've tried (at least according to the links in the source) - and yet, the colors in it would be saved as CMYK; for the source above:

$ grep -ia 'cmyk\|rgb\| k' test.pdf 
0 0 0 1 k 0 0 0 1 K
0 0 0 1 k 0 0 0 1 K
0 0 0 1 k 0 0 0 1 K
0 0 0 1 k 0 0 0 1 K
FontDirectory/CMR12 known{/CMR12 findfont dup/UniqueID known{dup
/PTEX.Fullbanner (This is pdfTeX, Version 3.1415926-1.40.11-2.2 (TeX Live 2010) kpathsea version 6.0.0)

$ identify -verbose 'test.pdf[0]'
...
  Type: Palette
  Endianess: Undefined
  Colorspace: RGB
  Depth: 16/8-bit
  Channel depth:
    red: 8-bit
    green: 8-bit
    blue: 8-bit
  Channel statistics:
    Red:
...
    Green:
...
    Blue:
...
  Histogram:
         5: (12593,11565,11822) #31312D2D2E2E rgb(49,45,46)
         4: (16448,15420,15677) #40403C3C3D3D rgb(64,60,61)
         9: (20303,19275,19532) #4F4F4B4B4C4C rgb(79,75,76)
        25: (23901,23130,23387) #5D5D5A5A5B5B rgb(93,90,91)
...

如果我还取消注释，那么同样的事情也会发生 \immediate\pdfobj stream ...
part;然而，如果文档中只有一种颜色（黑色），我看不到识别在哪里提出RGB值的直方图（尽管可以说，所有这些都接近灰色）？！

The same pretty much happens if I also uncomment that \immediate\pdfobj stream ... part; and yet, if there is only one color (black) in the document, I don't see where does identify come up with a histogram of RGB values (although, arguably, all of them close to gray) ?!

 

所以没关系，然后我会尽量使用 ghostscript 将 test.pdf 转换为新的pdf，通过识别将其识别为CMYK - 但即使在那里也没有运气：

So nevermind this, then I though I'd better try to use ghostscript to convert the test.pdf into a new pdf, which would be recognized as CMYK by identify - but no luck even there:

$ gs -dNOPAUSE -dBATCH -dSAFER -sDEVICE=pdfwrite  -sOutputFile=test-gs.pdf -dUseCIEColor -sProcessColorModel=DeviceRGB -dProcessColorModel=/DeviceCMYK -sColorConversionStrategy=/CMYK test.pdf 

GPL Ghostscript 9.01 (2011-02-07)
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 1.
Page 1


$ identify -verbose 'test-gs.pdf[0]'
...
  Type: Grayscale
  Base type: Grayscale
  Endianess: Undefined
  Colorspace: RGB
  Depth: 16/8-bit
...

所以识别唯一被认为是变化的东西，是类型：灰度（来自之前的类型：调色板）;但是否则它仍会看到RGB颜色空间！

So the only thing that identify perceived as a change, is Type: Grayscale (from previous Type: Palette); but otherwise it still sees an RGB colorspace!

除此之外，请注意标识 是能够正确报告CMYK pdf - 请参阅 CMYK海报示例：将pdf页面大小拟合为（位图）图像大小？ ＃17843 - TeX - LaTeX - Stack Exchange ，用于使用 convert 和 gs 。事实上，我们可以执行：

Along with this, note that identify is capable of correctly reporting a CMYK pdf - see CMYK poster example: fitting pdf page size to (bitmap) image size? #17843 - TeX - LaTeX - Stack Exchange for a command line example of generating such a PDF file using convert and gs. In fact, we can execute:

convert test.pdf -depth 8 -colorspace cmyk -alpha Off test-c.pdf

...此 会产生一个PDF <$ strong c $ c>识别编辑为CMYK - 但是，PDF也将被栅格化（默认为72 dpi）。

... and this will result with a PDF that will be identifyed as CMYK - however, the PDF will also be rasterized (default at 72 dpi).

编辑：我刚刚发现，如果我在OpenOffice中创建.odp演示文稿，并将其导出为PDF;默认情况下，PDF将是RGB，但是，以下命令（来自 ghostscript Examples | Production Monkeys ）：

I have just discovered, that if I create an .odp presentation in OpenOffice, and export it to PDF; that PDF will by default be RGB, however, the following command (from ghostscript Examples | Production Monkeys):

# Color PDF to CMYK:
gs -dSAFER -dBATCH -dNOPAUSE -dNOCACHE -sDEVICE=pdfwrite \
-sColorConversionStrategy=CMYK -dProcessColorModel=/DeviceCMYK \
-sOutputFile=output.pdf input.pdf

...实际上会产生一个CMYK pdf，由识别报告（尽管黑色会很丰富，而不是普通的 - 在所有四个频道上）;但是，当幻灯片添加了图像时，此命令将仅 （显然，它是触发颜色转换的那个？！）！有趣的是，我无法从 pdflatex PDF获得相同的效果。

... actually will produce a CMYK pdf, reported as such by identify (although, the black will be rich, not plain - on all four channels); however, this command will work only when the slide has an added image (apparently, it is the one triggering the color conversion?!)! Funnily, I cannot get the same effect from a pdflatex PDF.

