PDF to JPG causes black background

[virtual]

I have a PDF that was created with Adobe Illustrator CS4 and has a transparent background. Unfortunately I cannot post the PDF here as I do not have permission, but I have tried, what seems to be, everything under the sun to make it a white background.

I have tried the following commands
-alpha off
-background white
-flatten

So my command looks like:

Code: Select all

exec("convert -alpha off input.pdf -resize 500x700! -background white -flatten -quality 90 output.jpg");

However it still has a black background. Is there any way that these would not work on PDF's made with Adode Illustrator CS4 with transparent backgrounds?

Thanks for your help!

[snibgo]

This seems to be a common problem. Try searching this forum for "pdf transparent", eg
viewtopic.php?f=1&t=15985&p=57607&hilit ... ent#p57607

[virtual]

Aha. It was a CMYK color document. Thanks, all fixed.