Original picture
final effect
1. Open the original image material, copy the background layer, and use the Neat Image filter to reduce noise.
2. Click the channel panel, select the green channel and press Ctrl + A to select all, and press Ctrl + C to copy. Then create a new channel and press Ctrl + V to paste to get the Alpha 1 channel.
3. On the copy of the green channel, go to Filter > Other > High Contrast Preserve and set the value to 10.
4. Execute: Image > Calculate, set the parameters as shown below, and then calculate 3 to 4 times continuously after confirmation.
