Image files are of two types

Bitmap and What?
A young university student once ask me about image file formats. As I was explaining, he interrupted and said "bitmap and what?" In general Image files are of two types .


Bitmap files are also called Raster files. Bitmap images are made up of pixels in a grid. The size of the grid is based on the image's resolution. For example, a bitmap-based image of 1 inch x 1 inch with a 600 dpi resolution would be defined by a grid of 600 x 600 pixels. A bitmap-based image is like a mosaic of pixels with each pixel holding a specific color value.
Bitmap-based files are more suitable for photo-realistic images that require complex color variations. They are, however, not easily re-sized because each bitmap-based image is mapped to a non-flexible grid. If a bitmap-based image were to be enlarged, it would lose sharpness – the edges within the image would appear to be jagged or fuzzy.
Scanned images and images from a digital camera are bitmap files.
    Here is a list of the most common bitmap file formats. There are many others but these are the ones you will most likely encounter.
  • jpg (Joint Photographic Experts Group)
  • tif (Tagged Image File Format)
  • png (Portable Network Graphics)
  • gif (Graphics Interchange Format)
  • bmp (Windows bitmap format)
  • psd (Adobe PhotoShop Document)
  • psp (Corel Paint Shop Pro
Vector-based images generally contain well-defined elements such as curves and shapes of various colors. Each element is defined mathematically by the computer. For example, if a vector-based image contains a red dot, then information such as the location of the circle's center point, the length of its radius, and the color red would be the essential information for this image file.
Vector-based files are more suitable for illustrations that require precise measurements. They are also easily re-sized due to their mathematical nature. However, the vector-based file format has its drawbacks as well. It is not good for displaying photo-realistic images such as a photograph because images of this type generally do not contain well-defined shapes and curves.
    The following vector file formats are the most common and the ones you are most likely to see.
  • svg (Scalable Vector Graphics)
  • eps (Encapsulated Post Script)
  • ai (Adobe Illustrator)
  • cdr (Corel Draw)

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