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randomWindow2d

Randomly select rectangular region in image

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Syntax

win = randomWindow2d(inputSize,targetSize)
win = randomWindow2d(inputSize,'Scale',scale,'DimensionRatio',dimensionRatio)

Description

example

win= randomWindow2d(inputSize,targetSize)selects a rectangular region of sizetargetSizefrom a random position in an image of sizeinputSize.

example

win= randomWindow2d(inputSize,'Scale',scale,'DimensionRatio',dimensionRatio)selects a rectangular region, specifying the size of the region relative to the input image,scale, and the aspect ratio of the region,dimensionRatio.

Examples

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Open Live Script

Read and display an image.

I = imread("flamingos.jpg"); imshow(I)

Figure contains an axes object. The axes object contains an object of type image.

Specify the size of the input image and the target size of the rectangular region.

inputSize = size(I); targetSize = [40 60];

Select a region of the target size from a random location in the image.

rect = randomWindow2d(inputSize,targetSize);

Convert the region from aRectangleobject to a 4-element vector of the form [xmin ymin width height].

rectXYWH = [rect.XLimits(1) rect.YLimits(1)...diff(rect.XLimits)+1 diff(rect.YLimits)+1];

Display the boundary of the rectangular region overlaid on the original image.

annotatedI = insertShape(I,"Rectangle",rectXYWH,"LineWidth",3); imshow(annotatedI)

Figure contains an axes object. The axes object contains an object of type image.

Open Live Script

Read and display an image.

I = imread("strawberries.jpg"); imshow(I)

Figure contains an axes object. The axes object contains an object of type image.

Specify the size of the input image.

inputSize = size(I);

Specify a fractional area of the region between 2% and 13% of the area of the input image. Specify a range of aspect ratios between 1:5 and 4:3.

scale = [0.02 0.13]; dimensionRatio = [1 5;4 3];

Specify a region with a randomly selected fractional area and aspect ratio from a random location in the image.

rect = randomWindow2d(inputSize,"Scale",scale,"DimensionRatio",dimensionRatio);

Crop the original image to the randomly selected region and display the result.

Icrop = imcrop(I,rect); imshow(Icrop)

Figure contains an axes object. The axes object contains an object of type image.

Input Arguments

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Input image size, specified as one of the following.

Type of Input Image Format ofinputSize
2-D grayscale or binary image 2-element vector of positive integers of the form[height width]
2-D RGB or multispectral image 3-element vector of positive integers of the form[height width channels]

Target image size, specified as one of the following.

Type of Target Image Format oftargetSize
2-D grayscale or binary image 2-element vector of positive integers of the form[height width]
2-D RGB or multispectral image 3-element vector of positive integers of the form[height width channels]

Region area as a fraction of the input image area, specified as one of these values.

  • 2-element nondecreasing numeric vector with values in the range [0, 1]. The elements define a minimum and maximum fractional area of the region, respectively.randomWindow2d选择一个随机值范围内使用the fractional region area. To use a fixed region area, specify the same value for both elements.

  • Function handle. The function must take no input arguments and return one number in the range [0, 1] specifying a valid fractional region area. For more information about function handles, seeCreate Function Handle.

Range of aspect ratios of the rectangular region, specified as one of these values.

  • 2-by-2 matrix of positive numbers. The first row defines the defines the minimum aspect ratio and the second row defines the maximum aspect ratio.randomWindow2d选择一个随机值范围内使用the aspect ratio. To use a fixed aspect ratio, specify identical values for the first and second rows.

  • Function handle. The function must take no input arguments and return one positive number specifying a valid dimension ratio. For example, a value of1.2specifies a 5:4 aspect ratio. For more information about function handles, seeCreate Function Handle.

Example:[1 8;1 4]selects an aspect ratio in the range 1:8 to 1:4

Output Arguments

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Rectangular window, returned as aRectangleobject.

版本历史

Introduced in R2021a

See Also

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