convert multipage PDF to high-resolution animated gif

[matzke]

Hi all,

I have made some progress on this question via google, but I have gotten stuck.

My goal is to convert a multipage PDF file into an animated gif.

I have done this successfully with:

convert -delay 20 stochastic_maps_DEC_vs_DECj_M3_v1_WORKED_ARCHIVE_yes_dotted_lines.pdf stochastic_maps_DEC_vs_DECj_M3_v1_WORKED_ARCHIVE_yes_dotted_lines.gif

...however, the images (which are 12" wide x 6" tall in the PDF, and looks good as a vector image in the PDF) come out blurry under this command, and also the image displays in a browser as rather small (perhaps 6" wide, yes I clicked the zoom option to make sure it wasn't some preview).

In an attempt to produce a bigger, and higher resolution, image, I tried:

convert -delay 20 -extent 1200x600 stochastic_maps_DEC_vs_DECj_M3_v1_WORKED_ARCHIVE_yes_dotted_lines.pdf stochastic_maps_DEC_vs_DECj_M3_v1_WORKED_ARCHIVE_yes_dotted_lines_larger.gif

...this improved the resolution nicely, but the image display size is the same.

I then tried various combinations of "-resize" and "-extent", but it appears that I can only increase the size, or the resolution, but not both. E.g.:

convert -delay 20 -background white -resize '150%' -extent '3200x1600<' -background white stochastic_maps_DEC_vs_DECj_M3_v1_WORKED_ARCHIVE_yes_dotted_lines.pdf stochastic_maps_DEC_vs_DECj_M3_v1_WORKED_ARCHIVE_yes_dotted_lines_larger5.gif

...the image is now a good size, but still blurry. Higher values for -extent produce "malloc" errors. I would try troubleshooting these, maybe there is a way to increase memory, but I'm not even sure I'm "doing it right" to start.


UPDATE: Actually, this is (almost) the right size and resolution:

convert -delay 20 -background white -resize '150%' -density 144x144 -background white stochastic_maps_DEC_vs_DECj_M3_v1_WORKED_ARCHIVE_yes_dotted_lines.pdf stochastic_maps_DEC_vs_DECj_M3_v1_WORKED_ARCHIVE_yes_dotted_lines_larger6.gif

...however, now I am getting an issue where it looks like many of the gifs in the animation are writing on top of each other, rather than completely clearing the previous image and writing a new one, which is what I want. Strangely, I only saw this sometimes in the previous runs, and I can't find a pattern to which commands are causing this problem.

Any help very much appreciated here or via email! Cheers!

Nick
matzke@nimbios.org

[snibgo]

... come out blurry under this command, and also the image displays in a browser as rather small ...

The cure is probably "-density X" before reading the PDF, where X is a suitable number. I suggest you get this correct, and don't do "-resize" or "-extent".

... many of the gifs in the animation are writing on top of each other ...

The cure may be "-layers coalesce" before writing the GIF, but I'm not an animation expert.

[matzke]

Thanks! The tip about -density being all that was needed helped.

The images-overwriting-each-other problem was solved with -dispose. So, this command does everything I wanted to convert a multipage PDF to a nice big high-resolution animated gif:

# -dispose option should help
# http://www.alecjacobson.com/weblog/?p=2601

convert -delay 20 -density 200x200 -dispose previous stochastic_maps_DEC_vs_DECj_M3_v1_WORKED_ARCHIVE_yes_dotted_lines.pdf -layers coalesce stochastic_maps_DEC_vs_DECj_M3_v1_WORKED_ARCHIVE_yes_dotted_lines_larger7.gif

Thanks!!!!!!
Nick

[fmw42]

You might try the following. It might make the gif animation smaller

convert -delay 20 -density 200x200 -dispose previous stochastic_maps_DEC_vs_DECj_M3_v1_WORKED_ARCHIVE_yes_dotted_lines.pdf -coalesce -layers optimize stochastic_maps_DEC_vs_DECj_M3_v1_WORKED_ARCHIVE_yes_dotted_lines_larger7.gif

You might also want to add -loop X, where X=0 is loop forever

Note here it is just -coalesce and not -layers coalesce

[snibgo]

I should add (before Fred does) that using "-resize" after "-density" can be useful, eg using "-density" twice as large as needed then "-resize 50%". This is known as supersampling. However, I think it's best to find the correct "-density" first, then supersample if needed.

[matzke]

Thanks for the suggestions! I tried:

convert -delay 20 -density 100x100 -dispose previous stochastic_maps_DEC_vs_DECj_M3_v1_WORKED_ARCHIVE_yes_dotted_lines.pdf -coalesce -layers optimize stochastic_maps_DEC_vs_DECj_M3_v1_WORKED_ARCHIVE_yes_dotted_lines_100dpi_optimized.gif

...the result is a filesize 4 times smaller, but it looks kind of screwy:

http://phylo.wdfiles.com/local--files/b ... imized.gif


If anyone's interested, here are the animated GIFs that look good:

http://phylo.wikidot.com/biogeobears#toc0

Cheers!
Nick

[fmw42]

try changing or removing the dispose method. or try -layers coalesce -layers optimize

see http://www.imagemagick.org/Usage/anim_basics/#dispose

if all fails to help, you can post your pdf to dropbox.com (public folder) and post the url here.

[matzke]

I've tried several variants with -layers optimize, -previous, etc., but I can't get something that looks good. Making a smaller file size is not very important in my case, I'm quite happy with what this produced:

convert -delay 20 -density 200x200 -dispose previous stochastic_maps_DEC_vs_DECj_M3_v1_WORKED_ARCHIVE_yes_dotted_lines.pdf -layers coalesce stochastic_maps_DEC_vs_DECj_M3_v1_WORKED_ARCHIVE_yes_dotted_lines_larger7.gif

Which is here:

http://phylo.wikidot.com/biogeobears#toc0

Thanks for your help! Cheers, Nick