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Re: Photoshop see negative
Posted: 2019-07-17T03:58:00-07:00
by 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
Re: Photoshop see negative
Posted: 2019-07-17T06:02:25-07:00
by taratata
Re: Photoshop see negative
Posted: 2019-07-17T06:05:44-07:00
by 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
Re: Photoshop see negative
Posted: 2019-07-17T06:06:58-07:00
by taratata
Re: Photoshop see negative
Posted: 2019-07-17T08:30:25-07:00
by fmw42
Imagemagick uses libjpeg, unless you have installed some other jpg delegate. So the fault would be with libjpeg
Re: Photoshop see negative
Posted: 2019-07-17T08:53:25-07:00
by 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 ?
Re: Photoshop see negative
Posted: 2019-07-17T08:57:06-07:00
by fmw42
That is up to the Imagemagick developers. They would have to research this issue on the Imagemagick side first.
Re: Photoshop see negative
Posted: 2019-07-17T08:59:06-07:00
by taratata
ok, how to heads up IM devs ?
Re: Photoshop see negative
Posted: 2019-07-17T09:23:14-07:00
by 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.
