selection not hard when erasing

[usul]

Hi,

I want to erase part of an image.

First, I select the object I don't want to erase with the magic wand tool. I invert the selection.

When I use the eraser it seems to work. But when I zoom in to pixel level, I see that pixels are erased inside the selection. (not much and only at the border) How can this be?????
Am I missing the general concept?

[Colin Walls]

The effect of the magic wand is subtle. What it actually selects obviously depends upon where you click - it will select pixels of teh same colour. The tolerance setting determines how far "out" a colour may be and still get selected. If you have "anti-aliased" checked, you will get fuzzy edges on your selection. I think this last point is key to you.

[usul]

Yes you are right, thank you. It was the anti-aliasing.