To create image thumbnails from a PDF document, run this in a terminal window:
$ convert -thumbnail x300 -background white -alpha remove input_file.pdf[0] output_thumbnail.pngThe parameters to convert do the following things:
| Parameter | Effect |
|---|---|
-thumbnail | Similar to -resize, but optimized for speed and strips metadata. |
x300 | Make the thumbnail 300px tall, and whatever width maintains the aspect ratio. |
-background white | Sets the thumbnail background to white. |
-alpha remove | Removes the alpha channel from the thumbnail output. |
input_file.pdf | The PDF file to use as input. |
[0] | The page number of the input file to use for the thumbnail. |
output_thumbnail.png | The output thumbnail file to create. |
If you want larger thumbnails, just change the x300 parameter to match. If you want to output .jpg’s (or anything else, like .gif), just change the file extension on the output_thumbnail.png parameter. If you leave the [0] off the end of the input filename, you’ll get a thumbnail for each page, not just the first; setting it to [1] will get you a thumbnail of the second page, and so on…
Do a whole folder at a time
To create thumbnails for a whole folder of PDF’s, do this:
$ for f in *.pdf; do convert -thumbnail x300 -background white -alpha remove "$f"[0] "${f%.pdf}.png"; doneThis will create thumbnails with filenames that match the input PDF’s, except with an extra .pdf extension.
Requirements
This requires ImageMagick and Ghostscript, which you can install like this:
$ sudo apt-get install imagemagick ghostscriptThis technique should also work on a Mac, provided you have these both installed.