Digitizing images

Digitizing images is possible using vector and raster graphics methods. Vector images are created as a collection of lines, vectors, points. Raster images are formed as a set of points (pixels), distributed in rows and columns.

Digitizing images is possible using vector and raster graphics methods

Any color can be represented by a combination of three primary colors, while the color of the mixture depends only on the color of the components. In the RGB model, red (Red), green (Green) and blue (Blue), which are characterized by their brightness, are taken as the main three colors.

When digitizing, the image is projected onto the photosensitive matrix m of rows and n columns, called a raster. Each element of the matrix - the smallest point of the image, consisting of three photosensitive (that registers the brightness) sensors red, green and yellow. Further, the brightness of each point of the image is digitized for each color in succession along all rows of the raster.

If you use one byte (8 bits) for each of the three colors (only 3x8 = 24 bits) to digitize the brightness of each point, the system will provide a representation of 224 = 16,7 million recognizable colors, which close color perception of the human eye. The mode of digitizing images from 24 digits is called True Color. For example, if the screen of the monitor has a raster of 800x600 pixels, the digitization of the image presented in True Color mode will take 800x600x3 = 1440000 bytes.

When digitizing an image, when high quality of display is not required, High Color mode is applied, which encodes one dot of the raster with two bytes (16 bits give 216 = 65,5 thousand colors).

If one byte is used for digitizing images for one point of the raster, then 256 colors are distinguished. This is not enough for a normal perception of human sight.

Thus, images are digitized in devices that emit light - monitors, televisions.

On paper, the image does not emit light waves and is formed on the basis of the reflected wave from the painted surfaces, which must absorb (ie subtract) all the constituent colors, in addition to what we see. For example, if we see a green tree, it means that from the falling white light, i.e. The sums of red, green, blue, are absorbed in red and blue, and green is reflected. The color of the surface can be obtained by dyes that absorb, and do not emit, and should be complementary: blue (Cyan = B + G), complementing red; Purple (Magenta = R + B), complementing the green; yellow (Yellow = R + G), complementing the blue. To increase the contrast is applied even black (blacK). The SMYK model is named after the first letters of the words Cyan, Magenta, Yellow and the last letter of the word blacK.

Tools