graphicsmagick - convert images to pdf and vice versa

Question

I want to shift from imagemagick to graphicsmagick

But I encounter some issues with the syntax

With imagemagick

First I need to merge some images into a PDF

convert -density 300 page_*.tif output.pdf

And then I need to create a thumbnail of the first page of the PDF

convert -density 300 file.pdf[0] -background white -alpha remove -resize 140x140 -strip -quality 40 thumb.jpg[0]

This works fine.. But I want to switch the first command to graphicsmagick

The graphicsmagick syntax here works fine

gm convert -density 300 page_*.tif output.pdf

But when creating the thumbnail with imagemagick the output has the right size but the acutal image is downsized inside the image itself?!

That's likely what a 140x140 image looks like at 300dpi in your output PDF. Can graphicsmagick take a size argument for the resulting file? That may be worth looking into — Pekka, Nov 26 '15 at 18:30
Compare the two thumnails.. There is a significant difference.. The graphics version is downsized inside the image itself — clarkk, Nov 26 '15 at 18:32
What size is the resulting PDF in each case? (Physical dimensions) — Pekka, Nov 26 '15 at 18:32
The PDFs look the same for me? And Acrobat says they are the same size — Pekka, Nov 26 '15 at 18:35

score 4 · Answer 1 · answered Apr 04 '18 at 07:25

You need to change your convert command into:

convert -density 300 -define "pdf:use-cropbox=true" file.pdf[0] -background white -alpha remove -resize 140x140 -strip -quality 40 thumb.jpg[0]

And perhaps add a -resize "2000x2000>" to limit the size of the resulting JPEG, especially with high density values.