Enhance Scanned Pages - Image upscale

[Loki@99]

Hi,

It's a feature request.

Feature description
Add an option to upscale images in Enhance Scanned Pages which uses Waifu2x processing.

Issue
The following file scan resolution is a bit low.

File_low resolution.pdf

(3.05 MiB) Downloaded 89 times

I tried to increase its readability with PDFXCE Enhance Scanned Pages > Text Sharpening but results weren't great.
Moreover, it can't handle other images on the page very well.

PDFXCE Results
Enhance Scanned Pages - Text Sharpening : Low

After some research, I found a way to get pretty good results with the following website powered by an open-source project.
https://waifu2x.booru.pics/ (website is closed now)
https://www.waifu2x.net/


It's specialized for comics and manga so it handles text and images very well.

Below a before and after Waifu2x processing.

Original file

Waifu2x - Noise reduction High - Scale 2X - Style Photo

Maybe the result isn't really obvious on above screenshots so I added results on page two of the file sample.
There is a clear difference when you zoom.

Bellow some useful links

• https://github.com/nagadomi/waifu2x

• https://github.com/YukihoAA/waifu2x_snowshell. A GUI for Waifu2x

Thanks for considering this,

[Stefan - PDF-XChange]

Hello Loki@99,

While I cant make any promises - I will ask our devs working on this tool to take a look at your suggestion!

Kind regards,
Stefan

[David.P]

Hello all,

I like and support Loki's feature request.

Once the Devs are going to look into it, this related feature request could also be considered.

The suggestion over there is about improving scanned documents—such as those scanned in color or grayscale—when converting them to black and white. The idea is to first increase the original resolution, for example by doubling it, before performing the black-and-white conversion. This would help minimize the loss of detail, particularly sharpness, for example in scanned text or drawings:

A use case for me is as follows. I often have (scanned) PDF files in e.g. 300 dpi grayscale (or color). But I normally need these [files] in pure black and white. If I simply convert the images directly to black and white, part of the image information, or optical resolution, of the original image is lost. The black and white images then become rather pixelated.

Therefore, it would be useful to, for example, double the resolution of the grayscale images (using "Recompress Images") to 600 dpi first, and then to generate 600 dpi black-and-white images from the upsampled images. When the black-and-white images are then compressed using JBIG, for example, the file size of these high-resolution black-and-white images is still tiny and negligible.

Click image to view animation

Thank you for looking into this.

Best regards
David

[Stefan - PDF-XChange]

Hello David.P,

Thanks for adding your voice.
The developer who will look into this topic will come to his office in about 3 hours - so he will also see your feedback directly when reading the above discussion.

Kind regards,
Stefan

[Loki@99]

Hi,

Any update on this ?

[Stefan - PDF-XChange]

Hello Loki@99,

I will ask my colleagues once again.

Kind regards,
Stefan