Index Image Work For Free

in the previous video of this series you saw that a bitmap is a rectangular grid of cells called pixels a bitmap image is also known as a raster image there are three fundamental properties of a bitmap image the number of pixels which can be calculated by multiplying the width in pixels by the height in pixels the resolution which depends on the size of the pixels the smaller the pixels the greater the density of pixels so the higher the resolution and the better the quality of the image resolution is measured in dots per inch the color depth that's the number of bits used to encode the color of each pixel more bits per pixel means that more different colors can be used in the image if necessary with 8 bits per pixel a bitmap can have up to 2 to the power 8 that's 256 different colors this 8-bit image looks pretty good but you might have noticed some banding in the sky in the previous video of this series you also saw that we can calculate the amount of memory a bitmap needs by multiplying the number of pixels by the number of bits allocated to each pixel for example a bitmap measuring 960 by 640 pixels with a color depth of 8 bits per pixel will take up 600 kilobytes of memory the simplest type of bitmap is saved to secondary storage as a two-dimensional array of pixel data each and every pixel is given a number to encode its color when the color of each and every pixel in an image is encoded separately it's known as a true color image of course with true color lots of pixels in an image may well have exactly the same color code a small amount of metadata also needs to be saved for the benefit of any software that needs to interpret and display the image this will include the width and height in pixels and the all-important depth so the software knows where the information about one particular pixel begins and where it ends 124 bits are used to encode the color of each pixel there can be as many as 2 to the power 24 that's sixteen point seven million different colors notice that the banding in the sky is no longer visible in this 24-bit RGB image the quality is much better describing the color of each pixel with 24 bits depends on the fundamental principle of light mainly that you can make pretty much any color you need including white by mixing together different amounts of the primary colors red green and blue hence the term RGB if you've ever seen a rainbow in the sky then you've seen white light being split into a spectrum of different colors in essence the opposite effect in fact your computer screen relies on this principle because it's 2 is made up of pixels when magnified each screen pixel can be seen to consist of three tiny lights one red one green and one blue these lights are controlled independently for each screen pixel to create the illusion of a single color in a 24-bit RGB bitmap the amount of red green and blue in each pixel are encoded separately each of these three colors is known as a channel this means you can think of an...