Changes not being applied

[Kjen]

Hi everyone,

I am simply trying to make a picture of a molecular formula darker. When I use the brightness-contrast tool or the levels tool, the preview shows the desired result, but when I press okay it reverts to the original. What can I do to remedy this?

[rich2005]

I can not reproduce that so maybe a little more information or better still, post a typical image.

Image format - RGB/indexed,Greyscale - number of layers, a screenshot such as this often gives most info. https://i.imgur.com/BoaXCTb.jpg

As an alternative have you tried Colors -> Auto -> White Balance Of course depends on image but often works.

[Kjen]

The language is Dutch, but I hope the key paramters can be understood. If not, I will change the system language. In the picture it can be seen that the preview shows the desired result, namely a darker structure. When I press okay however, it reverts back to the original

[rich2005]

Ouch... that looks like a nasty bug. Your screenshot is fine. I can reproduce that.

From your screenshot, that little diagram is in a transparent layer.

Try:

1. Increase the precision to 16 bit floating point. (sRGB or Linear) Image -> Precision



2. Now do the color adjustment, I am using brightness/contrast since levels is not very effective on the (very) dim image.



3. OK that and it should work



4. Do not turn back to 8 bit save the gimp.xcf as-is or export as a 8 bit RGBA png

I will do a few more tests and post a bug-report.

[Blighty]

(03-25-2019, 01:23 PM)rich2005 Wrote: Ouch... that looks like a nasty bug. Your screenshot is fine. I can reproduce that.

I can't reproduce it. Works fine for me.

[rich2005]

(03-25-2019, 01:45 PM)Blighty Wrote:

(03-25-2019, 01:23 PM)rich2005 Wrote: Ouch... that looks like a nasty bug. Your screenshot is fine. I can reproduce that.

I can't reproduce it. Works fine for me.

Try the attached, see what works or not

@Kjen another try: Using an 8bit image. In the levels dialogue use the alpha channel 

[Blighty]

(03-25-2019, 01:55 PM)rich2005 Wrote: Try the attached, see what works or not

I see on your example the background is 255,255,255,0
and text/lines is 0,0,0,50
Took me a while to even create a layer like that.

Then tested on your example and my creation. The following worked on both. Changes stick.

[rich2005]

A bit of a guess from OP's screenshot. Typically little diagrams from some colour-to-alpha removed background then pasted in as new layers.

The point about the bug is; taking say, Adjust Brightness and Contrast on an 8 bit image, the preview should not even show that improvement. Try doing that in Gimp 2.8

[Kjen]

Changing it to the 16-bit floating point did the trick. Thanks a lot!