bug#51596: image-transform-resize has inconsistent semantics wrt scaling up/down

[Stefan Kangas <stefan@marxist.se>]

Juri Linkov <juri@linkov.net> writes:

>> I made a quick review of other image viewers:
>>
>> emacs                  gthumb          geeqie                eog
>> -----                  ------          ------                ---
>> fit height and width   Automatic       Zoom 1:1              Best fit
>> <missing>              Fit to window   Fit image to window   <missing>
>
> What is “Fit to window”?  Does it distort the image
> by changing its height/width ratio?

No, it preserves the aspect ratio.

>> Perhaps we could even have a "smart" option that only scales images up
>> larger than some height and width, and otherwise leaves them in their
>> original size.  That's probably the one I would like to use, now that I
>> think about it.  (I usually prefer to scale images up, but as you point
>> out it's pretty useless to scale small icons to fit the window.)
>
> Maybe a new user option (disabled by default) could scale up
> like ImageMagick's '-resize' does.

What does that option do?  (And yes, I imagine the above "smart"
resizing idea to be both optional and separate from the standard
options.)