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resolution, size when extracting from pdf vs the gimp

Posted: 2015-07-06T23:50:05-07:00
by reiisi
I have a pdf of scanned images, theoretically jpeg images.

ImageMagick's identify -verbose tells me the same are 1032x728 at 72 dpi. If I use ImageMagick's convert to extract them, that's how they end up.

The gimp, on the other hand, will offer me a selection dialog, from which it will import them individually as 1304x932 at 100 px/in.

Either way is odd, because I selected 300dpi at scan time. But, then, 22Mb for 36 images is not 13" x 9" at 300 dpi, unless heavily compressed.

Anyone have an idea what's happening?

Joel Rees

Re: resolution, size when extracting from pdf vs the gimp

Posted: 2015-07-07T02:32:33-07:00
by snibgo
ImageMagick tries to make an image from each page of the PDF. "1032x728 at 72 dpi" is information about the page. However, in your case, each page probably contains a single raster image, with different metadata. In such cases, I prefer to extract the images with pdfimages, and manipulate the results with IM.

Perhaps Gimp is extracting the images. IM (sadly) doesn't do that.