Shape, line, image and text 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, image or text layer:
On the Layers panel, select a layer, then choose one of the following from the Merge and Rasterize pop-up menu:
Rasterize—Rasterizes the selected layer.
Rasterize & Trim—Rasterizes and trims off-canvas content from the selected layer. Previously recorded macros will trim.
Rasterize To Mask—Rasterizes the selected layer as a mask layer.
To rasterize a shape, line, image or text layer: