加入2个PNG时，ImageMagick会保留自定义调色板 [英] ImageMagick preserve custom palette when joining 2 PNGs
本文介绍了加入2个PNG时，ImageMagick会保留自定义调色板的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我需要加入2个PNG图像，16个调色板，保持颜色编号和顺序作为原件。
I need to join 2 PNG images, with 16 color palette, keep colors number and order as originals.
两个PNG使用相同的16色调色板。
Both PNGs use the same 16 color palette.
有一种方法可以创建具有所有颜色的4位索引PNG，按照确切的顺序，甚至在每个PNG中都未使用？
There is a way to create 4 bit indexed PNG with all colors, in exact order, even unused in each PNG?
编辑更清晰：
我有2张照片。
第一个是level-000.png：
I have 2 pictures. The first is "level-000.png":
标识为：
Image: level-000.png
Format: PNG (Portable Network Graphics)
Mime type: image/png
Class: PseudoClass
Geometry: 144x144+0+0
Resolution: 28.35x28.35
Print size: 5.07937x5.07937
Units: PixelsPerCentimeter
Type: Palette
Endianess: Undefined
Colorspace: sRGB
Depth: 8-bit
Channel depth:
red: 8-bit
green: 8-bit
blue: 8-bit
Channel statistics:
Pixels: 20736
Red:
min: 0 (0)
max: 184 (0.721569)
mean: 88.6151 (0.34751)
standard deviation: 27.9329 (0.109541)
kurtosis: 1.7675
skewness: 0.143857
Green:
min: 0 (0)
max: 199 (0.780392)
mean: 68.8957 (0.270179)
standard deviation: 22.7411 (0.0891808)
kurtosis: 18.2722
skewness: 2.87959
Blue:
min: 0 (0)
max: 111 (0.435294)
mean: 19.4671 (0.0763416)
standard deviation: 22.1775 (0.0869706)
kurtosis: 2.80475
skewness: 1.17593
Image statistics:
Overall:
min: 0 (0)
max: 199 (0.780392)
mean: 58.9926 (0.231344)
standard deviation: 24.4216 (0.095771)
kurtosis: 17.5446
skewness: 0.948025
Colors: 4
Histogram:
390: ( 0, 0, 0) #000000 black
10196: ( 67, 57, 0) #433900 srgb(67,57,0)
9770: (111, 79, 37) #6F4F25 srgb(111,79,37)
380: (184,199,111) #B8C76F srgb(184,199,111)
Colormap entries: 16
Colormap:
0: ( 0, 0, 0) #000000 black
1: (255,255,255) #FFFFFF white
2: (104, 55, 43) #68372B srgb(104,55,43)
3: (112,164,178) #70A4B2 srgb(112,164,178)
4: (111, 61,134) #6F3D86 srgb(111,61,134)
5: ( 88,141, 67) #588D43 srgb(88,141,67)
6: ( 53, 40,121) #352879 srgb(53,40,121)
7: (184,199,111) #B8C76F srgb(184,199,111)
8: (111, 79, 37) #6F4F25 srgb(111,79,37)
9: ( 67, 57, 0) #433900 srgb(67,57,0)
10: (154,103, 89) #9A6759 srgb(154,103,89)
11: ( 68, 68, 68) #444444 srgb(68,68,68)
12: (108,108,108) #6C6C6C srgb(108,108,108)
13: (154,210,132) #9AD284 srgb(154,210,132)
14: (108, 94,181) #6C5EB5 srgb(108,94,181)
15: (149,149,149) #959595 srgb(149,149,149)
Rendering intent: Perceptual
Gamma: 0.454545
Chromaticity:
red primary: (0.64,0.33)
green primary: (0.3,0.6)
blue primary: (0.15,0.06)
white point: (0.3127,0.329)
Background color: black
Border color: srgb(223,223,223)
Matte color: grey74
Transparent color: black
Interlace: None
Intensity: Undefined
Compose: Over
Page geometry: 144x144+0+0
Dispose: Undefined
Iterations: 0
Compression: Zip
Orientation: Undefined
Properties:
date:create: 2015-04-10T12:24:18+02:00
date:modify: 2015-04-09T22:33:29+02:00
png:bKGD: chunk was found (see Background color, above)
png:IHDR.bit-depth-orig: 4
png:IHDR.bit_depth: 4
png:IHDR.color-type-orig: 3
png:IHDR.color_type: 3 (Indexed)
png:IHDR.interlace_method: 0 (Not interlaced)
png:IHDR.width,height: 144, 144
png:pHYs: x_res=2835, y_res=2835, units=1
png:PLTE.number_colors: 16
png:sRGB: intent=0 (Perceptual Intent)
signature: 00d9489d55480d588c3329ab0fa844ed2a67eea06fd4dfa793503a36f9c4b160
Artifacts:
filename: level-000.png
verbose: true
Tainted: False
Filesize: 337B
Number pixels: 20.7K
Pixels per second: 0B
User time: 0.000u
Elapsed time: 0:01.000
Version: ImageMagick 6.8.9-8 Q16 x86_64 2014-11-18
第二张照片是scacchiera.png 。
The second pic is "scacchiera.png".