 

所以我想我的问题可以通过两种方式询问：

So I guess my question can be asked two ways:

• Linux中是否存在任何命令行转换方法，它们会将RGB pdf转换为CMYK pdf，同时保留向量，这在<$ c $中被识别为c>识别（并因此构建正确的CMYK颜色直方图）


• 是否还有其他类似于的命令行Linux工具识别，即使在 pdflatex test.pdf 中也能正确识别CMYK颜色的使用c>（并且可能构建一个颜色直方图，基于任意选择的PDF页面，如识别应该）？

• Are there any command-line conversion methods in Linux, that will convert an RGB pdf into a CMYK pdf while preserving vectors, which is recognized as such in identify (and will consequently build a correct histogram of CMYK colors)
• Are there any other command-line Linux tools similar to identify, which would recognize use of CMYK colors correctly even in the original test.pdf from pdflatex (and possibly build a color histogram, based on an arbitrarily chosen PDF page, like identify is supposed to)?

预先感谢您的回答，

干杯！

Thanks in advance for any answers,
Cheers!

  ;

一些参考：

• adobe - 脚本（或其他一些方法）将RGB转换为CMYK的PDF格式？ - Stack Overflow


• 颜色 - PDF颜色模型和LaTeX - TeX - LaTeX - Stack Exchange


• color - xcolor包的选项cmyk不生成CMYK PDF - TeX - LaTeX - Stack Exchange


• 制作cmyk PDF - comp.text.tex |计算机组


• 与ghostscript的颜色管理？ - Rhinocerus ：
  
  

• adobe - Script (or some other means) to convert RGB to CMYK in PDF? - Stack Overflow
• color - PDF colour model and LaTeX - TeX - LaTeX - Stack Exchange
• color - Option cmyk for xcolor package does not produce a CMYK PDF - TeX - LaTeX - Stack Exchange
• Making a cmyk PDF - comp.text.tex | Computer Group
• colormanagement with ghostscript ? - Rhinocerus:

例如是否指定为0 0 0
1 setcmykcolor？或者可能更像是0 0 0 setrgbcolor？在
后一种情况下，如果DeviceRGB是
重新映射到基于CIE的颜色空间，为了获得RGB图像颜色
管理，你最终会得到一个丰富的黑色文本。

Is it for instance specified as "0 0 0 1 setcmykcolor"? Or possibly rather as "0 0 0 setrgbcolor"? In the latter case you would end up with a rich black for text, if DeviceRGB is remapped to a CIE-based color space in order to get RGB images color managed.

推荐答案

sdaau，您尝试使用的命令将您的PDF转换为CMYK是不正确的。试试这个：

sdaau, the command you used for trying to convert your PDF to CMYK was not correct. Try this one instead:

 gs \
   -o test-cmyk.pdf \
   -sDEVICE=pdfwrite \
   -sProcessColorModel=DeviceCMYK \
   -sColorConversionStrategy=CMYK \
   -sColorConversionStrategyForImages=CMYK \
    test.pdf 

---

更新

如果颜色转换无法正常工作，如果您看到无法将色彩空间转换为灰色，将策略还原为LeaveColorUnchanged等消息，那么......

---

Update

If color conversion does not work as desired and if you see a message like "Unable to convert color space to Gray, reverting strategy to LeaveColorUnchanged" then...

1. 您的Ghostscript可能是 9.x版本系列中的较新版本，而


2. 您的源PDF可能会使用嵌入式 ICC颜色配置文件

1. your Ghostscript probably is a newer release from the 9.x version series, and
2. your source PDF likely uses an embedded ICC color profile

在这种情况下添加 -dOverrideICC 到命令行，看看它是否会根据需要更改结果。

In this case add -dOverrideICC to the command line and see if it changes the result as desired.

正如@Marein评论的那样，如果你想避免d出现在图像中的JPEG工件（之前没有），你应该添加

As @Marein commented, if you want to avoid JPEG artifacts appearing in the images (where there were none before), you should add

-dEncodeColorImages=false

进入命令行。

（对于几乎所有GS PDF-> PDF 处理都是如此，不仅仅是针对这种情况。因为GS默认创建一个全新的当被要求生成PDF输出时，文件包含新构造的对象和新的文件结构 - 它不仅仅是重复使用以前的对象，而是像 pdftk { pdftk 还有其他优点，不要误解我的陈述！} 。默认情况下GS应用JPEG压缩 - 看看当前 Ps2pdf文档 并搜索ColorImageFilter以了解更多详情......）

(This is true for almost all GS PDF->PDF processing, not just for this case. Because GS by default creates a completely new file with newly constructed objects and a new file structure when asked to produce PDF output -- it doesn't simply re-use the previous objects, as a more "dumb" PDF processor like pdftk does {pdftk has other advantages though, don't misunderstand my statement!}. GS applies JPEG compression by default -- look at the current Ps2pdf documentation and search for "ColorImageFilter" to learn about more details...)

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