[SOLVED] Why the size of file with cropped image is the same as of initial one?

Why the size of file with cropped image is the same as of initial one?

I have scanned my copybook and want to crop out extra white regions with Inkscape.

To achieve this, I import initial image (PDF) to Inkscape, draw appropriate rectangle, and use Object->Clip->Set to cut out needed region. Then I resize page to drawing and save obtained page as new PDF file through File->Save a Copy.

I expected that the size of the new PDF file (with cropped image) will be less than the size of the initial PDF (with image without crop), but they are the same.

What is the reason of this and may it be worked around?

I use Inkscape 0.91 at Linux Mint 18.2.

Thank you in advance.

Solution

Because the original image is still there, fully intact and with all its contents. The cropping rectangle are just instructions to the PDF viewer to crop out those regions when rendering the image.

However in Inkscape you can bake the crop rectangles and when exporting to PDF "apply raster effects" which should actually alter the contained image(s).