Some of the texture effects in this tutorial are done inside the channel. The advantage of this is that it can be easily called. Many filter effects can use textures from existing channels. This eliminates the need to re-texture.
final effect
1. Open the wall material shown in the picture below, click on the channel panel, create a new Alpha1 channel, and execute the "Cloud" filter.
2. Copy the "Alpha1 copy" channel, adjust the color levels, enhance the contrast, and perform inversion to obtain the correct selection.
3. Copy the "Alpha1 Copy 2" channel, continue to adjust the color levels, and enhance the contrast again.
