2D Bitmap Graphics

Bitmap images are also known as raster images, they are made up of pixels in a grid, these are small dots of colours which together form what is seen on the computer screen.

Bitmap graphics are dependent on resolution, resolution is the amount of pixels that are in an image, this is usually seen as dots per inch (dpi) or pixels per inch (ppi).

Since bitmaps are dependent on resolution this means it is hard to re size an image, if the image is increased in size through the use of the software's re sample or re size command then it has to create new pixels, the software then has to estimate the colour values of the new pixels, this leads to a great deal of quality loss, when an image is decreased in size through the use of the soft wares re sample or re size command then pixels are lost, this also leads to a loss in quality.

Scaling is different to using the soft wares re sample or re size command, scaling is when an image is re sized by using the edges of an image to re size it, when a bitmap image is stretched to be larger then it gives the image less quality and a jagged appearance since it is decreasing the ppi, when a bitmap image is shrunk then it gives the image a higher quality since it is increasing the ppi.

All scanned images are bitmap images, and also all photo's taken with a digital camera are also bitmap images.

Common bitmap formats;

• BMP - Bitmap File Format
• GIF - Graphics Interchange Format
• JPG/JPEG - Joint Photographic Experts Group
• PNG - Portable Network Graphics
• PCX - Personal Computer eXchange
• TIFF - Tagged Image File Format
• PSD - PhotoShop Document