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Worse image quality after exporting

Posted: Fri Jan 03, 2020 7:44 pm
by Logilink
Hi, I'd like to reduce the size of my document file which consists of many png images. I want it to be all jpgs, so I want to save them first as single files to convert them in other app to jpgs. AFAIK extracting images in PDF-XChange Pro is possible in two ways - by clicking "save image as" manually on every image and saving it in default format or by selecting them all (as image) and exporting automatically all at once in format I want.
The problem I noticed is that exporting degrades their quality (regardless of the format settings) and I can't set the proper (original) resolution of the image. The image is more blurred, this is especially visible in text image. There is no option to export the image with all original parameters. Saving image manually keeps the original quality, but it's manually and too slow for lot of images.
Is this normal or it's a bug and how can I resolve this issue? Or maybe there is some other way to extract images with original quality?

Re: Worse image quality after exporting

Posted: Fri Jan 03, 2020 10:32 pm
by TrackerSupp-Daniel
Hello Logilink,

Currently Saving each image manually is the only way to maintain the original fidelity, exporting takes what is present, rasterizes it, and converts into the desired format, so some loss of quality is possible.

I will bring this up with the Dev team and see if we can offer a "save selected images as" feature, so that you can save the original images In bulk, but at this moment I cannot promise it will be possible.

Kind regards,

Re: Worse image quality after exporting

Posted: Sat Jan 04, 2020 10:24 am
by Logilink
Ok thank you.

Re: Worse image quality after exporting

Posted: Sat Jan 04, 2020 1:39 pm
by Logilink
Btw, do you know how to specify the original format of the image used in pdf? I thought it was png because when I "save image as" there is only png, but it's not the original format right? If I create pdf from jpg there is also only png to save as.

Re: Worse image quality after exporting

Posted: Mon Jan 06, 2020 2:15 pm
by Tracker Supp-Stefan
Hello Logilink,

Once the image is inside the PDF file - it is no longer a .png or .jpg object. It is stored following the PDF specification and it can be 'decoded' back to an image on screen, but the original image format is lost and not available - so we offer PNG as this offers lossless data compression, but the image is created as a new object and it is not like we are e.g. just extracting an existing 'file' from inside the PDF structure.

Regards,
Stefan

Re: Worse image quality after exporting

Posted: Tue Jan 07, 2020 1:16 pm
by Timur Born
PDF Tools can export all images of a PDF file at varying DPI, so I assume that the original resolution/DPI is taken from the image data present in the PDF without resampling. It's like using "Save Image as" on all images of a document.

I do agree that being able to select multiple images for saving within Editor would be useful. That way I would not have to extract all images if I need more than a handful from a PDF.

Re: Worse image quality after exporting

Posted: Tue Jan 07, 2020 11:43 pm
by TrackerSupp-Daniel
Hi Timur,

Thank you for the excellent suggestion! This should help logilink and other users in the meantime, hopefully we can offer a more customizable feature in the future.

Kind regards,