MATLAB: How to crop license plate image automatically

draw rectangleimage cropImage Processing Toolboxlicense platelpr

1.How to crop the attached license plate image automatically? 2.And using these coordinates how to draw red rectangle around license plate in original image?

Best Answer

Get the bounding box with regionprops. Put up rectangle with rectangle. Crop with imcrop().

binaryImage = maskedImage > 0;
labeledImage = bwlabel(binaryImage);
measurements = regionprops(labeledImage, 'BoundingBox');
bb = [measurements.BoundingBox];
% Put up red rectangle
hold on;
rectangle('Position', bb, 'EdgeColor', 'r');
% Crop
croppedImage = imcrop(maskedImage, bb);

Related Solutions

MATLAB: Is the centroid giving only 1 element per blob using region props

It's not clear exactly what you're calling an "element". I'll use more precise terminology. If your Iregion structure array is just one structure, then you have just one blob. The Centroid field of that structure will be a 1-by-2 array with the x and y locations of the centroid of that blob.

If you have multiple blobs, then you need to add an index after the structure variable name to get just one of the blobs, try this:

props = regionprops(bw2,'centroid');
hold on;
for k = 1 : length(props)
    % Get x and y centroid of the k'th blob.
    xCentroid = props(k).Centroid(1);
    yCentroid = props(k).Centroid(2);
    plot(xCentroid, yCentroid, 'r+', 'MarkerSize', 40, 'LineWidth', 2);
    % Let user know what they are
    message = sprintf('The largest blob has area %d and a centroid at (x,y) = (%f, %f)',...
  props.Area, xCentroid, yCentroid)
    uiwait(msgbox(message));
end

You can also get all the x and y centroids into arrays doing this:

centroids = [props.Centroid];
xCentroids = centroids(1:2:end);
yCentroids = centroids(2:2:end);

MATLAB: How to circle the pores in a fingerprint image

Use bwareaopen() to remove larger blobs. Then use regionprops on the remaining small blobs

binaryImage = binaryImage = bwareaopen(binaryImage, 100);
labeledImage = bwlabel(binaryImage);
measurements = regionprops(labeledImage, 'Area', 'Centroid');
allAreas = [measurements.Area];

Best Answer

Related Solutions

MATLAB: Is the centroid giving only 1 element per blob using region props

MATLAB: How to circle the pores in a fingerprint image

Related Question