Re: [Gimp-user] Sinc (Lanczos3) Option

[Liam R E Quin <liam holoweb net>]

On Wed, 2018-08-08 at 17:14 -0700, Lisa D. via gimp-user-list wrote:
> Thanks, everyone, for your help with this issue. I’m working with a
> jpeg
> that is 450x568 pixels @ 72 ppi/4.7x5.9”. I would like the dimensions
> to be
> 2.5” x 5.9”.

Your primary choices are to make it wider and then scale it down, or to
crop. Making it wider likely means duplicating some parts of the image
on the sides.

> Maybe it’s not possible to make an image longer in this way without
> giving it that fun house mirror look

Correct.

The resynthesize plugin (and others like it) can sometimes do it, but
with such a low resolution image it probably won't do a good job.


> , but I could have sworn I read online (maybe
> from the same guy who recommended gimp 2.4?) that it’s better to make
> a smaller image larger than to try to make a larger image smaller.

No, it's the other way round.

> That seemed counterintuitive to me as, like Liam mentioned, I’d be
> asking
> the image to invent detail that isn’t already present. Was my hunch
> correct? 

Yes.

> There is another version of this image I can purchase that is larger
> (1200x1514 px @ 300 ppi). Should I just buy this and shrink it? It's
> a bit
> spendy, but maybe that would be a lot easier?

It depends on what the picture is, but that's still the same shape.
However, you might be able to use the crop tool on it to choose a
rectangle that's the right aspect ration (in tool options you can set a
fixed aspect ratio for the crop tool, e.g. 4.7:5.9 in your case.

Note, thinking in terms of inches for a screen-resolution image doesn't
really work; images are rectangles of coloured dots, and the dots can
be drawn any size you like on the screen, although it looks ugly if you
can see them with the native eye. Apple's "retina" displays are closer
to 300 dots per inch in hardware, but one pixel in the image can be
displayed on a cluster of several dots on the display.

>  Or should I try to get GIMP
> 2.8 and see if by some miracle I can make my smaller image bigger
> without sacrificing quality?

It will still distort the image, like a fairground mirror, if you
change the aspect ratio. Always. And making an image larger always
loses quality, in one way or another. But with a larger image there's
more choices. Without seeing the actual image it's hard to know - feel
free to send email to me directly if you don't want to share the
details in public, and i'll take a look.

Liam (slave ankh)


-- 
Liam Quin - full-time slave for https://www.fromoldbooks.org/
with fabulous vintage art and fascinating texts to read.
Click here to have the slave beaten.