adaptthresh() - Image Processing

T = adaptthresh(I) computes a locally adaptive threshold that can be used with the imbinarize function to convert an intensity image to a binary image.
The result, T, is a matrix the same size as I containing normalized intensity values in the range [0, 1].
adaptthresh chooses the threshold based on the local mean intensity (first-order statistics) in the neighborhood of each pixel.
T = adaptthresh(I,sensitivity) computes a locally adaptive threshold with sensitivity factor specified by sensitivity. sensitivity is a scalar in the range [0 1] that indicates sensitivity towards thresholding more pixels as foreground.
T = adaptthresh(___,Name,Value) computes a locally adaptive threshold using name-value pairs to control aspects of the thresholding.
Code Generation support: Yes.
MATLAB Function Block support: Yes.

Syntax

T = adaptthresh(I) 
T = adaptthresh(I,sensitivity) 
T = adaptthresh(___,Name,Value) 

Example

%Find Threshold and Segment Bright Rice Grains from Dark BackgroundOpen 
%This Example Read image into the workspace.
I = imread('rice.png');
%Use adaptthresh to determine threshold to use in binarization operation.
T = adaptthresh(I, 0.4);
%Convert image to binary image, specifying the threshold value.
BW = imbinarize(I,T);
%Display the original image with the binary version, side-by-side.
figure
imshowpair(I, BW, 'montage')

%Find Threshold and Segment Dark Text from Bright Background Read image into the workspace.
I = imread('printedtext.png');
%Using adaptthresh compute adaptive threshold and display the local threshold image. This represents an estimate of average background illumination.
T = adaptthresh(I,0.4,'ForegroundPolarity','dark');
figure
imshow(T)

%Binarize image using locally adaptive threshold
BW = imbinarize(I,T);
figure
imshow(BW)

Output / Return Value

Limitations

Alternatives / See Also

Reference