Split iamge in its CMYK colour and rejoin

[myspacee]

Hello to all,
BIG problem here in production.

We print newspaper.

Our process generate pages image, split it in 4 different CMYK colour (black - yellow - magenta - ciano)
toobtain plates for printing.

Now, user must control if result is ok, but often 'forgot' this important step (program sometime go in error)

My question:
is possible to join [black - yellow - magenta - ciano] images to obtain original one?

thank you for any help,

m.

[fmw42]

Yes, see

http://www.imagemagick.org/Usage/channels/#separate
and
http://www.imagemagick.org/Usage/channe ... bine_other

[myspacee]

reading now not finish yet but try this:

convert cyan.jpg magenta.jpg yellow.jpg black.jpg -set colorspace CMYK -combine -colorspace CMYK CMYK_combined.jpg

but black is skipped.

reading better :
The last example will not work for 'CMYK' images, as the 'Black' channel image does not actually contain a black channel! As such "-compose CopyBlack" will fail to find valid data to copy. I regarded this as a bug, but is currently unlikely to be fixed.

anyone can confirm that bug ?

anyone can join 4 CMYK in a single image ?

thank you,
m.

[fmw42]

reading now not finish yet but try this:

convert cyan.jpg magenta.jpg yellow.jpg black.jpg -set colorspace CMYK -combine -colorspace CMYK CMYK_combined.jpg

but black is skipped.

reading better :
The last example will not work for 'CMYK' images, as the 'Black' channel image does not actually contain a black channel! As such "-compose CopyBlack" will fail to find valid data to copy. I regarded this as a bug, but is currently unlikely to be fixed.

anyone can confirm that bug ?

anyone can join 4 CMYK in a single image ?

thank you,
m.

IM 6.4.7-6 Q 16 Mac OSX Tiger

This works for me as psd:

convert rose: -colorspace CMYK -separate rose_cmyk.jpg

convert rose_cmyk-0.jpg rose_cmyk-1.jpg rose_cmyk-2.jpg rose_cmyk-3.jpg -set colorspace CMYK -combine rose_cmyk_combined.psd

identify -verbose rose_cmyk_combined.psd
Image: rose_cmyk_combined.psd
Format: PSD (Adobe Photoshop bitmap)
Class: DirectClass
Geometry: 70x46+0+0
Resolution: 72x72
Print size: 0.972222x0.638889
Units: Undefined
Type: ColorSeparation
Endianess: Undefined
Colorspace: CMYK
Depth: 8-bit
Channel depth:
cyan: 8-bit
magenta: 8-bit
yellow: 8-bit
black: 8-bit
Channel statistics:
cyan:
min: 0 (0)
max: 119 (0.466667)
mean: 11.8292 (0.046389)
standard deviation: 23.5841 (0.0924868)
magenta:
min: 0 (0)
max: 237 (0.929412)
mean: 84.0587 (0.329642)
standard deviation: 77.7648 (0.30496)
yellow:
min: 0 (0)
max: 218 (0.854902)
mean: 106.092 (0.416046)
standard deviation: 69.7423 (0.273499)
black:
min: 0 (0)
max: 217 (0.85098)
mean: 103.048 (0.404109)
standard deviation: 68.3539 (0.268055)


This works as jpg

convert rose_cmyk-0.jpg rose_cmyk-1.jpg rose_cmyk-2.jpg rose_cmyk-3.jpg -set colorspace CMYK -combine rose_cmyk_combined.jpg

identify -verbose rose_cmyk.jpg
Image: rose_cmyk.jpg
Format: JPEG (Joint Photographic Experts Group JFIF format)
Class: DirectClass
Geometry: 70x46+0+0
Resolution: 72x72
Print size: 0.972222x0.638889
Units: PixelsPerInch
Type: ColorSeparation
Endianess: Undefined
Colorspace: CMYK
Depth: 8-bit
Channel depth:
cyan: 8-bit
magenta: 8-bit
yellow: 8-bit
black: 8-bit
Channel statistics:
cyan:
min: 0 (0)
max: 119 (0.466667)
mean: 11.8292 (0.046389)
standard deviation: 23.5798 (0.0924697)
magenta:
min: 0 (0)
max: 235 (0.921569)
mean: 84.0755 (0.329708)
standard deviation: 77.7871 (0.305047)
yellow:
min: 0 (0)
max: 219 (0.858824)
mean: 106.111 (0.416121)
standard deviation: 69.744 (0.273506)
black:
min: 0 (0)
max: 218 (0.854902)
mean: 103.025 (0.404021)
standard deviation: 68.3662 (0.268103)

[myspacee]

ok upgrade imagemagick and obtain better result.

lost a bit of time to understand that IM works with negative images...

Mine images are not negative, anyone can post some code to negative given image ?

thank you,
m.

[fmw42]

ok upgrade imagemagick and obtain better result.

lost a bit of time to understand that IM works with negative images...

Mine images are not negative, anyone can post some code to negative given image ?

thank you,
m.

convert image.jpg -negate image_negative.jpg

see -negate

http://www.imagemagick.org/script/comma ... ptions.php