This paper describes an image point arithmetic operation in the pixel level, the principles of the algebraic and logical operations.
Point operations
In the calculation point it can be divided into linear and non-linear point operation point operations
Linear point operation
among them:
a = 0, b = 1 identity;
a <0 black and white inverted;
| A |> 1 increase contrast;
| A | <1 reduce the contrast;
b> 0 increase brightness;
b <0 is reduced brightness;
Nonlinear point operation
C> 0 to increase luminance intermediate portion;
C <0 the luminance reducing an intermediate portion;
Point operation characteristic
point operations for each pixel in a grayscale image, the gradation value changes independent of
the gradation value of each pixel of an output image depends only on the value of the corresponding pixel of the input
point operation does not change the image the spatial relationship
from pixel to pixel operating
point operations may consist entirely or grayscale gradation transformation function mapping table to determine
Algebraic operations
Addition, subtraction, multiplication.
addition
Application: Removal of "overlay" of noise generated image overlay effects.
Subtraction
Application: removing unwanted superposition pattern, detecting change between two images of the same scene.
multiplication
Applications: partial image display, multiply a binary mask image and the original image.
logic operation
Negate
Application: to obtain a negative image of the image, get a child up image of the image.
XOR
Application: get intersect sub-image.
AND operation
Application: find the intersection of the two sub-images subgraph.