标识为：
Image: scacchiera.png
Format: PNG (Portable Network Graphics)
Mime type: image/png
Class: PseudoClass
Geometry: 144x144+0+0
Resolution: 28.35x28.35
Print size: 5.07937x5.07937
Units: PixelsPerCentimeter
Type: Palette
Endianess: Undefined
Colorspace: sRGB
Depth: 8-bit
Channel depth:
red: 8-bit
green: 8-bit
blue: 8-bit
Channel statistics:
Pixels: 20736
Red:
min: 67 (0.262745)
max: 111 (0.435294)
mean: 89 (0.34902)
standard deviation: 22 (0.0862745)
kurtosis: -2
skewness: -1.18433e-11
Green:
min: 57 (0.223529)
max: 79 (0.309804)
mean: 68 (0.266667)
standard deviation: 11 (0.0431373)
kurtosis: -2
skewness: 7.03683e-11
Blue:
min: 0 (0)
max: 37 (0.145098)
mean: 18.5 (0.072549)
standard deviation: 18.5 (0.072549)
kurtosis: -2
skewness: 0
Image statistics:
Overall:
min: 0 (0)
max: 111 (0.435294)
mean: 58.5 (0.229412)
standard deviation: 17.7694 (0.0696837)
kurtosis: 29.9398
skewness: -1.66976
Colors: 2
Histogram:
10368: ( 67, 57, 0) #433900 srgb(67,57,0)
10368: (111, 79, 37) #6F4F25 srgb(111,79,37)
Colormap entries: 16
Colormap:
0: ( 0, 0, 0) #000000 black
1: (255,255,255) #FFFFFF white
2: (104, 55, 43) #68372B srgb(104,55,43)
3: (112,164,178) #70A4B2 srgb(112,164,178)
4: (111, 61,134) #6F3D86 srgb(111,61,134)
5: ( 88,141, 67) #588D43 srgb(88,141,67)
6: ( 53, 40,121) #352879 srgb(53,40,121)
7: (184,199,111) #B8C76F srgb(184,199,111)
8: (111, 79, 37) #6F4F25 srgb(111,79,37)
9: ( 67, 57, 0) #433900 srgb(67,57,0)
10: (154,103, 89) #9A6759 srgb(154,103,89)
11: ( 68, 68, 68) #444444 srgb(68,68,68)
12: (108,108,108) #6C6C6C srgb(108,108,108)
13: (154,210,132) #9AD284 srgb(154,210,132)
14: (108, 94,181) #6C5EB5 srgb(108,94,181)
15: (149,149,149) #959595 srgb(149,149,149)
Rendering intent: Perceptual
Gamma: 0.454545
Chromaticity:
red primary: (0.64,0.33)
green primary: (0.3,0.6)
blue primary: (0.15,0.06)
white point: (0.3127,0.329)
Background color: white
Border color: srgb(223,223,223)
Matte color: grey74
Transparent color: black
Interlace: None
Intensity: Undefined
Compose: Over
Page geometry: 144x144+0+0
Dispose: Undefined
Iterations: 0
Compression: Zip
Orientation: Undefined
Properties:
date:create: 2015-04-10T20:46:55+02:00
date:modify: 2015-04-10T20:46:55+02:00
png:IHDR.bit-depth-orig: 4
png:IHDR.bit_depth: 4
png:IHDR.color-type-orig: 3
png:IHDR.color_type: 3 (Indexed)
png:IHDR.interlace_method: 0 (Not interlaced)
png:IHDR.width,height: 144, 144
png:pHYs: x_res=2835, y_res=2835, units=1
png:PLTE.number_colors: 16
png:sRGB: intent=0 (Perceptual Intent)
signature: 8a0ca53e6e6f8e8fc4b141c7194b399ed1fc32473b174b6240addbb3f98864e5
Artifacts:
filename: scacchiera.png
verbose: true
Tainted: False
Filesize: 241B
Number pixels: 20.7K
Pixels per second: 0B
User time: 0.000u
Elapsed time: 0:01.000
Version: ImageMagick 6.8.9-8 Q16 x86_64 2014-11-18
如你所见，两张照片都有相同的颜色：
As you can see, both pics have same colors:
Colormap entries: 16
Colormap:
0: ( 0, 0, 0) #000000 black
1: (255,255,255) #FFFFFF white
2: (104, 55, 43) #68372B srgb(104,55,43)
3: (112,164,178) #70A4B2 srgb(112,164,178)
4: (111, 61,134) #6F3D86 srgb(111,61,134)
5: ( 88,141, 67) #588D43 srgb(88,141,67)
6: ( 53, 40,121) #352879 srgb(53,40,121)
7: (184,199,111) #B8C76F srgb(184,199,111)
