Photoshop need help with map area measuring.

[feanaaro]

@Azelor: The layer only contains solid shapes 100% white. The only thing that could plausibly change whether a pixel is "counted" or not is anti-aliasing, and in fact de-selecting anti-aliasing I get a consistent count between the equivalent selections. I believe the wand selects on both color and opacity, anyway, though that is not relevant in this case.

@Jalhya: it's the first one, and I am subtracting the empty space, not the white space (which is what I want to count).

It all works fine and consistently by de-selecting anti-aliasing, really. Sorry for the induced confusion.

[Ilanthar]

I may miss the point here (I confess I haven't read everyone's post), but I use a little free software called "ImageJ" which is quite efficient to mesure a pixel area.