Raster format is a simple type of graphics representation, where an image consists of a raster (an array of two or, perhaps, more dimensions), and each item of this array is a graphical dot with its own color and, perhaps, other characteristics. This representation is a "physical" map of dots merged in an image.

Raster Format Data

The base of a raster image is a simple array of dots called a "bitmap" (this type of image contains in a popular BMP raster file format extension). For convenience, almost each other format of raster data packs these bitmaps by some way, from direct ZIP or LZH archiving to more complex schemes.

Raster File Format Example

This is no way to create a best raster format. Each raster type except BMP allows some compression for reducing a raster size. This reduction is a great necessity (for example, bitmap raster format data for modest 6000x4000 pixels with 8-bit color depth will take about 72 megabytes of raw space).

  • JPEG File (JPG) is the most popular raster format extension for photos, allowing compressing neighbor pixels into interpolated squares;
  • PNG File (Portable Network Graphics) is the “lossless” raster format that allows keeping all details and fine lines of an image intact;
  • GIF File (Graphic Image File) is the one of earliest raster format types, providing a bitmap picture with a possibility of animation and good compression rate but only a 256-color depth;
  • TIFF File (Tagged Image File Format) is another lossless format for graphics, allowing big color depth but often requiring biggest space due to many tags and attributes of this raster format.
  • RAW Files from different static image cameras (e.g., Canon RW2, Nikon NEF etc.), providing an unprocessed camera image, for converting a specific raster format to JPEG or TIFF files.

These are many other proprietary and open raster format types for different tasks, but those listed above are the basics for most graphic operations and software.

Raster Format vs Vector Format

The vector format for image files is more "logical" than "physical". In this format, each graphical object is a set of colored vectors or figures that have some coordinates and scaled relations between dots marking the margins of these vectors, as well as such attributes as color or gradient.

  • To convert raster format files to vector representations or vice versa, you will often require some vector graphic software, such as Corel Draw or Adobe Illustrator.

How to Convert Raster Format Files?

Sometimes you can have a need to change format of raster data, saving some image file under another raster format extension or even as a vector image.

  • To convert raster file format to another, just open it in a common graphic application (including MS Paint, GIMP or Adobe Photoshop) and export an opened file as some other type!

Note: Changing from a raster data compression format to another type, especially "lossless", often adds greatly to file size. For vector files, the size of an image depends from quantity of fine details and different textures.