hi,

I am new to gimp and I wanna use it just once at the moment and I am not planning to get any near professional.

I try to make a image with background and several foreground images that blur into the background at their borders. I found out that I can do so with "add layer mask" -> "layer`s alpha channel" and then using the gradient tool. Problem is, it is working fine and as expected for two of my images. but the third one just disappears after adding this alpha channel layer mask. all images are jpg. any suggestions? thanks for help. please be lenient for using maybe wrong terms or something and explain things as I were a child. I used a little photoshop like twenty years ago.

Hi palmovitsch,

Welcome to gimp chat.

Your layer disappears because it's layer mask is all black. When drawing on a layer mask, white is fully visible, black fully invisible and greys in between.

If you want to start off fully visible do:
Layer -> Mask -> Add Layer Mask
And then choose the radio button:
White (full opacity)

That's just how the mask is initialised, you can change it after that e.g. by filling with a gradient as you have been doing.

If you want your all back mask to be different you can click on the layer mask in the layers dialog and then change it anyway way you want. Some examples of different things you can do, but you can do just about anything:

Use the gradient tool to fill with a gradient as you have been doing.

Use any of the paint tools like paintbrush to draw on it.

Edit -> Fill with FG Colour to fill with the foreground colour.

Filters -> Blur Gaussian Blur to soften the edges.