8: (111, 79, 37) #6F4F25 srgb(111,79,37)
9: ( 67, 57, 0) #433900 srgb(67,57,0)
10: (154,103, 89) #9A6759 srgb(154,103,89)
11: ( 68, 68, 68) #444444 srgb(68,68,68)
12: (108,108,108) #6C6C6C srgb(108,108,108)
13: (154,210,132) #9AD284 srgb(154,210,132)
14: (108, 94,181) #6C5EB5 srgb(108,94,181)
15: (149,149,149) #959595 srgb(149,149,149)
如果我加入他们
convert -page 312x144+0+0 "scacchiera.png" -page +168+0 \
"level-000.png" -background black -layers flatten "joined.png"
然后joined.png图片是：
标识为：
Image: joined.png
Format: PNG (Portable Network Graphics)
Mime type: image/png
Class: PseudoClass
Geometry: 312x144+0+0
Resolution: 28.35x28.35
Print size: 11.0053x5.07937
Units: PixelsPerCentimeter
Type: Palette
Endianess: Undefined
Colorspace: sRGB
Depth: 8-bit
Channel depth:
red: 8-bit
green: 8-bit
blue: 8-bit
Channel statistics:
Pixels: 44928
Red:
min: 0 (0)
max: 184 (0.721569)
mean: 81.9762 (0.321475)
standard deviation: 33.8163 (0.132613)
kurtosis: 0.917842
skewness: -0.743586
Green:
min: 0 (0)
max: 199 (0.780392)
mean: 63.1826 (0.247775)
standard deviation: 25.0478 (0.0982265)
kurtosis: 7.85041
skewness: 0.0804364
Blue:
min: 0 (0)
max: 111 (0.435294)
mean: 17.5233 (0.0687188)
standard deviation: 20.2675 (0.0794802)
kurtosis: 1.51309
skewness: 0.876441
Image statistics:
Overall:
min: 0 (0)
max: 199 (0.780392)
mean: 54.2274 (0.212656)
standard deviation: 26.9673 (0.105754)
kurtosis: 7.87712
skewness: 0.327418
Colors: 4
Histogram:
3846: ( 0, 0, 0) #000000 black
20564: ( 67, 57, 0) #433900 srgb(67,57,0)
20138: (111, 79, 37) #6F4F25 srgb(111,79,37)
380: (184,199,111) #B8C76F srgb(184,199,111)
Colormap entries: 4
Colormap:
0: ( 67, 57, 0) #433900 srgb(67,57,0)
1: (111, 79, 37) #6F4F25 srgb(111,79,37)
2: ( 0, 0, 0) #000000 black
3: (184,199,111) #B8C76F srgb(184,199,111)
Rendering intent: Perceptual
Gamma: 0.45455
Chromaticity:
red primary: (0.64,0.33)
green primary: (0.3,0.6)
blue primary: (0.15,0.06)
white point: (0.3127,0.329)
Background color: black
Border color: srgb(223,223,223)
Matte color: grey74
Transparent color: black
Interlace: None
Intensity: Undefined
Compose: Over
Page geometry: 312x144+0+0
Dispose: Undefined
Iterations: 0
Compression: Zip
Orientation: Undefined
Properties:
date:create: 2015-04-12T15:13:11+02:00
date:modify: 2015-04-12T15:13:11+02:00
png:bKGD: chunk was found (see Background color, above)
png:cHRM: chunk was found (see Chromaticity, above)
png:gAMA: gamma=0.45454544 (See Gamma, above)
png:IHDR.bit-depth-orig: 2
png:IHDR.bit_depth: 2
png:IHDR.color-type-orig: 3
png:IHDR.color_type: 3 (Indexed)
png:IHDR.interlace_method: 0 (Not interlaced)
png:IHDR.width,height: 312, 144
png:pHYs: x_res=2835, y_res=2835, units=1
png:PLTE.number_colors: 4
png:sRGB: intent=0 (Perceptual Intent)
png:text: 2 tEXt/zTXt/iTXt chunks were found
signature: 2049a10c0a2a73f864125d0ba93ccfc604a750667e3ba1d0fe8fe3be38a1cbea
Artifacts:
filename: joined.png
verbose: true
Tainted: False
Filesize: 487B
Number pixels: 44.9K
Pixels per second: 4.493MB
User time: 0.000u
Elapsed time: 0:01.009
Version: ImageMagick 6.8.9-8 Q16 x86_64 2014-11-18
你可以看到调色板是与最初的完全不同。
and you can see that palette is totally different from the initial one.
