I'm not sure.Īnd do you remember that knock pattern (dum-da-da-dum-dum, dum dum)? The words to that are 'Shave and a haircut, two bits' That must have been awhile ago because I certainly can't get a haircut these days for 25 cents. so there might be some relationship there to the Spanish bits. In computers there are eight bits in a byte. Massachusetts was the first colony to defy the mother country. Because there was no one-bit coin, a dime (10c) was sometimes called a short bit and 15c a long bit.Įven the New York Stock Exchange continued to list stock prices in eighths of a dollar until J(at which time it started listing in sixteenths, but later going to decimals in 2001). From this, we have the expression 'two bits,' meaning a quarter of a dollar. Thus, twenty-five cents was dubbed 'two bits,' as it was a quarter of a Spanish dollar. Spanish dollars were deemed equivalent in value to a U.S. The term persists colloquially in the United States as a holdover from colonial America when Spanish dollars minted in Mexico, Bolivia and other Spanish colonies were the widest circulating coin. The origin of bit comes from the practice of cutting the Spanish dollar (peso) into eight radial pieces to make change. In sequence that means they are describing 25 cents, 50 cents, 75 cents, a dollar. Now in the formula, if you are given the size of image and the bits per pixel, you can also calculate the rows and columns of the image, provided the image is square(same rows and same column).You can figure that out from context too. Thats how an image size is calculated and it is stored. Then putting these values in the formula, we getīut since its not a standard answer that we recognize, so will convert it into our format.Ĭonverting it into bytes = 8388608 / 8 = 1048576 bytes.Ĭonverting into kilo bytes = 1048576 / 1024 = 1024kb.Ĭonverting into Mega bytes = 1024 / 1024 = 1 Mb.

And since it is a gray scale image, it has 256 different shades of gray or it has bits per pixel. It means that if you have an image, lets say this one:Īssuming it has 1024 rows and it has 1024 columns. The formula for calculating the size is given below. The size of an image depends upon three things. Image storage requirementsĪfter the discussion of bits per pixel, now we have every thing that we need to calculate a size of an image. In case of 8bpp, the pixel value that denotes gray color is 127 or 128bpp (if you count from 1, not from 0). Gray color is actually the mid point of black and white. When you calculate the black and white color value, then you can calculate the pixel value of gray color. In case 8 bpp, 0 denotes black, and 255 denotes white. In case of 1 bpp, 0 denotes black, and 1 denotes white. The value that denotes white color can be calculated as : But there is no fixed value that denotes white color. Remember, 0 pixel value always denotes black color. We have previously seen in the tutorial of concept of pixel, that 0 pixel value denotes black color. We will see more about other color formats and image types in the tutorial of image types. The famous gray scale image is of 8 bpp, means it has 256 different colors in it or 256 shades.Ĭolor images are usually of the 24 bpp format, or 16 bpp. You can easily notice the pattern of the exponentional growth. This table shows different bits per pixel and the amount of color they contain. The table for some of the bits and their color is given below. Now as we said it in the beginning, that the number of different colors depend on the number of bits per pixel. Put 1 in the formula you get 2, put 2 in the formula, you get 4.

If we devise a formula for the calculation of total number of combinations that can be made from bit, it would be like this. How many two bits combinations can be made. How many numbers can be represented by one bit. The number of different colors in an image is depends on the depth of color or bits per pixel. Bpp or bits per pixel denotes the number of bits per pixel.

Two bits meaning