2-ton wrote:
I tried desaturation, then levels to make it as black and white as possible without losing edges, then painted in where it needed, then copied that to a layer mask. It's ok, but I seem to remember there was a video where someone used a green channel to make the layer mask image.
Without seeing the image, its all guessing.
Yes, there is a technique using a channel to create a layermask. You choose the channel that has the best contrast - you can also use other channels (decompose in Gimp or G'MIC), like hue, saturation or luminosity, but it depends on the image !
You could also use a specialised brush (a triangle) in combination with a brush dynamic (tilt angle) to manually paint in the fur on a layermask.
There are tons of techniques on youtube for Photoshop. Most of the time they are very easy to convert to Gimp.
You guys must really start looking outside this little community. It has all been done already and search engines are at your fingertips.