图片在这里：
- www.dropbox.com/s/jdftk03rizeqcub/scacchiera.png
- www.dropbox。 com / s / 9c1fmav5qni8u2m / level-000.png
- www.dropbox.com/s/8hhd1zyzb31c4me/joined.png
- www.dropbox.com/s/jdftk03rizeqcub/scacchiera.png
- www.dropbox.com/s/9c1fmav5qni8u2m/level-000.png
- www.dropbox.com/s/8hhd1zyzb31c4me/joined.png
问题是： 是否可以使用此调色板：
The question is: is there a way to have ALWAYS this palette:
Colormap entries: 16
Colormap:
0: ( 0, 0, 0) #000000 black
1: (255,255,255) #FFFFFF white
2: (104, 55, 43) #68372B srgb(104,55,43)
3: (112,164,178) #70A4B2 srgb(112,164,178)
4: (111, 61,134) #6F3D86 srgb(111,61,134)
5: ( 88,141, 67) #588D43 srgb(88,141,67)
6: ( 53, 40,121) #352879 srgb(53,40,121)
7: (184,199,111) #B8C76F srgb(184,199,111)
8: (111, 79, 37) #6F4F25 srgb(111,79,37)
9: ( 67, 57, 0) #433900 srgb(67,57,0)
10: (154,103, 89) #9A6759 srgb(154,103,89)
11: ( 68, 68, 68) #444444 srgb(68,68,68)
12: (108,108,108) #6C6C6C srgb(108,108,108)
13: (154,210,132) #9AD284 srgb(154,210,132)
14: (108, 94,181) #6C5EB5 srgb(108,94,181)
15: (149,149,149) #959595 srgb(149,149,149)
这16种颜色的确切顺序是每个重新分配PNG的顺序吗？
exactly with these 16 colors and in this order for each resluting PNG?
推荐答案
我已经为此做了一些工作，相信我可以实现你想要的......基本上，我允许ImageMagick进行重新制作和加入完全按照你的图像，然后我得到ImageMagick以便携式任何地图 PNM 格式输出NetPBM文件。然后我使用我编写的Perl编码器将 PNM 格式文件编码为PNG，以满足您对调色板的特定需求。因此，对于我从 PNM 文件读入的每个真彩色24位RGB像素，我通过做平方误差的总和来计算它最接近的那个调色板条目，并且然后输出一个调色板索引。
I have worked on this some more, and believe I can achieve what you want... basically, I allow ImageMagick to do the repaging and joining of the images exactly as you had it, but then I get ImageMagick to output a NetPBM file in Portable Any Map PNM format. I then encode the PNM format file into a PNG using a Perl encoder I wrote to match your very specific needs as regards the palette. So, for every truecolour 24-bit RGB pixel I read in from the PNM file, I compute which palette entry it is nearest to by doing the sum of the square errors, and then outputting a single palette index.
NetPBM 描述这里。
PNM 格式很容易解析，这就是我选择它的原因。 此处描述了这一点。
The PNM format is really simple to parse and that's why I chose it. It is described here.
