Q: Is PDFNet SDK (http://www.pdftron.com/pdfnet) able to resize pages
or downscale (reduce DPI of images ) a pdf file ? Does it keeps all
the rest information of the document intact ?
A: Just to clarify, do you need to reduce the size of all images or
you need to resize PDF pages? Both can be done with PDFNet SDK, but
you may need to use different APIs.
In case you need to resale the entire page you can use
page.Scale(fract). Another approach is to place an existing the page
on a blank new page and set a transformation matrix on the resulting
form xobject (http://groups.google.com/group/pdfnet-sdk/browse_thread/
thread/23e00e42023cd562/10130910b0d3eabb).
If case you need to change the resolution of existing images in a PDF
document (e.g. to optimize PDF) you can use the approach described in
the following articles:
http://groups.google.com/group/pdfnet-sdk/browse_thread/thread/5b50d2c842347087/36c619d76e56c23f
http://groups.google.com/group/pdfnet-sdk/browse_thread/thread/6950ce1219ae1faf/3d65a89632b42c4f
http://groups.google.com/group/pdfnet-sdk/browse_thread/thread/a16940d74b8339d9/e1c58320a8143683
As an example of different appraches used to enumerate all images in a
PDF document you may also want to take a look at ImageExtract and
JBIG2 samples: