imsubtract

Subtract one image from another or subtract constant from image

Syntax

Z = imsubtract(X,Y)

Description

Z = imsubtract(X,Y) subtracts each element in array Y from the corresponding element in array X and returns the difference in the corresponding element of the output array Z.

If X is an integer array, elements of the output that exceed the range of the integer type are truncated, and fractional values are rounded.

Examples

Subtract Two uint8 Arrays

This example shows how to subtract two uint8 arrays. Note that negative results are rounded to 0.

X = uint8([ 255 0 75; 44 225 100]);
Y = uint8([ 50 50 50; 50 50 50 ]);
Z = imsubtract(X,Y)

Z = 2x3 uint8 matrix

   205     0    25
     0   175    50

Subtract Image Background

Read a grayscale image into the workspace.

I = imread('rice.png');

Estimate the background.

background = imopen(I,strel('disk',15));

Subtract the background from the image.

J = imsubtract(I,background);

Display the original image and the processed image.

imshow(I)

figure
imshow(J)

Subtract a Constant from an Image

Read an image into the workspace.

I = imread('rice.png');

Subtract a constant value from the image.

J = imsubtract(I,50);

Display the original image and the result.

imshow(I)

figure
imshow(J)

Input Arguments

X — First array

real, nonsparse, numeric or logical array

First array (minuend), specified as a real, nonsparse, numeric or logical array of any dimension.

Y — Second array

real, nonsparse, numeric or logical array

Second array (subtrahend) to be subtracted from X, specified as a real, nonsparse, numeric or logical array. Y either has the same size and class as X, or Y is a scalar of type double.

Output Arguments

Z — Difference

numeric array

Difference, returned as a numeric array of the same size as X. Z is the same class as X unless X is logical, in which case Z is data type double. If X is an integer array, elements of the output that exceed the range of the integer type are truncated, and fractional values are rounded.