所以，你的原始命令几乎是相同的，除了在 stdout 上输出 PNM 文件并读入Perl脚本 pnmtopng 然后生成您想要的 PNG 文件：
So, your original command would be almost identical, except a PNM file is output on stdout and read into the Perl script pnmtopng which then makes the PNG file you wanted:
convert -page 312x144+0+0 scacchiera.png -page +168+0 \
level-000.png -background black -layers flatten pnm:- | ./pnmtopng > out.png
Perl脚本在这里：
The Perl script is here:
#!/usr/bin/perl
use strict;
use warnings;
use Digest::CRC qw(crc32);
use IO::Compress::Deflate qw(deflate $DeflateError) ;
# Our beloved fixed palette
my @palette=(
[0,0,0],
[255,255,255],
[104,55,43],
[112,164,178],
[111,61,134],
[88,141,67],
[53,40,121],
[184,199,111],
[111,79,37],
[67,57,0],
[154,103,89],
[68,68,68],
[108,108,108],
[154,210,132],
[108,94,181],
[149,149,149]
);
################################################################################
# Take chunk of PNG data as parameter, calculate its length & CRC, and output it
################################################################################
sub PNGoutputChunk()
{
my $len=length($_[0])-4;
my $crc = Digest::CRC->new(type=>"crc32");
$crc->add($_[0]);
print pack('N',$len),$_[0],pack('N',$crc->digest);
}
################################################################################
# Main
################################################################################
# Read P6 PNM file from STDIN
my $line = <STDIN>;
chomp($line);
if ($line ne "P6"){die "Expected P6 format PNM file"}
# Read width and height from STDIN
$line = <STDIN>;
my ($width,$height) = ($line =~ /(\d+)\s+(\d+)/);
print STDERR "DEBUG: width=$width, height=$height\n";
# Read MAX PNM value and ignore
$line = <STDIN>;
# Read entire remainder of PNM file
my $expectedsize=$width * $height * 3;
my $PNMdata;
my $bytesRead = read(STDIN,$PNMdata,$expectedsize);
if($bytesRead != $expectedsize){die "Unable to read PNM data"}
# Output PNG header chunk
printf "\x89PNG\x0d\x0a\x1a\x0a";
my $bitdepth=8;
my $colortype=3;
my $compressiontype=0;
my $filtertype=0;
my $interlacetype=0;
# Output PNG IHDR chunk
my $IHDR='IHDR';
$IHDR .= pack 'N',$width;
$IHDR .= pack 'N',$height;
$IHDR .= pack 'c',$bitdepth;
$IHDR .= pack 'c',$colortype;
$IHDR .= pack 'c',$compressiontype;
$IHDR .= pack 'c',$filtertype;
$IHDR .= pack 'c',$interlacetype;
&PNGoutputChunk($IHDR);
# Output PNG PLTE (palette)
my $PLTE='PLTE';
for(my $i=0;$i<scalar @palette;$i++){
$PLTE .= sprintf('%c',$palette[$i][0]); # Red
$PLTE .= sprintf('%c',$palette[$i][1]); # Green
$PLTE .= sprintf('%c',$palette[$i][2]); # Blue
}
&PNGoutputChunk($PLTE);
# Output PNG IDAT chunk
# RFC-1950 zlib compression
my $raw;
# Go through PNM data, and for each RGB pixel, find nearest palette entry
my @PNMvalues = unpack("C*",$PNMdata);
print STDERR "Unpacked ",scalar @PNMvalues," from raw\n";
for(my $pixel=0;$pixel<(scalar @PNMvalues)/3;$pixel++){
# Output filter type byte (0) at start of each scanline
if($pixel%$width==0){$raw .= "\x00";}
my $r=$PNMvalues[(3*$pixel)]; # Red PNM value
my $g=$PNMvalues[(3*$pixel)+1]; # Green PNM value
my $b=$PNMvalues[(3*$pixel)+2]; # Blue PNM value
my $nearest=0;
my $distmin=(255*255)+(255*255)+(255*255); # Couldn't get further
# Go through all palette entries to find nearest to this RGB
for(my $pe=0;$pe<scalar @palette;$pe++){
my $pr=$palette[$pe][0]; # Red palette value
my $pg=$palette[$pe][1]; # Green palette value
my $pb=$palette[$pe][2]; # Blue palette value
my $dist = ($pr-$r)*($pr-$r) + ($pg-$g)*($pg-$g) + ($pb-$b)*($pb-$b);
if($dist<$distmin){
$distmin=$dist;
$nearest=$pe;
}
}
$raw .= sprintf "%c",$nearest;
print STDERR "Pixel: $pixel, r=$r, g=$g, b=$b. Chose palette entry $nearest\n";
}
print STDERR "Length of raw: ",length($raw);
my $deflated;
my $status = deflate \$raw => \$deflated
or die "deflate failed: $DeflateError\n";
my $IDAT="IDAT" . $deflated;
&PNGoutputChunk($IDAT);
# Output PNG IEND chunk
&PNGoutputChunk('IEND');
结果如下：
< img src =https://i.stack.imgur.com/OBO8w.pngalt =在此输入图像说明>
这篇关于加入2个PNG时，ImageMagick会保留自定义调色板的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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![www.dropbox。 com / s / 9c1fmav5qni8u2m / level-000.png](\"http://www.dropbox.com/s/9c1fmav5qni8u2m/level-000.png?dl=0\"){kind=link}
