Kendra Schaefer

You’ve probably seen Photoshop prompts that ask you whether or not you’d like to rasterize your text, shapes or layers. Hard to give Photoshop an answer when you don’t know what rasterizing is, exactly. The Wikipedia article on the topic is unusually unhelpful, stating, “Rasterization or Rasterisation is the task of taking an image described in a vector graphics format (shapes) and converting it into a raster image (pixels or dots) for output on a video display or printer, or for storage in a bitmap file format.”

Riiight… So let’s see if we can clear that up for all you Photoshoppers.

What does rasterizing text mean in Photoshop?

I’ll skip all the technical details about rasterizing and pixel counts and display ’cause hey, who cares? Basically, when you rasterize a layer, you turn it into a picture that can no longer be edited the way it was created.

For example, if you rasterize text, it’s no longer text. It’s a picture of text. After it’s rasterized, you can no longer use the type tool to change what you wrote. You now have to treat that rasterized text as a picture, using an eraser tool to erase parts of it, or using the color tools to change its hue.

If you still don’t understand, imagine the difference between typing the word “Hello!” in a text file, and painting the world “Hello!” on a canvas. With the text file (unrasterized text), you can select each letter with your cursor, make it bold, change the font, etc… the text is treated like text. If you paint the word on a canvas, you can’t use a cursor or text tool to manipulate that word. You have to paint over it or erase it to change it. Rasterizing text is like converting a text document to a painting.

What about rasterizing a shape?

With shapes, it’s essentially the same thing. If you rasterize a shape, it’s no longer an entity whose edges can be edited or manipulated using the shape tools – it becomes a solid, flat picture of a shape. In Photoshop, while something is still a shape, you can’t erase it using the erasers, but you can erase a rasterized shape.

A shape in Photoshop, while it is unrasterized, is a “vector”.

What is a vector?

Again, skipping the techno-babble, a vector shape or image is an image that can be resized however big you want it or however small you want it without it losing its integrity. A vector image is kind of smart. In a way, it stores enough information about itself to let you resize it, and it still keeps its sharpness. A vector circle could be resized to 1000″ x 1000″, and guess what? It won’t be blurry, it will stay perfectly round, and the edges will be as crisp as the day they were born.

What is a raster image?

A raster image is a picture. A flat, stupid picture that doesn’t know much about itself at all. It has a certain number of pixels per inch, and it plans to stay that way. You might be able to re-size it by stretching it out in Photoshop or another program, but the bigger you make it, the blurrier it gets, and if you make it too small, it will be miserably distorted.

As a rule, rasters do a lot better when they’re made smaller than when they’re made bigger.

Jpgs and photos are rasters. Images that you make with your paint brush in Photoshop are rasters. Gifs are also raster images. Any picture that you download online is probably a raster image. It’s a flat picture, and you can’t really edit individual elements of it, because it’s so dumb, it doesn’t even know those elements are there.

Why and when do I have to rasterize my shapes and text in Photoshop?

Depending on what you want to do, you don’t necessarily have to rasterize anything. When you save your final .psd file as a .jpg, .gif or .bmp image, Photoshop basically smooshes all your layers down into one flat raster image for you.

There are certain functions in Photoshop that you can only perform on a rasterized layer that you can’t perform on a vector or text layer. Allow me to illuminate.

Example One: You type some text, then you grab your paint brush and try to paint something. You don’t want to paint ON your text directly, you just want to paint in the Photoshop document you’re making. But you get this error: “This type layer must be rasterized before proceeding. Its text will no longer be editable. Do you want to rasterize the type?”

You’re getting this because Photoshop thinks you want to paint with your paintbrush directly onto the type. Why does it think that? Because you have a type layer selected. The paint brush tool creates raster brush strokes. The type tool creates non-raster text. So you can’t paint onto the letters themselves without first turning them into a raster.

To fix this problem without rasterizing anything, just go to Layer > New > Layer…, and click OK to create a fresh layer. Make sure that new layer is selected in your layers panel, and you can paint on that all you want.

However, if you do want to literally paint directly on your lettering, you must rasterize your type to do that. Then you can paint all over it. But you will no longer be able to edit your type with the text tools. It has become a picture.

Same solution if you want to use the eraser tool to erase your lettering, or apply a filter to your lettering. You cannot apply a Photoshop filter to unrasterized type. But you cannot apply text styles to type that has been rasterized. Why? Again, because it’s no longer type. It’s a picture of type.

Example 2: You’ve made a shape using your shape tools. Now you want to use the Eraser tool to erase part of it. But this error message appears: “This shape layer must be rasterized before proceeding. It will no longer have a vector mask. Rasterize the shape?”

You’re getting this error for the same reason you get the error in example 1. The shape you made with the shape tools is a vector – it is keeping track of enough information about itself to allow itself to be resized without pixellating. But you’re trying to treat it like a flat, inanimate, dumb raster picture.

If you want to use your eraser tool on the shape, by all means, rasterize it. If you’re trying to use your eraser tool on something else, and you keep getting that message, the problem is most likely that in your layers panel, the layer containing your shape is selected instead of the layer you want to be editing. Make sure the layer you want to erase is selected in that panel before you try to use the eraser.

Example 3: You’ve made a shape using your shape tools. Now you want to cut a piece out of it. You make your shape, you select the part you want to cut out, and you try to use Ctrl + X (or Mac / Linux equivalent), and strangely, the color of the shape floods your document.

In this case as well, the right thing to do is go ahead and rasterize that shape. If you’re new to Photoshop, rasterized shapes probably respond in a more intuitive way. Unrasterized shapes don’t.

Anything else I should know about rasterizing?

Because text and shapes can be resized without loosing definition, but rasters can’t, it’s always a good idea to make your text or your shape the size it will actually be before you rasterize it.

Think long and hard before you rasterize your shapes or text, because once you’ve done that, that’s it. It’s a picture. You lose the ability to edit your original in certain ways. What I usually do when I need to rasterize something, but I don’t want to lose my original in case I need to edit it some more, is I make a copy of the layer that needs to be rasterized. I hide one of the layers by clicking the eye icon next to it in the layer palette, and rasterize the other. Then, if I screw up in too dramatic a fashion, I can simply delete the rasterized layer, and start again with my original shape / text.