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What are the best ImageMagick parameters to upscale an image that contains text in Latin alphabet?

Take this image as example: enter image description here

I did some experimenting, for example: magick convert in.png -filter lanczos -resize 400% -unsharp 0x1 out.png

But in the resulting image the text is not of the same color, there are shades of gray:

enter image description here

My original image is grayscale (not black and white), but that seemed to change the color of the original text and made it blurry.

robertspierre
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1 Answers1

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Resizing a raster image will always produce some kind of blur, large scale factors will show it clearly.

To understand this fact and many others with digital image conversions and related issues; please do read up on the basics, presented freely here:
https://www.cambridgeincolour.com/learn-photography-concepts.htm
("Understanding Sharpness" the most suiting subject here, but understanding it all will help)

But then:
https://appimage.github.io/Upscayl/
may give better results, but as it is oriented against photos, I can imagine that TEXT still will be problematic (have not tried that).

OCR is most likely the best option; create "text" of it, then use a larger typeface/font.

Hannu
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