Understanding image file sizes
Each pixel in a raster image typically takes up about 1 to 8 bits for black-and-white images and 8 to 64 bits for colored images. And the more pixels an image has, the more data it stores and the larger its file size.
8-bit
Well, a JPEG is an 8-bit image, which means that it uses 8 bits per color channel. pulvinar dapibus leo.
Each pixel typically consists of 8 bits (1 byte) for a Black and White (B&W) image or 24 bits (3 bytes) for a color image– one byte each for Red, Green, and Blue.
A color image is typically represented by a bit depth ranging from 8 to 24 or higher. With a 24-bit image, the bits are often divided into three groupings: 8 for red, 8 for green, and 8 for blue. Combinations of those bits are used to represent other colors. A 24-bit image offers 16.7 million (2 24 ) color values.
File sizes are always measured in bytes. A byte is a sequence of 8 bits (and remember, a bit is the smallest piece of digital information, or ). A single byte is enough bits to represent 256 numbers, because 2 8 = 256 .
As with RGB and gray+alpha, PNG supports 8 and 16 bits per sample for RGBA or 32 and 64 bits per pixel, respectively.
If the pixel dimensions are given, multiply them by each other and the bit depth to determine the number of bits in an image file. For instance, if a 24-bit image is captured with a digital camera with pixel dimensions of 2,048 x 3,072, then the file size equals (2048 x 3072 x 24)/8, or 18,874,368 bytes.
