here are basically two types of digital images; Object oriented and bitmapped image. Object oriented are also known as vector graphics, which are created by the use of mathematical equations. Each object-oriented image is an object by itself. It can be manipulated and resize without any loss of quality.

   The second type of digital image is bitmapped image. Also known as raster image. It is a data file or structure, which corresponds bit for bit with an image displayed on a screen. Bitmapped image is static image that when manipulated, the quality of the image is affected to certain degree. Bitmapped image is the most exact duplicate to the original image it can be. There is no compression or other methods used to decrease the size of the image. Therefore the quality is as good as it can be.

   There are many factors in which determines the quality of the bitmapped image. Here are some examples. Resolution can vary from image to image. The higher the resolution, the better the image. Resolution of an image is determined by the hardware initially. Resolution can be increase or decrease. The result of the change will affect the quality of the image display.

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This bitmap image - size 82kb, to save downloading time the image is replace with a gif format. !

   The size of the image is determined by the quality of the image. Resolution and pixels per inch are two important factors that determine the size of the bitmapped image. If an image has more pixels per inch, the quality of the image will be better. At the same time, the size will be bigger. The resulting image display will be a lot cleaner.

   A bitmap image is characterized by the width and height in pixels. The number of bits per pixel, which determines the number of shades of gray or colors the pixel in any given image, will determine how many different colors the image has. To have a higher color palette, the bit per color must be higher (More 1's and 0's per color).

• A pixel with 8 bits per color gives a 24-bit image (8 Bits³ colors has 24 bits) 24-bit color resolution is 16.7 million colors.
• 16-bit color has 65,536 colors (Standard for Macintosh Computers).
• 8-bit color has 256 colors (Standard for Microsoft Windows).
• 4-bit has 64 colors or shades of gray.
• 2-bit is black and white only.

   Color can go higher than 24 Bit. 32 Bit are very common on today's video accelerators. Bitmapped Images doesn't need any higher bit to get the quality needed.

How BMP is displayed?

   A bitmap image being display on screen is simply a matrix of pixels that maps out the various color palettes to represent an image. Thus for a given image of the same size, One image with a higher pixel per inch count will have a better display quality because the pixels will be closer together and more variation of color palettes can be display pixel per inch of a given image. Higher Bit Color resolution will provide a higher quality image. To obtain the best image quality of a bitmap image, the video accelerator, Screen display and the actual bitmap itself must have a common denominator. For example, if the Bitmap is 24 bit color. The Monitor can display up to 32-bit color resolution. But the video accelerator can handle only up to 16-bit, the resulting display on the screen will be 16 bit. If everything is 32 bit, the resulting display will be the best quality for the image in 32-bit color.

   A method used to work around this problem is Color reduction - Which reduce the color down to the common denominator for all parties involve in the display (Image resolution, Video accelerator and monitor etc). The example in the above paragraph, the image is reduced from 24-bit color to 16-bit color so it can be display properly. Most of the time, reducing the color from a 24-bit to a 16-bit display, the notice is minimal. But reducing the color from a 24-bit to an 8-bit color is a drastic difference.

   Another method commonly used is dithering which simulate colors that are actually not available in the image to improve the quality of the image. It takes unavailable color and replaces it with the closest color available to simulate the actual color. These methods used on Bitmap image are to produce the best possible on screen display possible. Without these methods, images will go haywire. Strange colors and images will appear if things are not compatible with each other resulting in horrible image display.

Scaling Size & Resolution

   A bitmap image can be scale in size and resolution. Scaling the size of the bitmap higher will result in pixilated image which tends to look dither and blurry. This tends to decrease the quality of the image. The reason is that when the size of the bitmap is increase, the computer guess and put generic palette color in place of the missing pixels. This will make the bitmap image look pixilated. Scaling the size of the bitmap smaller will make the pixels in the bitmap to move closer to each other resulting overlap pixels. The resulting image will look small and crush.

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