When
you create a rasterized shape, you’re drawing and rasterizing a
shape and filling it with the foreground color. You cannot edit
a rasterized shape as a vector object. Raster shapes are created
using the current foreground color.
Select a layer. You cannot create a rasterized
shape on a vector-based layer (for example, a type layer).
Select a shape tool, and click the Fill Pixels button in
the options bar.
Set the following options in the options bar:
Mode
Controls how the shape will affect the existing pixels
in the image. (See List of blending modes.)
Opacity
Determines to what degree the shape will obscure or reveal
the pixels beneath it. A shape with 1% opacity appears
nearly transparent, while one with 100% opacity appears completely
opaque.
Anti-Aliased
Smooths and blends the edge pixels with the surrounding
pixels.