Re: Image transformation filter for upscaled images

[Alan Third]

On Sun, Mar 07, 2021 at 10:12:43PM +0300, Evgeny Zajcev wrote:
> Currently, image transformation for upscaled images uses NEAREST filter,
> which is fast, but renders very bad results for images with text inside.
> 
> Maybe change it to GOOD, which is also fast, but renders more decent results
> 
> Here is I've got two screenshots showing the difference:
> 
> NEAREST (currently hardcoded in Emacs) -
> http://lgarc.narod.ru/pics/upscaled-nearest.png
> 
> GOOD (my proposal) - http://lgarc.narod.ru/pics/upscaled-good.png
> 
> What do you think?

See also bug#38394.

The reason nearest was chosen was because scaled up pixel art (emojis,
mostly, like etc/images/smilies/wry.xpm) looked abominable when using
the "best" filter, but most other types of images look OK when using
nearest. On the other hand the bug report complains that scaled up
pixel art looks abominable with nearest, so clearly there's a
difference of opinion.

I don't know whether "good" is a better compromise, I suspect it looks
quite like "best".

I don't know what the best option is, I suspect there's no clear
one-size-fits-all winning strategy.

-- 
Alan Third