So far we were concentrated on rendering of
geometric data - points, lines, and polygons.
Now we learn how to read pixel data (bitmaps and images) from the framebuffer into processor memory (and vice versa).
Bitmaps, typically used for characters in fonts.
Image data, which might have been scanned in or calculated.
Both bitmaps and image data take the form of rectangular arrays of pixels. One difference between them is that a bitmap consists of a single bit of information about each pixel, and image data typically includes several pieces of data per pixel (the complete red, green, blue, and alpha color components, for example).