immultiply

Multiply two images or multiply image by constant

Syntax

Z = immultiply(X,Y)

Description

Z = immultiply(X,Y) multiplies each element in array X by the corresponding element in array Y and returns the product in the corresponding element of the output array Z.

immultiply computes each element of Z individually in double-precision floating point. If X or Y is an integer array, then elements of Z exceeding the range of the integer type are truncated, and fractional values are rounded.

If X and Y are numeric arrays of the same size and class, you can use the expression X.*Y instead of immultiply.

Examples

Multiply an Image by Itself

Read a grayscale image into the workspace, then convert the image to uint8.

I = imread('moon.tif');
I16 = uint16(I);

Multiply the image by itself. Note that immultiply converts the class of the image from uint8 to uint16 before performing the multiplication to avoid truncating the results.

J = immultiply(I16,I16);

Show the original image and the processed image.

imshow(I)

figure
imshow(J)

Scale an Image by a Constant Factor

Read an image into the workspace.

I = imread('moon.tif');

Scale each value of the image by a constant factor of 0.5.

J = immultiply(I,0.5);

Display the original image and the processed image.

imshow(I)

figure
imshow(J)

Input Arguments

X — First array

real, nonsparse, numeric or logical array

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

Y — Second array

real, nonsparse, numeric or logical array

Second array to be multiplied with X, specified as a real, nonsparse, numeric or logical array.

• If X is numeric, then the size and class of Y can have one of the following values:

  • Y is the same size and class as X.

  • Y is the same size as X and is logical.

  • Y is a scalar of type double.

• If X is logical, then Y must have the same size as X. Y can be any class.

Output Arguments

Z — Product

numeric array

Product, returned as a numeric array.

• If X is numeric, then Z has the same size and class as X.

• If X is logical, then Z has the same size and class as Y.

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