How to patch transparent pixels ?

Bonaca · **Joined:** May 18, 2013 **Posts:** 27

GIMP Version: 2.8.4
Operating System: Windows
OS Version: XP - SP3
GIMP Experience: Beginner Level

I have a transparent .png - with Alpha channel.
To make a specific area non-transparent - I created a new layer, filled it with black and placed it just bellow the transparent pixels.
I expected that the image is not more transparent on the pixels where the black background exists, but - it is.

How can I resolve this, pls.

Gino D · **Joined:** Nov 06, 2012 **Posts:** 239 **Location:** Italy

You can try to use the Levels tool, where first of all in the dialog box you will have to select the "Alpha" item from the Channel drop down menu if you want to operate only on the transparencies of the original layer.
The Input Levels section allows you to gradually increase the opacity of the semi-transparent pixels by moving the gray triangular slider and/or the white one to the left.
Regarding the Output Levels widget, instead, there is the possibility of making the whole layer more and more opaque by progressively moving the black triangular slider to the right.

http://docs.gimp.org/en/gimp-tool-levels.html

Bonaca · **Joined:** May 18, 2013 **Posts:** 27

Thanks Gino D, I will try.

ofnuts · **Joined:** Oct 25, 2010 **Posts:** 4812

Bonaca wrote:

GIMP Version: 2.8.4
Operating System: Windows
OS Version: XP - SP3
GIMP Experience: Beginner Level

I have a transparent .png - with Alpha channel.
To make a specific area non-transparent - I created a new layer, filled it with black and placed it just bellow the transparent pixels.
I expected that the image is not more transparent on the pixels where the black background exists, but - it is.

How can I resolve this, pls.

Your image cannot be more transparent at a given pixel that the less transparent pixel in the layer stack. So your black layer must be somewhat transparent without you noticing it. Make all other layers invisible, start the Pointer dialog (Windows/Dockable dialogs/Pointer) and check the alpha value while you move the pointer: does it remain at 100%?

Wallace · **Posted:** Sat May 25, 2013 10:35 am **(#5)**

Bonaca wrote:

GIMP Version: 2.8.4
Operating System: Windows
OS Version: XP - SP3
GIMP Experience: Beginner Level

I have a transparent .png - with Alpha channel.
To make a specific area non-transparent - I created a new layer, filled it with black and placed it just bellow the transparent pixels.
I expected that the image is not more transparent on the pixels where the black background exists, but - it is.

How can I resolve this, pls.

I tried to recreate what has happened to you.
I first created an image with an alpha channel and made sure that it was transparent. I painted a few green peppers on this layer, then saved this one layer as a .png image, preserving the transparency.
I opened this image again, created another layer, filed it with black and placed it below the original layer that has a transparent alpha channel. I then went to save this image and turned of the black layers visibility, by clicking the eye next to the black layer.
I saved the image as a .png.
In the save dialog that is used for .png images it asked me if, A: Wanted to flatten the image and B: Save visible layers, I clicked save visible layers.
My image still had transparency and the black layer was not saved because it was not visible.
I tried many other things to attempt to recreate what has happened to you and this was the only way that I could attain the same results.
Maybe your black layers visibility was turned off, when you were saving the image as a .png?