Re: [Gimp-user] New User Need Help Enlarging/Enhancing Image

[Ken Moffat <zarniwhoop ntlworld com>]

On Mon, Aug 13, 2018 at 02:31:37PM -0400, Matthew Woehlke via gimp-user-list wrote:
> On 2018-08-13 13:09, Partha Bagchi via gimp-user-list wrote:
> > The image is 2048x1536 (3.1 MP). Best you can hope for is an 8 by 10.
> > That's inches. If you are willing to sacrifice quality further you can try
> > printing in 150dpi which would give you 14 by 10.
>
> I'm not sure I'd go even that big. The original was twice that
> resolution and had a lot less JPEG artifacting.
>
> Actually... you might be going about this all wrong. If you really want
> to use this to produce a very large physical print, I would consider
> embracing that the original image is smudgy by upsampling it (maybe to
> 7200x3600 if not 14400x7200 after cropping it to 2:1) and then applying
> some of gimp's artistic filters to achieve a look that is more
> "painting" than "photograph". This will make some of the lack of
> quality in the original irrelevant. At least give it a try digitally; if
> you don't like the result, all you've lost is some time.
>
> Also, make sure you save the result at least as a JPEG with 98% to 100%
> quality, if not PNG.
Since I had the 2048 version and opened it again to look at some
details of the g'mic interface when answering a question elsewhere -

If Nick has the g'mic plugin, look at its options - for me, this
image benefits from Details -> Local Contrast Enhancement (default
settings) - that appears to improve resolution in the main parts of
the pier, and makes the water shinier, but maybe manipulates the
colours in ways Nic doesn't like.  I've no idea what the original
colours were, it's a sunset shot.

There are also lots of other filters in g'mic, and for this image I
think the film emulation options might be useful (particularly
slide, but maybe also colour print) - look at the 'preset' option in
each, the results differ greatly (e.g. some of the fuji presets give
bold warm colours here, others seem much colder or less-sunset).

And, of course, the sharpening filters in Details : I'm now getting
used to using the gimp's default settings for the GEGL unsharp mask
(I used to use the old unsharp mask, which is still available), but
g'mic has several more sharpening filters that I occasionally use.
Hint - for *onscreen* display, zoom to 100% and scroll around the
image - some filters look ok when the image is less than
screen-size, but zooming in to 100% may show oddities.

As always with photo manipulation, experiment and keep notes (and
backups, both for the photos and the notes!)

ĸen
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