What does it mean to Rasterize an Image?

Rasterizing is the process of converting a vector image or graphic into a raster image or bitmap. In other words, it transforms an image defined by shapes, lines and curves (mathematical coordinates) into an image defined by pixels, where each pixel has a specific color.

Why Rasterize an Image?

Although vector images have many advantages, there are situations where rasterizing an image is essential or more convenient. Let’s look at some of the key reasons for doing so.

Media and Platform Compatibility

Many digital devices and platforms, especially those that have been in use since before the popularity of vector graphics, are designed to work with raster images. Raster images, such as JPEG, PNG and GIF, are widely accepted and compatible with a wide variety of devices and applications.

Detailed editing

Raster image editing programs, such as Adobe Photoshop, allow artists and designers to perform pixel-level edits. This means that you can have extremely detailed control over every aspect of the image, something that is simply not possible with vector graphics.

Specific effects

There are certain effects, such as blurs, flares, and texture manipulations, that are inherently raster and require a raster image base to apply properly. If you try to apply such effects to a vector graphic without rasterizing it first, the result may not be as desired or may simply not work.

Printing

Although modern printers can handle vector graphics, there are still many situations where images need to be rasterized to ensure that they print correctly. Rasterization ensures that the image is translated into a series of dots that the printer can understand and reproduce accurately.

File size optimization

In some cases, especially for web, it is essential that images have a reduced file size for fast uploads. Raster images, especially when compressed into formats such as JPEG, often have smaller file sizes than their vector counterparts.

Prevent unwanted editing

Rasterizing a vector graphic essentially“locks” it into its current form. This can be useful if you are sharing a design or graphic and don’t want the recipient to have the ability to easily edit the original work.

Visual Consistency

Vector graphics, while scalable, can look different on different platforms or software due to the interpretation of the vector data. Rasterizing an image can ensure that it looks consistent across different platforms.

Integration with existing images

If you are working on a project that already contains raster images, it can be easier and more consistent to rasterize vector graphics so that everything is in the same format. This can help maintain consistency in editing and manipulating the project.

Project-specific needs

Some projects may require technical specifications that dictate the use of raster images. For example, some video games may require raster sprites or textures instead of vector graphics for better integration and performance.

Performance and processing speed

While vector graphics are wonderful for their scalability, they can also be more resource intensive when it comes to rendering or display. Raster images, on the other hand, can often be loaded and rendered faster in certain contexts.

Limitations of Rasterization

While there are situations where rasterization is necessary or desirable, there are also significant limitations associated with the process. Some of these limitations are listed below:

Loss of scalability

One of the greatest advantages of vector graphics is their scalability. They can be scaled up or down without loss of quality. However, once they are rasterized, you will lose this capability. If you try to increase the size of a raster image, it will look pixelated or blurry.

Increasing file size

Vector graphics, especially simple vector graphics, often have smaller file sizes than high-resolution raster images. When rasterizing, it is possible for the file size to increase significantly, which can be problematic for the web or storage.

Irreversible editing

With vector graphics, it is easy to make changes to individual elements of the design. However, once rasterized, separating and editing individual components (such as shapes or lines) can be complicated or impossible without advanced editing tools.

Loss of quality when editing

Raster images can degrade in quality with repeated edits, especially if saved in formats that use lossy compression, such as JPEG. Each time an edit is saved, the quality may decrease slightly.

Color limitations

While vector graphics are based on mathematical formulas and can represent colors accurately, raster images have limited color depth based on their bit depth. This could lead to a less accurate representation of colors in certain circumstances.

Manipulation limitations

Transformations such as rotations, distortions, and scaling are often best handled with vector graphics. When performing these manipulations on raster images, you may face a loss of quality.

Loss of layer information

When rasterizing a design that has multiple layers (such as text on a shape), these layers will be merged into one. This can make future editing difficult as the individual elements are no longer separated.

would you like to learn about other important concepts in graphic design and editing? Don’t miss our graphic design glossary where we tell you everything you need to know to become a professional.