JPG files are too small when converted from PDF with imagemagick

Question

I'm on Ubuntu 10.04 with imagemagick. I used this command:

convert myfile.pdf -density 300 file.jpg

This works well, but the JPGs are only about an inch high. How can I preserve the paper size in the conversion process?

Answer 1

You can set the -density before you read the source pdf, so you can do

convert -density 300 myfile.pdf myfile.jpg

and it'll read the pdf at 300dpi, then render out the jpg at the original size of the pdf, whatever that was.

Answer 2

I don't know if Imagemagick can sense the correct height automatically. However if you can come up with the correct height in pixel you can set the height manually.

According to http://www.indigorose.com/forums/archive/index.php/t-13334.html an A4 paper has the height of 3508 pixels in 300 dpi so then you can do

convert myfile.pdf -density 300 -geometry x3508 file2.jpg

This command sets the width to 3508 pixels and preserves aspect radio. See http://www.imagemagick.org/script/command-line-processing.php#geometry for details on the -geometry argument.