How To fade one picture into nothingness

[Edward99]

Good morning all.

Huge GIMP fan.

I was wondering...and am sure you can do it, just haven't figured out how... to evenly fade a transparency.

The example below is 2 images, flag of Croatia and European Union.

So, the idea would be to apply an even fade out of transparency to the Croatian flag (top layer) to fade into the image behind it - European union flag.

If anyone can suggest how to do this, I'd be most appreciative.

It's not Tools/gradient, is it a mask I'm trying to evenly fade out?  Lost on this.

[Krikor]

Having the images on each layer;
Change the colors, from foreground and background, to black and white respectively; 
Create a layer mask and apply a linear gradient to the mask (Top layer). 

[PixLab]

To add to Krikor,
Put your image in 16 bit before adding the gradient (top menu, Image > Precision > 16 bit), or you will have banding and/or your merging gradient won't be as smooth as your example

   

   

[Ofnuts]

(02-21-2023, 05:42 PM)PixLab Wrote: To add to Krikor,
Put your image in 16 bit before adding the gradient (top menu, Image > Precision > 16 bit), or you will have banding and/or your merging gradient won't be as smooth as your example

Even in 8-bit mode you can avoid banding by enabling the "dithering" on the gradient:

   

Unless you are memory-constrained, if you want high precision use 32-bit FP linear light. This is the mode in which all computations are done, so you avoid conversions and round-off errors.

[Edward99]

(02-21-2023, 04:59 PM)Krikor Wrote: Having the images on each layer;
Change the colors, from foreground and background, to black and white respectively; 
Create a layer mask and apply a linear gradient to the mask (Top layer). 

Thanks everyone.  You know - applying a gradient to a mask never occurred to me.  Cool little effect to add to my arsenal.  Done right, it's a really cool effect to apply to an image.

Having said that, bear with me, THIS is what I got, when I executed your instructions....

I applied the IMAGE/PRECISION/16 BIT as the guy below said - appied it to the American Flag (top layer) - I left it at that (didn't apply to the bottom layer, chinese flag), because I assumed IMAGE hits everything in the project (As opposed to menu item LAYER which just hits that layer).

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(02-21-2023, 04:59 PM)Krikor Wrote: Having the images on each layer;
Change the colors, from foreground and background, to black and white respectively; 
Create a layer mask and apply a linear gradient to the mask (Top layer). 

Ok I think I got it now (unless you see something, some setting I have in that print screen that isn't right.

What I did was start applying the gradient at the half way point of the top layer and got something like this...




Which is what I was looking for - because I don't want to see the bottom layer until at least 50% into the top layer, which is kind of what's happening in the original example.  Even less... like at the 70% point into the top layer, THEN the European flag starts appearing. My mistake was applying the gradient to the entire top layer - when in fact I just want it for the last bit of the top layer (so I'd see 70% of the top layer, and 70% of the right layer - the remainder is the blend.

Thanks everyone.

[Ofnuts]

Depends a lot on the "blending function" of the gradient, and where the "midpoint" is. When you create the gradient, if you hover near the middle of the segment, you will see a dot in a circle. If you click, you make the gradient mid point appear.

• You can drag it along the segment to change the shape of the gradient
  
• In the on-canvas dialog, you can change the blending function (you possibly want one of the "spherical" ones)
  

[PixLab]

(02-21-2023, 06:17 PM)Ofnuts Wrote: Even in 8-bit mode you can avoid banding by enabling the "dithering" on the gradient:

The first image (8bit) in my previous post is with dithering checked, it is always checked on my computer, nonetheless I got banding...

See?