Area of objects in binary image
Calculate Area of Objects in Binary Image
Read a binary image and display it.
BW = imread('circles.png'); imshow(BW)
Calculate the area of objects in the image.
ans = 1.4187e+04
BW — Binary image
2-D numeric matrix | 2-D logical matrix
Binary image, specified as a 2-D numeric or logical matrix.
BW = imread('text.png'); L =
bwarea estimates the area of all of the
pixels in an image by summing the areas of each pixel in the image. The area of an
individual pixel is determined by looking at its 2-by-2 neighborhood. There are six
different patterns, each representing a different area:
Patterns with zero
onpixels (area = 0)
Patterns with one
onpixel (area = 1/4)
Patterns with two adjacent
onpixels (area = 1/2)
Patterns with two diagonal
onpixels (area = 3/4)
Patterns with three
onpixels (area = 7/8)
Patterns with all four
onpixels (area = 1)
Each pixel is part of four different 2-by-2 neighborhoods. This means, for example,
that a single
on pixel surrounded by
has a total area of 1.
 Pratt, William K., Digital Image Processing, New York, John Wiley & Sons, Inc., 1991, p. 634.