Channels / transparency. How to make?

[leabreuh]

(05-30-2023, 02:25 PM)rich2005 Wrote:

Quote:....I need to leave image2 with the same opacity as the example of image 1 .....

OK, got it (I think)

You can try matching using sample points see: https://docs.gimp.org/2.10/en/gimp-sampl...ialog.html

Any difficulty is assessing matching sample points between images. In this example I chose the dark shadow under the collar.

Then it is applying the curves tool, in alpha mode and getting an alpha value in (2) to match the alpha value in (1)

45 second  example: https://i.imgur.com/JCgnduR.mp4

if it is saved in transparent png or webp, they do not look the same. Save to compare and then open both on a white background and notice the huge difference. 

[rich2005]

(05-30-2023, 02:51 PM)leabreuh Wrote: if it is saved in transparent png or webp, they do not look the same. Save to compare and then open both on a white background and notice the huge difference. 

OK, you are using a white background. Open the images as layers over a white background layer and move side by side

Again using sample points and the same judgement call, Spots on each layer that are equivalent. I chose this.

   

Note the  transparency sample is merged = 255 because of the white background.
Using the layer opacity slider, in image 2 layer, adjust making the RGB values the same as image 1 layer. Make a note of the value.

   

Apply that value to image 2

   

That opacity value is 59 but use your own judgement, maybe in the 50% to 60% opacity region.