I recently downloaded a pack of TIFF mountain brushes for usage in Blender so I could sculpt my own terrain to look more realistic. The brushes can be downloaded here: https://www.youtube.com/watch?v=40glxZCyPeY
I brought one of the TIFF textures in and began using an anchored sculpt brush to place them down onto the subdivided mesh I prepared. However I noticed that the actual brushes were green, unlike a white colour list most brush alphas you'd expect. The brush strength is incredibly weak; even when turned up to 1.000 strength it is very weak and does not make much of a difference (see below). Notice how the texture is green in colour.
I thought I could go to GIMP and edit the images to be white, but when I loaded the TIFF file into GIMP the image is invisible, leaving only the dimensions of the image and nothing else. Perhaps I shouldn't be asking a question like this here but I am stumped. How can I make the images black and white without them turning invisible?
UPDATE: Tried out a method suggested to me. It makes the texture more usable but gives off these ugly rigid shapes on the sides of the mountain that don't look very clean.