The process used to rasterize layers in Photoshop is fairly simple. Rasterizing a layer in Photoshop is the process of converting from a vector file to a pixel based file. The process is sometimes required for certain tools to function properly. The vector based format maintains perfect resolution on all borders while the pixel based version will lose that crisp, perfect edge.
Reasons to Rasterize a Layer
In many cases, rasterize in Photoshop is done because the program demands the change. You might attempt to perform an editing function and a prompt pops up requiring rasterizing in order to continue. At this point, you can simply comply and rasterize the layer, or you can choose a different direction or process.
Rasterizing is not typically a bad thing and the shift from a vector to pixel format is generally not noticed. The loss of perfect edges is not noticeable unless you zoom in intensively or blow up the image. If you plan to create a large format print of the image, for example, the pixelation caused by rasterizing may become noticeable. If the photo will remain in a standard size digital format however, rasterizing will have no noticeable impact.
At this juncture, you essentially must determine if the edits are more important than the pixelation. In most cases, rasterizing is the best route as it opens the door to more editing options. In the case of a large format physical print however, avoiding the rasterizing or working through the edits in a separate test file is the best course of action.
How to Rasterize an Image
The prompt to rasterize the layer is typically triggered when you attempt to implement a filter or tool that is only compatible with the pixel format. The eraser, paint bucket and brush tools are all designed to work with pixel formats, and they will not function on your vector file.
Keep in mind that when you move forward with the rasterize process, any text in the layer will become permanent. If you wish to edit the text size, shape, font and general appearance, do so before rasterizing. Alternatively, delete the text before rasterizing, and add a new text box after the process is completed.
When you are ready to rasterize, make a duplicate of the layer and save the original vector version. This preserves the original along with the option to return to the vector format if the pixel version is substandard quality. Choose to Rasterize and a number of options will appear.
You will see options to rasterize the shape, the fill content, video content, etc. Each option is relative to a specific element on the file. Choose to Rasterize Layer and this will convert the selected layer only. All of the vector content on the selected layer will convert and you will have access to all tools. Now the layer is a pixel format that is ready for manipulation. You will not have the option to make edits and return to a vector format.
Alternative Routes
Not many workarounds are possible for rasterizing but a few creative options open limited editing alternatives. One easy option is possible by creating a blank layer to overlay on the image. The vector layer remains intact and you can paint on the new layer to alter the appearance. The vector will retain perfect edges while receiving edits on the overlay.
The paint bucket is used to change the fill color of a shape and it only works in pixel format. The vector file has a fill color option and you can easily alter the color of the shape. You simply will do so without using the common paint bucket. Select the shape and click on Properties. Choose your desired color to change the fill color on the shape.