imsubtract (Image Processing Toolbox User's Guide)

Image Processing Toolbox User's Guide

Subtract one image from another, or subtract a constant from an 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. X and Y are real, nonsparse numeric arrays of the same size and class, or Y is a double scalar. The array returned, Z, has the same size and class as X unless X is logical, in which case Z is double.

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

Note On Intel architecture processors, imsubtract can take advantage of the Intel Performance Primitives Library (IPPL), thus accelerating its execution time. IPPL is activated only if array X is of class uint8, int16, or single.

Examples

Subtract two uint8 arrays. Note that negative results are rounded to 0.

X = uint8([ 255 10 75; 44 225 100]);
Y = uint8([ 50 50 50; 50 50 50 ]);
Z = imadd(X,Y)
Z =

   205    0   25
    0   175   50

Estimate and subtract the background of an image:

I = imread('rice.png');
background = imopen(I,strel('disk',15));
Ip = imsubtract(I,background);
imshow(Ip,[])

Subtract a constant value from an image:

I = imread('rice.png');
Iq = imsubtract(I,50);
figure, imshow(I), figure, imshow(Iq)

See Also

imabsdiff, imadd, imcomplement, imdivide, imlincomb, immultiply, ippl

imshow imtool