I want to use a specific palette to make it strictly index color.

[ken]

Additional information:
Indexed color conversion also fails in the recently released GIMP 3.0.0-RC2.
Also, when you select a color in an image with the eyedropper tool, it should select which color in the palette that color will become, but if the color is close to a color you already have (foreground color or background color), the selection may not be successful.

[Ofnuts]

(01-06-2025, 04:02 AM)ken Wrote: Additional information:
Indexed color conversion also fails in the recently released GIMP 3.0.0-RC2.

Should be better though. See https://gitlab.gnome.org/GNOME/gimp/-/issues/12579

(01-06-2025, 04:02 AM)ken Wrote: Also, when you select a color in an image with the eyedropper tool, it should select which color in the palette that color will become, but if the color is close to a color you already have (foreground color or background color), the selection may not be successful.

If the image is indexed, you should get a color which is already in the palette?

[ken]

(01-06-2025, 12:22 PM)Ofnuts Wrote:

(01-06-2025, 04:02 AM)ken Wrote: Additional information:
Indexed color conversion also fails in the recently released GIMP 3.0.0-RC2.

Should be better though. See https://gitlab.gnome.org/GNOME/gimp/-/issues/12579

(01-06-2025, 04:02 AM)ken Wrote: Also, when you select a color in an image with the eyedropper tool, it should select which color in the palette that color will become, but if the color is close to a color you already have (foreground color or background color), the selection may not be successful.

If the image is indexed, you should get a color which is already in the palette?

Thank you for your investigation there as well.
I tested it again here,

and it seems that the presence or absence of the bug depends on the index color conversion method.

Here is a reproduction of the bug.

The process is the same from Image → Mode → Index Color,

but with the color map,

the conversion works fine when I use "Generate optimal palette",

but when I convert using a custom palette, the problem occurs.

There are several conversion errors, but one example of an error is that palette numbers 165 to 168 are strange.

I have attached custom palette data (gpl) in the same order as the image, so please check it out.

[ken]

If the image is indexed, you should get a color which is already in the palette?

Sorry, I overlooked the question you answered. 
It is necessary to obtain palette information converted into index color. It is particularly important that we index correctly in the order of the palettes we created. 
This is because we are treating them as game images and after indexing we want to be able to arbitrarily decide how to change each palette number. 
We will use this to change colors such as the 2p color of graphics. 

Therefore, we want to be able to perform index color according to the colors set in the order we want.