Crop bounding boxes
[___] = bboxcrop(___,
additionally sets an overlap threshold.
Center Crop Image and Corresponding Bounding Boxes
Read an image.
I = imread('peppers.png');
Define bounding boxes and labels.
bboxA = [ 410 230 100 90 186 78 80 60 ]
bboxA = 2×4 410 230 100 90 186 78 80 60
labelsA = [ "garlic" "onion" ];
Create a center cropping window.
targetSize = [256 256]; win = centerCropWindow2d(size(I),targetSize);
Center crop the image.
[r,c] = deal(win.YLimits(1):win.YLimits(2),win.XLimits(1):win.XLimits(2)); J = I(r,c,:);
Center crop boxes and labels. Boxes outside the cropping window are removed.
[bboxB,indices] = bboxcrop(bboxA,win); labelsB = labelsA(indices);
Display the results.
figure I = insertObjectAnnotation(I,'Rectangle',bboxA,labelsA); J = insertObjectAnnotation(J,'Rectangle',bboxB,labelsB); imshowpair(I,J,'montage')
bboxA — Bounding boxes
M-by-4 matrix | M-by-5 matrix | M-by-9 matrix
Bounding boxes, specified as an M-by-4, M-by-5, or M-by-9 nonsparse numeric matrix. M is the number of bounding boxes. Each row of the matrix defines a bounding box as either an axis-aligned rectangle, a rotated rectangle, or a cuboid. This table describes the format for each bounding box.
Defined in pixel coordinates as an M-by-4 numeric matrix with rows of the form [x y w h], where:
Defined in spatial coordinates as an M-by-5 numeric matrix with rows of the form [xctr yctr xlen ylen yaw], where:
Defined in spatial coordinates as an M-by-9 numeric matrix with rows of the form [xctr yctr zctr xlen ylen zlen xrot yrot zrot], where:
The figure shows how these values determine the position of a cuboid.
window — Crop window
four-element vector (default) |
images.spatialref.Cuboid | numeric | image
threshold — Overlap threshold
1 (default) | positive scalar less than or equal to
Overlap threshold, specified as a positive scalar less than or equal to
1. The amount of overlap between transformed boxes and the area
defined by the output view is defined as:
bbox area intersect bounding rectangle) /bbox area)
bounding rectangle — Defined by the input spatial reference object,
bbox — Result of transforming boxes in
If the computed overlap value is greater than the value of the
threshold property, then the transformed boxes are clipped to the
bounding rectangle border. Otherwise, the boxes are discarded. Lowering the threshold
can result in parts of the object getting discarded.
bboxB — Cropped bounding boxes
M2-by-N matrix | nonsparse numeric
Cropped bounding boxes, returned as an M2-by-N
matrix of M2 bounding boxes. The number of bounding boxes returned is
less than the number of bounding boxes in the input. Each row, M2, of
the matrix defines one bounding box of the same type as the input
indices — Indices
vector of integers
Indices, returned as a vector of integers. The indices indicate which bounding boxes
in the input,
bboxA, are within the cropping window.