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Convert connected components to binary image

Since R2024a



    BW = cc2bw(CC) creates a binary image from the connected components (objects) in CC.


    BW = cc2bw(CC,ObjectsToKeep=objectsToKeep) creates a binary image from a subset of connected components, specified by objectsToKeep.


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    Read and display an image.

    I = imread("blobs.png");

    Create a connected components structure.

    CC = bwconncomp(I);

    Filter the structure and keep round objects. Display the filtered image.

    CC = bwpropfilt(CC,"Circularity",[0.7 1]);

    Filter the structure again and keep large objects. Display the filtered image.

    CC = bwpropfilt(CC,"Area",[20 Inf]);

    Read a binary image and detect the connected components.

    BW = imread("text.png");
    CC = bwconncomp(BW);

    Measure the area of each connected component and return the results as a table.

    p = regionprops("table",CC,"Area");

    Create a binary image that contains only the 2nd through 10th largest connected components. Display the result.

    [~,idx] = sort(p.Area,"descend");
    BWfilt = cc2bw(CC,ObjectsToKeep=idx(2:10));

    Read a grayscale image of grains of rice, then convert the image to binary.

    I = imread("rice.png");
    BW = imbinarize(I);

    Measure the area and bounding box of each region.

    CC = bwconncomp(BW); 
    stats = regionprops("table",CC,"Area","BoundingBox");

    Select regions for whom these conditions apply:

    • The area is greater than 50 pixels

    • The bounding box is less than 15 pixels wide and is greater than or equal to 20 pixels tall.

    area = stats.Area;
    bbox = stats.BoundingBox;
    selection = (area > 50) & (bbox(:,3) < 15) & (bbox(:,4) >= 20);
    BW2 = cc2bw(CC,ObjectsToKeep=selection);

    Display the filtered image.


    Input Arguments

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    Connected components (objects), specified as a structure with four fields.

    ConnectivityConnectivity of the connected components
    ImageSizeSize of the binary image
    NumObjectsNumber of connected components in the binary image.
    PixelIdxList1-by-NumObjects cell array where the k-th element in the cell array is a vector containing the linear indices of the pixels in the k-th object.

    Objects to keep, specified as one of these values.

    • Positive integer or vector of positive integers — Keep the object or objects whose index is included in objectsToKeep. The length of objectsToKeep is less than or equal to CC.NumObjects.

    • Logical vector — Keep the objects whose corresponding element in objectsToKeep is true. The length of objectsToKeep must be equal to CC.NumObjects.

    Output Arguments

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    Binary image, returned as a logical array of the same size as CC.ImageSize.

    Data Types: logical

    Extended Capabilities

    Version History

    Introduced in R2024a

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