# Documentation

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# 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`.

If `X` and `Y` are real numeric arrays with the same size and class, then `Z` has the same size and class as `X`. If `X` is a numeric array and `Y` is a scalar double, then `Z` has the same size and class as `X`.

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

`immultiply` computes each element of `Z` individually in double-precision floating point. If `X` 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. Note how the example converts the class of the image from `uint8` to `uint16` before performing the multiplication to avoid truncating the results.

```I = imread('moon.tif'); I16 = uint16(I); J = immultiply(I16,I16); imshow(I), figure, imshow(J)```

Scale an image by a constant factor:

```I = imread('moon.tif'); J = immultiply(I,0.5); subplot(1,2,1), imshow(I) subplot(1,2,2), imshow(J)```

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