Shape, Line, Text and Image layers can be rasterized to create pixel layers. This "flattening" operation can be performed manually or automatically (when applying filters or retouch brushes).
Rasterization has various uses:
For when the appearance of complex vector gradients or effects needs to be honored, particularly for print artwork.
To convert a placed image layer to a pixel layer (for pixel manipulation). By default, many brush tools rasterize image layers before painting.
Inpainting: after cropping, inpainting may be used to tidy up an image's corners, but the inpainting may be using information outside of the crop area. Rasterizing will discard this information and force the inpainting to use only what is visible.
To rasterize a shape, line or text layer:
Do one of the following:
From Layer menu, select Rasterize.
On the Layers panel, -click a layer and select Rasterize.
To rasterize a shape, line or text layer and trim off-canvas content:
Do one of the following:
From Layer menu, select Rasterize & Trim.
On the Layers panel, -click a layer and select Rasterize & Trim.
To rasterize a shape, line or text layer to a mask: