Negative | COMP101

Pseudocode

PROCEDURE negative(image)
    FOR x = 0 .. width DO
        FOR y = 0 .. height DO
            c <- pixel(x, y)

            FOR i = 0 .. 3 DO
                c`_i <- 255 - c_i
            END FOR

            pixel(x, y) <- c'
        END FOR
    END FOR
END PROCEDURE

Where

The valid range of a channel is 0 .. 255

Description

Loop through all pixels in the image, for each channel in the pixel calculate the new value by subtracting its maximum possible value (255 in the example code) from its current value. Set the pixel to be this newly calculated value.

Acknowledgements

Adapted from Pseudocode produced for COMP120 by Dr. Micheal Scott.