imsubtract (Image Processing Toolbox)

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.

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.

If X and Y are double arrays, then you can use the expression X-Y instead of this function.

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 the rice image:

I = imread('rice.tif');
blocks = blkproc(I,[32 32],'min(x(:))');
background = imresize(blocks,[256 256],'bilinear');
Ip = imsubtract(I,background);
imshow(Ip,[])

Subtract a constant value from the rice image:

I = imread('rice.tif');
Iq = imsubtract(I,50);
subplot(1,2,1), imshow(I)
subplot(1,2,2), imshow(Iq)

imshow imtophat