Arithmetic and Logic

Reasons you may use arithmetic and logic are:

to emphasize differences between images by subtracting the pixels (a conformity check).
to compensate for non-uniform lighting by dividing the target image by the image of the background alone.
to remove unwanted areas of an image by preparing an appropriate mask, and clearing all the pixels that belong to the mask by using logical combinations of pixels.
to create a combined image by combining the pixels of two source images to generate a resulting image.

Arithmetic operations are handled by the Oper function, EArithmeticLogicOperation enum lists all supported operators.

These operations can be applied to images and constants, they have one or two source arguments (image or integer constants) and one destination argument. If the source operands are a color and a gray-level image, each color component combines with the gray-level component to give a color image. Histogram equalization can improve your results.

Arithmetic and logic combinations

Allowed combinations

	General	Copy	Invert	Shift	Logical	Overlay	Set
Const BW8 -> Image BW8		x
Const C24 -> Image C24		x
Image BW8 -> Image BW8		x	x
Image BW8 -> Image C24		x	x			x
Image C24 -> Image C24		x	x
Const BW8, Image BW8 -> Image BW8	x
Image BW8, Const BW8 -> Image BW8	x			x			x
Image BW8, Image BW8 -> Image BW8	x				x		x
Image BW8, Image BW8 -> Image C24	x					x
Const C24, Image C24 -> Image C24	x
Image C24, Const C24 -> Image C24	x			x
Image C24, Image C24 -> Image C24	x				x
Image C24, Image BW8 -> Image C24	x				x	x
Image BW8, Image C24 -> Image C24	x				x		x

Note: For logical operators, a pixel with value 0 is assumed FALSE, otherwise TRUE. The result of a logical operation is 0 when FALSE and 255 otherwise.

The classification of operations in the above table are: