Combine two channel masks.
This procedure combines two channel masks. The result is stored in the first channel.
| this |
The channel1. |
| channel2 |
The channel2. |
| operation |
The selection operation. |
| offx |
x offset between upper left corner of channels: (second - first). |
| offy |
y offset between upper left corner of channels: (second - first). |
|
TRUE on success. |