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What is a Bitmap Image?

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  • Written By: R. Kayne
  • Edited By: Niki Foster
  • Last Modified Date: 18 March 2014
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    Conjecture Corporation
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A bitmap is one of many types of file formats for images stored in a computerized form. It carries the extension .BMP. Computers use bits of 1 and 0 to store data. A bitmap is literally a map of bits that form a particular picture when rendered to a display like a computer monitor.

To understand how a bitmap image displays, it’s important to understand the computer display screen. The display is made up of rows and columns of tiny blocks, or pixels. In a bitmap image, each pixel is assigned at least one bit to indicate whether the pixel should reflect the background color, the foreground color, or some other color.

In the case of a page of black and white text, let’s consider a single letter. The many pixels that make up that letter only require one bit of data each. Either the pixel will be black or white: 1 or 0.

When a bitmap displays a colored image, such as a lake scene, there are several shades of gradation in colors and lighting. In this case, each pixel in the bitmap might have 16, 24, or 48 bits of information associated with it. The more bits, the greater the resolution of the bitmap – and the larger the file.

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Because bitmaps store so much information in the highest resolutions, they make very beautiful images. However, a bitmap image doesn’t rescale well. If blown up using a graphics program, the bitmap image becomes blocky and blurred. If reduced, it loses clarity.

Compression techniques are used to shrink the file size of the bitmap while maintaining as much data as is necessary to render a good picture. One such format is the 8-bit .GIF format, which uses a pallette of 256 colors. The advantage of the compressed .GIF is that it is a smaller file that can be resized with satisfactory results, as it uses lossless compression. The disadvantage is that it cannot faithfully reproduce images containing more than 256 colors.

Photographs saved in the bitmap format that need to be reduced for Internet use can be converted to the JPEG (JAY-peg) format. While this is a lossy compression format, it is capable of displaying more than 256 colors and does a better job of rendering photographs.

Because bitmap images are built pixel-by-pixel, they can be easily edited. Zooming in on a bitmap image in any graphics program allows the user to add, delete, or change the color of individual pixels. For this reason, logos, favicons, and icon images are frequently built in the bitmap format.

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Discuss this Article

anon234025
Post 24

I am not computer savey. Why did my computer put up a icon on my screen, new bitmap image?

anon205851
Post 23

How can I use this if my computer has a virus?

anon143224
Post 21

I have Bitmap photos stored in my computer. What company can print them for me? Walgreens can't.

anon68725
Post 18

what are the features of a bitmap image changes during image embedding?

anon38202
Post 8

How do you convert a pdf file to bitmap

anon38201
Post 7

what is the difference between bitmap and pdf

abbabeta
Post 6

how can i compare a line with a curve on the basis of pixel or bitmap..thanks for your response.

karanshah
Post 5

How do you convert files made in linux to be able to be read in windows?

anon23182
Post 4

how do you make vector graphics?

anon17708
Post 3

What is the best type of file i should use to save images to be included in powerpoint?

anon10497
Post 2

Can i use Bitmap image in text mode?

I want to paste a small bitmap image on screen with full of text.

anon8179
Post 1

How do I use this to send pictures from my phone to my computer?

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