Bitmap facts for kids

A bitmap is like a digital painting made of tiny colored squares. Each of these squares is called a pixel. When you look at a photo on your computer, phone, or TV, you are usually seeing a bitmap image. These images are very common and are used for almost all the photos and detailed pictures you see online and in apps.

What is a Bitmap Image?

A bitmap image is a type of raster graphics image. Think of it like a giant grid or a checkerboard. Each square on this grid is a single pixel, and each pixel has its own specific color. When all these tiny colored pixels are put together, they form a complete picture. The word "bitmap" comes from "bit" (the smallest piece of information a computer understands) and "map" (like a map of colors).

How Do Computers Store Bitmap Images?

Computers store information about each pixel in a bitmap image. For a simple black and white image, each pixel might just be a "1" for black or a "0" for white. For colored images, each pixel needs more information to describe its exact color. This information is stored as a series of bits. The more pixels an image has, and the more colors each pixel can show, the larger the file size of the image will be. This is why high-quality photos take up more space than simple drawings.

Bitmap vs. Vector Graphics: What's the Difference?

It's helpful to know that not all digital images are bitmaps. Another type is called vector graphics.

• Bitmap images are made of pixels. When you zoom in a lot on a bitmap, you might start to see the individual pixels, making the image look "blocky" or "pixelated." This is because the computer is just stretching those fixed-size pixels.
• Vector graphics are made of mathematical formulas that describe lines, curves, and shapes. When you zoom in on a vector image, it stays perfectly smooth and clear, no matter how much you zoom. This is because the computer recalculates the shapes based on the formulas. Logos and illustrations are often vector graphics.

Where Do We See Bitmap Images?

Bitmap images are everywhere!

• Digital Photos: Every photo you take with a digital camera or phone is a bitmap image.
• Web Graphics: Most images you see on websites, like JPEGs (for photos), PNGs (for images with transparent backgrounds), and GIFs (for simple animations), are bitmap formats.
• Scanned Documents: When you scan a drawing or document, it turns into a bitmap image.
• Video Games: Many textures and images in video games are bitmaps.

Other Meanings of "Bitmap"

While "bitmap" most often refers to images, the term can also have a few other meanings in computer science:

• Bit Array: Sometimes, "bitmap" can mean a collection of bits that all have a similar purpose. This is also known as a bit array. It's like a list where each item is either "on" (1) or "off" (0).
• BMP File Format: "Bitmap" can also be a shorter way to say BMP file format. This is a specific type of file that stores bitmap images, especially on Windows computers.
• Music Group: There's even a music group from England called Bitmap (group)!