How to find dirt on alpha channel?

Question

Adobe Photoshop

There is a complex image, you need to carefully make an alpha channel for the hair.
The problem is that there is a lot of hair, they merge with the background, and there is simply not enough RAM for advanced automatic selection (old computer).
Through long manipulations, I was able to make them more contrasting against the background for the alpha channel, and it seems that I even brushed the bad places manually with brushes.
Now there is one problem left - There are a lot of pixels barely distinguishable from black in the photo, next to the hair, can they be removed somehow? or at least highlight the black color, and there I will remove all the dirt myself.

A piece of the editable image.

Answer 1

You can invert the image or put contrasting colors under the hair to visually highlight the artifacts. And then the eraser will help you.