[scribus] FULL TEXT of: Cropping invisible image areas on PDF export
dan.btown at hotmail.de
Tue Feb 2 20:12:24 CET 2010
>> is there a way to crop image data that lies outside
>> the scribus image frames on export to PDF?
>> When I inspected Scribus-made PDFs I realized that
>> the images are exported to PDF in total although areas
>> of the images may be covered (that is, "behind") other
>> images or outside the image frame because of it being
>> smaller than the contained image.
>> I'm not sure if the scripts for web-optimising Scribus
>> PDFs handle this task -- or do they?
> If you flatten the file then layers and overlays
> are compressed into a single image. The easiest
> way to flatten a document is to export if as pdf
> 1.4 or higher. Then import it into Acrobat Reader
> and print to file. Then run that print file through
> Ghostscript script:
> ps2pdf13 filename.ps
> The end result will have all the layers, overlays
> and transparencies etc. flattened and the pdf will
> be much smaller in most cases.
> John Culleton
We'll give this a try next time.
> This is why we recommend using an image editor to crop images,
> especially when the part you use is a small fraction of the image, and
> there are a lot of images.
> If you need to keep the original, just work with a cropped copy.
You know, we always thought yours were a little lier, trying to
force us into using image editors for no good reason.
To be a little more searious, there are times when all the good
reasons to use the image editor beforehand, no matter how well
thought out, are not of the essence.
This is valid, for example, when one wants to publish the layout
as screen print (where you usually want to keep some additional
image outside the frame but in the PDF in order for the printer
workshop to compensate for snapp-off distortion) on the one hand
and to publish the same layout as a PDF for monitor use, where
the additional "hidden" image areas will simply blow file size.
Moreover, with the task at hand, the problem was that we had image
files from scanned cardboard with historic fabric specimens glued to
the board that the typical PDF user would view with an enlargement of
around 400 to 800 % (!) where 96 dpi for monitor use is simply not
enough, while other regions of the cardboard image would perfectly
suffice with a resolution of around 150 dpi.
Our first approach was to have the same image with different
resolutions and overlay the low-res image in parts with the hi-res
image areas (showing the specimens) within Scribus.
However, since there was no simple approach to crop away the
"hidden" image areas on PDF export from Scribus, we finally took
a different approach to reduce PDF file size and worked with the
hi-res images only, but reducing the contained information
(or "high-frequency image areas") outside the image regions
displaying the fabric specimens by applying gaussion blur and
pixelizing to 4x4 pixel tiles (yes, in the image editor).
This removed enough information from the hi-res images to allow
for a halfway good JPEG compression within the Scribus gene-
Cheers anyways --
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