pdf output can be compressed in different ways. Newer versions of ImageMagick seem to reraster the image instead of just embedding the original jpg, and then output it without compression. Try to use compression method jpeg for the output and quality level 75%

As you say, your images are line drawings, you may also prefer to reduce number of colors to 2 (black and white) and then save them using some lossless compression scheme instead (LZW etc) instead of jpeg

Maybe you also would like to switch to graphicsmagick instead, (also provides Perl bindings) the default settings of which I generally prefer (in particular w.r.t. filesize, without visibly compromising quality)

In reply to Re: Size problem of pdf file using ImageMagick by jf1
in thread Size problem of pdf file using ImageMagick by merrymonk

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