Photoshop see negative

[taratata]

Now I solved the negative issue: it is caused by jpeg compression not correctly understood by photoshop. I jpeg compress with Callas pdfToolbox and photoshop is giving me a positive image now.
I will later drop images compressed by pdfToolbox and photoshop for you to compare with IM

[taratata]

here: https://www.dropbox.com/s/6f2x8ramaxcvr ... e.zip?dl=0

[taratata]

I solved the negative issue, photoshop does not understand IM jpeg compression. I used zip with

Code: Select all

magick in.jpg  -density 300 -channel cmyk +compress -alpha transparent -clip -alpha opaque +clip -trim +repage -strip -compress zip result.pdf

here file post treated by IM then compressed by callas pdftoolbox and fully computed by photoshop for you to compare : https://www.dropbox.com/s/6f2x8ramaxcvr ... e.zip?dl=0

[taratata]

also the original jpg https://www.dropbox.com/s/q0lokpco3cous ... 0.jpg?dl=0

[fmw42]

Imagemagick uses libjpeg, unless you have installed some other jpg delegate. So the fault would be with libjpeg

[taratata]

Alright. I am no developper and I am not able to report this to libjpeg maintainers, nor I could speak the same language or do testing. Will you find an interest in checking that with them ?

[fmw42]

That is up to the Imagemagick developers. They would have to research this issue on the Imagemagick side first.

[taratata]

ok, how to heads up IM devs ?

[fmw42]

I have checked your information. Indeed, if the input is CMYK JPG, then the PDF is saved as JPG and PS will not correct the color inversion. But if -compress zip or -compress none is supplied, then PS opens it properly.

Negated in PS:

Code: Select all

convert in.jpg -density 300 -alpha transparent -clip -alpha opaque +clip -trim +repage out1.pdf

Shows properly in PS:

Code: Select all

convert in.jpg -density 300 -alpha transparent -clip -alpha opaque +clip -trim +repage -compress zip out2.pdf

convert in.jpg -density 300 -alpha transparent -clip -alpha opaque +clip -trim +repage -compress none out3.pdf

The Imagemagick developers will need to check this and see if it is an Imagemagick issue, a libjpeg issue or a Photoshop issue.

Oddly, adding -compress zip or -compress none and saving as JPG works fine. IM reports it still as a JPG compressed JPG file.

I do not know how Imagemagick or libjpeg handles this non-jpeg compression.