Image Processing Toolbox User's Guide

im2bw

Convert an image to a binary image, based on threshold

Syntax

• BW = im2bw(I,level)
  BW = im2bw(X,map,level)
  BW = im2bw(RGB,level)
  

Description

im2bw produces binary images from indexed, intensity, or RGB images. To do this, it converts the input image to grayscale format (if it is not already an intensity image), and then uses thresholding to convert this grayscale image to binary. The output binary image BW has values of 1 (white) for all pixels in the input image with luminance greater than level and 0 (black) for all other pixels. (Note that you specify level in the range [0,1], regardless of the class of the input image.)

BW = im2bw(I,level) converts the intensity image I to black and white.

BW = im2bw(X,map,level) converts the indexed image X with colormap map to black and white.

BW = im2bw(RGB,level) converts the RGB image RGB to black and white.

Note    The function graythresh can be used to compute the level argument automatically.

Class Support

The input image can be of class uint8, uint16, single, int16, or double, and must be nonsparse. The output image BW is of class logical.

Example

• load trees
  BW = im2bw(X,map,0.4);
  imshow(X,map), figure, imshow(BW)
  
  
  

See Also

graythresh, ind2gray, rgb2gray

ifftn

im2col

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