A raster graphic is An image that is pixel-based or bitmapped. It is one of the digital design file types you typically see when working with Photoshop.
How Raster Graphics Create an Image
Raster graphics form an image using a grid of square pixels. You can generate these images with raster programs, cameras, or scanners that blend the pixels to soften the transition from one color to another.
Converting an Image from Raster to Vector
Some programs cannot use raster formats and require vector graphics instead. But depending on your image, it can be time-consuming to convert an image from a raster to a vector format. To do so, you’ll need to trace over the original image to create the vector lines.
Raster Graphic File Type Extensions
You will see Raster graphics saved in the file extensions such as:
Additionally, raster images usually take up more space on your computer (depending on image quality). Large dimensions and detailed images require a larger file size.
When Should You Use Raster Graphics?
Raster graphics are ideal for images with complex compositions that include subtle chromatic gradations, faint lines, and organic shapes. For this reason, photo editing is better with pixel-based graphics.
Blended Colors Vs. Line Art
Vector-based images work best for line art, while raster graphics can use pixels to blend colors smoothly. These paint-like capabilities are not possible to re-create in a vector-based program.
Beware of Blurry Images
The biggest downside of Raster Graphics is that your image can become blurry when you scale it up. Since these images are pixel-based, you cannot enlarge the pixel dimension and resolution without losing quality.
The Limitations of Pixel-Based Programs
In short, you can’t add pixels where pixels don’t exist. If you use Photoshop to make the image larger, the program will randomly add pixels to increase the photo’s resolution. However, this will usually result in poor image quality.
Printing Raster Graphics
Printing a high-quality raster graphic depends on an image’s pixel dimension and resolution. 300 PPI (pixels per inch) is the minimum resolution for paper printing. While large format printers will have different size requirements based on how far away the sign will be. Depending on the distance, resolution requirements can range from 20 PPI to over 200.