What is a raster or bitmap file?

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Raster images are the most prevalent form of digital imaging. Most digital photographs are raster files. Many digital cameras automatically take and save photos as raster files, which is also the format you typically see images in online. Raster files are made up of pixels (hence the alternative name ‘bitmap’), which are tiny squares of color. The number of pixels in an image is its resolution. The more pixels there are, the higher the resolution, and the better the quality of the image. When you zoom in on a raster image, you will eventually see the individual pixels that make up the image.

Examples of raster file formats: JPEG, PNG, GIF, HEIC, TIFF, PSD, Webp, HDRI, EXIF, JPEG 2000, JPEG XR, DPX, PPM, PCX, PGM, ECW

When to use


Raster files are best used for photographs and digital paintings. It is best to use raster graphics when one needs a photo or an image with complex colors, gradients, and shading. Raster files are also the best choice for images used on the internet.

When to avoid


There are certain situations when it is best to avoid using raster files. When working with detailed graphics or illustrations, vector files will usually provide a more accurate representation. In addition, vector files can be scaled indefinitely without losing quality, whereas raster files will become pixelated if they are enlarged too much. Raster images are not always ideal for logos or illustrations because they can’t be easily enlarged without degrading in quality.



Raster files are made up of a grid of pixels, and each pixel contains a specific color or shade. When a raster file is scaled up, the pixels become larger and the appearance of the image becomes blurry or grainy. As a result, raster files are not as scalable as vector files.



Most software programs can open and edit raster files. They support most color modes. There are a variety of software programs that can be used to open and edit raster files. Many of these programs are fairly easy to use and can provide a user with a great deal of flexibility when it comes to working with these types of files.

File size


When it comes to file size, raster files are relatively large. This is because raster files contain a lot of data. Each pixel in a raster file contains color information, and there can be millions of pixels in a single image. The more pixels that make up a raster file, the higher the file size will be. However, even small raster files can be quite large, depending on the amount of detail they contain. For example, a photograph with a lot of fine details (such as a close-up photo of a person’s face) will have a much larger file size than a photo with very few details (such as a landscape). When dealing with raster files, it’s important to keep in mind that larger files will take longer to load on the web and may be more difficult to work with.

Image resolution & DPI


The resolution of a raster file is measured by its DPI. DPI, or Dots Per Inch, is a measure of printing resolution. The higher the DPI, the higher the resolution and the sharper the image will be. For raster files, DPI is determined by the number of pixels in the image. The more pixels there are, the higher the DPI and the sharper the image will be. Most printers can print at resolutions of 300 DPI or higher, so for most purposes, 300 DPI is sufficient. However, if you need to print at very high resolutions, such as for professional photography or graphic design, you may need to use a printer that can print at resolutions of 600 DPI or higher.

The DPI value has no bearing on the size of the printed image; it is solely concerned with the quality or “resolution” of the printed image. The term is usually used when referring to printers, but it also applies to scanners, digital cameras, and other types of output devices. DPI is not a concern when the final destination of the image will be displayed on a digital screen.

Editing raster files


In general, raster files can be edited in two ways: either by working with the individual pixels or by using filters and other effects to change the overall look of the image.



While it’s usually best to work with the file type that’s already been created, there are times when you might need to convert a raster file to a vector. Luckily, there are a few different ways to do this. One popular method is to use a program like Adobe Illustrator or Inkscape to trace the image by hand. This can be time-consuming, but it’s often the most accurate way to convert a raster file to a vector. Another option is to use a software program that specializes in converting raster files to vector files. These programs often have a learning curve, but they can save you a lot of time in the long run. Whichever method you choose, converting raster files to vector files can be a helpful skill to have in your toolkit.


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Leon Olagh

Leon Olagh is an experienced photo retoucher and editor. He shares insights and expertise in the field of photography through his blog posts. His work reflects a meticulous approach to the art of creating and refining visual content.

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