Re: [Gimp-user] Change background colour with GIMP 2.10.22

[Zoltán Kluik <numizmatikakz gmail com>]

Dear Lim,

Wow, with this fuzzy tool it works excellent. You write so exactly and
precise, also it is really very fast process. I was blind that I wanted to
do only with foreground selection tool. This is better what You said
I have only point 9 which is not working. When I do Image --> Crop to
content or Zealous crop the GIMP said: Cannot crop because the image is
already cropped to its content. (Here the background is white and on the
picture there is only the coin.)
Thank You for Your help in advance.

Zoltan

Liam R E Quin <liam holoweb net> ezt írta (időpont: 2021. márc. 26., P,
0:09):

> On Thu, 2021-03-25 at 17:24 +0100, Zoltán Kluik wrote:
> > Dear Liam,
> >
> > Yes, the image is in RGB colour 8 bit.
> > What does it mean?
>
> Colour means as opposed to greyscale (just grey, no colur allowed).
>
> RGB means that any pixel can be in any colour, as opposed to indexed
> which would mean a fixed list of colours
>
> 8-bit means  each of red,  green, blue (RGB) can take any whole number
> value from 0 to 255 - this is appropriate for JPEG images for example.
>
> With the following image I did this:
>
> (1) open the image in gimp
> (2) select the Fuzzy Select tool from the toolbox
> (3) in Tool Options, make sure the threshold is good - i used 13. The
> higher  this number ,the more the Fuzzy Select tool will select colours
> that are not quite the one you click on.
> (4) i clicked on the green background 9still with fuzzy select). This
> selected eveything except the coin.
> (5) i used select->grow to increase the selection by 2 pixels. This
> makes sure that if e.g. there's a pet hair in the picture, it gets
> selected out. But this also selects the edge of the coin, which we
> don't  want.
> (6) then, i did Select->shrinl and entered 1 pixel, to get back the
> edge of the coin.
> (7) Probably we don't want an ugly hard edge so i used Select->Feather
> by 1.5 pixels to soften the edge of the selection.
> (8) i did edit->cut (or Control-X), to remove the green. If you don't
> have the default black and white colours selected in the two small
> panels  under the toolbox, press d to reset them to defaults and then
> do cut.
> (9) then i did Image->Crop to Content, to get rid of the extra white
> areas.
> (10) finally i exported the image.
>
> This is much faster to do than to describe. Maybe ten seconds at most.
>
> Just before exporting ,i actually also used  Colours->Levelsand pressed
> Auto Input Levels; you may not want that; it makes the dark  parts of
> the image black. You can get a better result by including a photo card
> (you can get them on ebay or from any photography shop) in the picture
> and using the white and the black as white and black points in Levels.
> It's pretty  much instant although then you have to crop the photo card
> out of the picture.
>
> Interesting coin.
>
> slave liam (ankh)
>
>
> >
>
> --
> Liam Quin - web slave for https://www.fromoldbooks.org/
> with fabulous vintage art and fascinating texts to read.
> Click here to have the slave beaten.