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Converting PDF to PNG produces missing low opacity elements
Posted: 2017-06-07T05:08:29-07:00
by luchin
Hi guys,
I'm trying to convert some PDF pages to PNG images, but some pages with low opacity elements and shapes are not correctly generated.
Here's a jpg of the original page saved with gimp :
https://www.dropbox.com/s/4u1ce6w3lrrh9 ... l.png?dl=0
Trying to convert (adding colorspace since PDF embeds CMYK colorspace) with the following:
Code: Select all
convert -density 400 -colorspace cmyk input_pdf[73] -resize 25% pag73.png
And this is the result:
https://www.dropbox.com/s/7fma247xnsg13 ... d.png?dl=0
- Tried omitting colorspace option and adding CMYK and sRGB profiles, with no luck.
- Tried to edit delegates.xml file with -dUseCIEColor=false, with no difference.
- Tried "-alpha on" option after input file.
Here's an output of
Code: Select all
identify -verbose input_file[73].pdf
Any ideas?
Any help would be appreciated...
Thanks
I'm using ImageMagick 6.8.9-9 Q16 x86_64 2017-05-23 running on Debian Linux 8 (jessie)
Re: Converting PDF to PNG produces missing low opacity elements
Posted: 2017-06-07T05:13:20-07:00
by snibgo
What version of Ghostscript are you using?
Can you post the input PDF?
Does it have transparency? Adobe Reader can show this.
Re: Converting PDF to PNG produces missing low opacity elements
Posted: 2017-06-07T06:00:42-07:00
by luchin
Thank you snibgo,
I'm using gs 9.06
The PDF seems to have transparency, the "show transparency grid" in Adobe reader shows the page objects anchored on a transparent layer.
Unfortunately i can't post the original PDF since it's a technical document not yet published...
Re: Converting PDF to PNG produces missing low opacity elements
Posted: 2017-06-07T06:54:35-07:00
by snibgo
That GS is quite old. I suggest you upgrade it.
Are the objects also semi-transparent?
You might also "+write info:" after reading the PDF, and save to a TIFF so you don't get automatic conversion to sRGB, and "-verbose" to see what command is given to GS:
Code: Select all
convert -verbose -density 400 -colorspace cmyk input_pdf[73] +write info: -resize 25% pag73.tiff
Then you can experiment with "-colorspace sRGB", and/or "-background Blue" before the PDF, etc.
Re: Converting PDF to PNG produces missing low opacity elements
Posted: 2017-06-07T09:47:13-07:00
by luchin
On Debian Jessie that version is the latest available on the stable repositories...
The objects are also semi-transparent.
The output when trying to write tiff file hasn't worked producing an error: (gimp)
"Warning:
The image you are loading has 16 bits per channel. GIMP can only handle 8 bit, so it will be converted for you. Information will be lost because of this conversion.
Unsupported layout, no RGBA loader"
Output to png:
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convert -verbose -density 400 sfogliabile_deformazione_n230_prova.pdf[73] +write info:file.txt -resize 25% immagini/pag73c.png
Code: Select all
"gs" -q -dQUIET -dSAFER -dBATCH -dNOPAUSE -dNOPROMPT -dMaxBitmap=500000000 -dAlignToPixels=0 -dGridFitTT=2 "-sDEVICE=pam" -dTextAlphaBits=4 -dGraphicsAlphaBits=4 "-r400x400" -dUseCIEColor -dFirstPage=74 -dLastPage=74 "-sOutputFile=/tmp/magick-18046z7LVyQGljIpF%d" -dUseCIEColor=false "-f/tmp/magick-18046D37Fuu7jH8JV" "-f/tmp/magick-18046Xp3TQRIBFE4b"
/tmp/magick-18046z7LVyQGljIpF1 PAM 3783x4649 3783x4649+0+0 8-bit ColorSeparation CMYK 70.35MB 0.140u 0:00.140
sfogliabile_deformazione_n230_prova.pdf[73]=>sfogliabile_deformazione_n230_prova.pdf[73] PAM 3783x4649 3783x4649+0+0 16-bit ColorSeparation CMYK 0.000u 0:00.000
sfogliabile_deformazione_n230_prova.pdf[73]=>immagini/pag73c.png[73] PAM 3783x4649=>946x1162 946x1162+0+0 16-bit sRGB 2.046MB 4.150u 0:01.350
link to info.txt:
https://www.dropbox.com/s/96plk21mc8wc2rm/file.txt?dl=0
Changing to "background blue" and "colorspace srgb" didn't produce any differences...
Re: Converting PDF to PNG produces missing low opacity elements
Posted: 2017-06-08T09:30:03-07:00
by luchin
Edit: Updated to Gs 9.21 by compiling it from source. Now the output graphics is correct.
Thank you for support
