A bitmapped image is one made from an array of colored points arranged in a grid, rather than continuous lines or areas.
A bitmapped image stores an image in a series of pixels. For instance, if your digital camera takes an 800×600 pixel photograph, the bitmapped version of the image would have one entry for each pixel (800 pixels across, 600 down). When you opened that picture on your computer, the bitmap file would tell your computer what color to display in each pixel location.
Bitmapped image quality can vary immensely based on the number of bits they use to store information. For instance, a 1-bit bitmap can only pick between 2 colors, black or white, for each pixel. To make colored images, higher quality bitmaps need to be used. By using 4 bits of data for every pixel, bitmaps images are able to choose from 16 different color shades (24). That’s a lot better than just having black and white, but still not enough to create truly rich photos with realistic color varieties. Most bitmaps now use between 16 and 48 bits to store the specific shade for each pixel. A 16-bit image can display any of over 65,000 color shades in each pixel. 24-bit images can use over 16 million shades. 48-bit images…well, that an awful lot of color variety!
Frequently Asked Questions
Does the size of a bitmapped image matter?
The quality of a bitmapped image is also dependent on the number of pixels it contains. For instance, the 800 x 600 pixel photograph we mentioned above only stores colors for 480,000 spots on the screen (800 x 600). That may seem like a lot, but most HD televisions have over 2 million pixels, so that 800 x 600 photo is going to have to be stretched to cover the additional space, which can result in blurring or pixilation (jagged edges around digital images). Now imagine if you could select a specific color for all 2 million pixels. The resulting image would provide crisper images with richer detail.
The more pixels a bitmap stores, the more detailed the image will be. Today’s 4K HD screens have nearly 9 million pixels (4,096 x 2,160), making them capable of displaying four times the detail of standard HD.
How are bitmapped images different from jpeg images?
Different file formats store information in different ways. JPEG images are a compressed version of bitmaps. They reduce the size of the image file by removing information about the image which the human eye typically can’t detect. For instance, if you’re looking at an image on a 4k screen, your eye probably won’t notice if some of those 9 million pixels don’t have the exact same tone they had in the bitmap format. Since JPEG files compress the image, they take up far less space on your computer; however, they do so at the loss of overall quality.