convert pdf to image format or viceversa

convert pdf to png(image) file:

pdftoppm -rx 300 -ry 300 -png file.pdf prefix

source:
http://askubuntu.com/questions/50170/how-to-convert-pdf-to-image/50180


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To convert image(s) to pdf use:

convert Image1.jpg Image2.jpg  myfile.pdf

So, myfile.pdf will contain both the image files in pdf format.

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Also, to reduce the size of the image by 50%

convert  -resize 50% source.jpg  destination.jpg

Note: it can be png format too.

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