I need to slice few pieces off of an image

[christineavatar]

When I go to slice it I get a 'dead pencil'

 I made the fethered piece by removing the white background (I put the red behind it to make it visible for this photo). I am then going to add it to a character I have made in Illustrator and take the character into Character Animator. The problem is that Character Animator doesn't bring forward a mask so I am stuck trying to trim this picture to fit the shape precisly but the cutting tools won't work for some reason. Why when I try do I get a 'dead pencil' which indicates that none of the cutting tools will work? And how can I get them  - any one of them - to work?

[Monika Gause · Accepted solution]

You maybe want to use Photoshop for editing pixel images.

The slive tool is for web design and won't help you here.

The knife tool will only work on vector paths.

[christineavatar]

Thanks. This saved me a lot of grief!