Thumbnail generated from CMYK tiff loses profile info as well as colors

[ashokpanghal]

We have couple of tiff and eps images with CMYK colorspace or embedded icc profile ISO39 U320 K90. We are using below command and its other variants (using -profile <profile.icc>) but none seems successful in generating correct png thumbnails which retains both colors as well as profile .

Code: Select all

convert.exe -density 1200 -colorspace CMYK ${file} -write mpr:image +delete ( mpr:image -thumbnail "1280x1280>"  -write cq5dam.thumbnail.1280.1280.png ) null:

Here are some sample images : https://www.dropbox.com/s/gfmy3kaiw0hop1e/cd.tif?dl=0

Please let us know if there are options to retain colorspace profile while generating thumbnails

[snibgo]

PNG file can store RGB only. They cannot store CMYK. If you want PNG, I suggest you convert to sRGB, using "-profile sRGB.icc" or similar.

[ashokpanghal]

Hey snibgo, Thanks for the clarification on storing part of CMYK profile in png. But png thumbnail should not loose color, it should maintain the fidelity of colors and contrasts while converting from CMYK to RGB .

[snibgo]

Yes, and it will if you convert to sRGB using "-profile sRGB.icc" or similar.

[ashokpanghal]

I used sRGB_IEC61966-2-1_black_scaled.icc ( hope thats what you meant). Here is the command used with attached sample image

convert.exe -density 1200 cd.tif -write mpr:image +delete ( mpr:image -thumbnail "1280x1280>" -profile "sRGB_IEC61966-2-1_black_scaled.icc" -write cq5dam.thumbnail.1280.1280.png ) null

This generated png with dim colors and contrast. is that expected to loose this much detailing?

can you try this command and suggest something for improved output thumbnail.

[snibgo]

The result I get from sRGB.icc is slightly different, I guess because it doesn't have the XYZ black point scaled to zero.

I don't know which version is more accurate for your file.

How do you know "This generated png with dim colors and contrast"? What are you comparing it to? I suppose you are comparing it to cd.tif, using the same software to convert them both to the profile of your RGB monitor? What software?