如何使用ImageMagick生成灰度PAM文件？

Question

使用 imagemagick 生成 P5 PGM / P6 PPM 是微不足道的，简单地使用

$ convert -depth 12 -size 512x512 xc:white white12.pgm
$ convert -depth 12 -size 512x512 xc:white white12.ppm

哪个正确给出：

% head -3 white12.ppm white12.pgm
==> white12.ppm <==
P6
512 512
4095

==> white12.pgm <==
P5
512 512
4095

现在我正在努力获取 PAM：P7 + 灰度工作，我能找到的是：

$ convert -depth 12 -size 512x512 xc:white white12.pam

它给出了 RGB 一个：

% head -7 white12.pam
P7
WIDTH 512
HEIGHT 512
DEPTH 3
MAXVAL 4095
TUPLTYPE RGB
ENDHDR

如何生成GRAYSCALE帕姆一？

---

我确实向上游报告了一个错误，也许我的 imagemagick 版本中有一些虚假内容：

• https://github .com/ImageMagick/ImageMagick/issues/5027

Answer 1

我认为 ImageMagick 中有一个错误。这可能是一个解决方法：

magick -depth 12 -size 512x512 gradient: -colorspace gray -compress none pgm:- | awk '
   NR==2 {w=$1; h=$2}     # pick up and save height and width on line 2
   NR<4  {next}           # ignore lines 1-3
   NR==4 {printf("P7\nWIDTH %d\nHEIGHT %d\nDEPTH 1\nMAXVAL 4095\nTUPLTYPE GRAYSCALE\nENDHDR\n", w,h);}
   1                      # pass remaining lines through unchanged' > result.pam

产生这一点：

P7
WIDTH 512
HEIGHT 512
DEPTH 1
MAXVAL 4095
TUPLTYPE GRAYSCALE
ENDHDR
65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 

Answer 2

在ImageMagick中，要创建文本格式NetPBM文件，请添加-compress无。

convert -depth 12 -size 512x512 xc:white -compress none white12.pam

head -7 white12.pam
P7
WIDTH 512
HEIGHT 512
DEPTH 3
MAXVAL 4095
TUPLTYPE RGB
ENDHDR