bwareafilt
Extract objects from binary image by size
Syntax
Description
Examples
Filter Binary Image by Area of Objects
Read image.
BW = imread('text.png');Filter image, retaining only those objects with areas between 40 and 50.
BW2 = bwareafilt(BW,[40 50]);
Display the original image and filtered image side by side.
imshowpair(BW,BW2,'montage')
Filter Binary Image by Size of Objects
Read image.
BW = imread('text.png');Filter image, retaining only the 5 objects with the largest areas.
BW2 = bwareafilt(BW,5);
Display the original image and the filtered image side by side.
imshowpair(BW,BW2,'montage')
Input Arguments
BW — Image to be filtered
binary image
Image to be filtered, specified as a binary image.
Data Types: logical
range — Minimum and maximum areas
2-by-1 numeric vector
Minimum and maximum values of the area, specified as a 2-by-1 numeric
vector of the form [low high].
Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64
n — Number of objects to include
numeric scalar
Number of objects to include when filtering image objects by size, specified as a numeric scalar.
Data Types: double
keep — Size of objects to include
'largest' (default) | 'smallest'
Size of objects to include in the output image, specified as
'largest' or 'smallest'. In the
event of a tie for n-th place,
bwareafilt includes only the first
n objects.
Data Types: char | string
conn — Pixel connectivity
8 (default) | 4 | 3-by-3 matrix of 0s and 1s
Pixel connectivity, specified as one of these values.
Value | Meaning | |
|---|---|---|
Two-Dimensional Connectivities | ||
4-connected | Pixels are connected if their edges touch. Two adjoining pixels are part of the same object if they are both on and are connected along the horizontal or vertical direction. |
|
8-connected | Pixels are connected if their edges or corners touch. Two adjoining pixels are part of the same object if they are both on and are connected along the horizontal, vertical, or diagonal direction. |
|
Connectivity can also be defined in a more general way by
specifying a 3-by-3 matrix of 0s and
1s. The 1-valued elements define
neighborhood locations relative to the center element of
conn. The matrix must be symmetric about its center
element.
Data Types: double | logical
Output Arguments
See Also
bwareaopen | bwconncomp | bwpropfilt | conndef | regionprops