Once you have obtained a PDF file consisting of pages, you need to convert each page to a PNG (for example) using
convert command provided by ImageMagick.
The syntax is as follows:
convert -density <number> -alpha <option> "filename.pdf" "filename-%03d.png"
<number> is any positive integer. The larger it is the bigger in size the produced image. It depends on the size you want to get. In my experience, you can choose between 100 to 300 or even more. Please make a trial and error test.
<option> is one of
on (transparency enabled),
off (transparency disabled), or
remove (transparency removed). Actually I only use either
%03d is used to append a zero-leading-3-digit counting number for each image. If three digit is too greedy, you can change to two!
- Quotes can be removed if your
filename has no spaces.
For example you invoke as follows,
convert -density 100 -alpha on "filename.pdf" "filename-%02d.png"
For more detailed explanation, see my another related answer here.