Lanczos upscale - FYI

I did a video yesterday about upscaling - Topaz Gigapixel AI vs ACR super resolution vs Photoshop Preserve Details 2 and RT Lanczos.
So if you don’t know how to setup Lanczos then the relevant section is here


thank you for sharing!


Thanks you Andy, I found the forum through one of your YT videos. I’m super interested in Lanczos upscaling.

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Hi Andrew, and cheers!

Yes, when I get asked for a big print, I most often upscale this way, then add the required print output sharpening.

Hi Andy,
I hope it’s ok, I messaged you via the contact email on your website. in my email I was essentially asking if by making an enlarged print and sharpening the enlargement I can downsize the image and produce a sharper better print in a small size. If for example my native resolution allows me to make a 30" print without upsizing would that same 30" print be sharper doing the Lanczos upsize? At this early stage I don’t even have RawTherapee on my computer, so I’m really in at the beginning.

You’ve sort of lost me there Andrew! How you going to downsize a physical print??

Or do you mean enlarge the image, then sharpen, then downsize?

If you do, then it’ll make little to no difference to your final image, especially if you maintain the same ppi resolution during the upscale and downscale process.

If you went from 30" to say 60" you would double the pixels, then halve them going back to 30" so the net gain would be nothing.

You would be better off changing the output DPI at the print head while maintaining the original physical dimensions.

Ah yes, sorry I didn’t mean downsizing a physical print!

You wrote “If you went from 30” to say 60" you would double the pixels, then halve them going back to 30" so the net gain would be nothing."

I understand this, but I’ve been led to believe that by doing this you can create a sharper print. Although I have to wonder, if you make an 80" print that’s perfectly sharp and if this so called method works, then surely by downsizing it’s going to be too sharp.

I’ll be honest, i think I’ve been listening to a lot of BS and getting confused.

@sanfairyanne Also: do not forget
to take “viewing distance” into consideration.