On approximately 9/2/2009 11:26 AM, came the following characters from
the keyboard of Tyson Boellstorff:
> Running ghostscript for windows 8.64, ImageMagick 6.4.9 Q16
>
> I have a number of scanners to support that throw their images into pdf files
> as streams. I'd like to convert them into tiff images. The resolution of the
> pdf 'envelope' is 72x72, appropriate for display on screen. The resolution of
> the scan can be anything from that to 1200x1200 (or greater). However, when I
> run convert or when I use Image::Magick to write the image out as a
> multi-page tiff, the resolution of each image is now 72x72. Not good. This
> also fails for conversion to png format.
>
> I can manually run gsview and display/print the pdf at the 200x200 resolution
> with no problems.
>
> When I run
> @Attribs=qw(width height x-resolution y-resolution);
> $image=Image::Magick->new();
> $image->read('test.pdf');
> and loop through all the pages using this:
> @attribvals=$image->[$i]->Get(@Attribs);
>
> @attribvals shows that the resolution is 72x72, and width and height compute
> out to scan size for each page.
>
> I can hard code these values to a better resolution, but more appropriately,
> I
> should be getting the resolution from the stream itself. Since Get() only
> returns the 'envelope' size, how would a person get this information?
Apparently the only way to do it at the moment, is mark down the actual
scan resolution, and allow a parameter when running convert or
Image::Magick.
I researched this about and found nothing free, and then asked about
this here and was told that while it is straightforward with commercial
software to obtain this information, that no known free package provides it.
Personally, I do my scans with IrfanView, and save as multi-page TIFF
rather than PDF, which saves a step in my process, so I only have to
convert those that are sent by other people that scan to PDF, and they
don't tell me the scan resolution, so I always have to experiment or
guess. Fortunately, those occasions are few.
I don't know if you can convince your scanners (people, machines,
software) to use IrfanView and save as multipage TIFF, but maybe that is
worth investigating.
Good luck, and if you are more successful than I at finding a free
package, be sure to report back here.
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