imgradientxy
Directional gradients of an image
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Syntax
? [Gx,Gy] = imgradientxy(I)
example
? [Gx,Gy] = imgradientxy(I,method)
example
?
[gpuarrayGx,gpuarrayGy] = imgradientxy(gpuarrayI,___)
example
Description
[Gx,Gy] = imgradientxy(I) returns the directional gradients, Gx and Gy, the
same size as the input image I.
When applying the gradient operator at the boundaries of the image, values outside the bounds of the image are assumed to equal the nearest image border value.
[Gx,Gy] = imgradientxy(I,method) returns the directional gradients using the
specified method.
[gpuarrayGx,gpuarrayGy] = imgradientxy(gpuarrayI,___) performs the operation
on a GPU. The input image and the return values are gpuArrays. This syntax requires the Parallel Computing Toolbox?
Examples
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example
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Calculate directional gradients
Read image.
I = imread('coins.png');
Calculate gradient magnitude and gradient direction using Prewitt's gradient operator
[Gx, Gy] = imgradientxy(I,'prewitt');
figure; imshowpair(Gx, Gy, 'montage');
title('Directional Gradients: x-direction, Gx (left), y-direction, Gy (right), using Prewitt method') axis off;
Calculate directional gradients on a GPU
Read image into a gpuArray.
I = gpuArray(imread('coins.png'));
imshow(I)
Calculate gradient magnitude and gradient direction using Prewitt's gradient operator and display images.
[Gx, Gy] = imgradientxy(I,'prewitt');
figure, imshow(Gx, []), title('Directional gradient: X axis') figure, imshow(Gy, []), title('Directional gradient: Y axis')
Display gradient magnitude and direction in addition to directional gradients
Read image and return directional gradients, Gx and Gx, as well as gradient magnitude and direction, Gmag and Gdir, utilizing default Sobel gradient operator.
I = imread('coins.png'); [Gx, Gy] = imgradientxy(I); [Gmag, Gdir] = imgradient(Gx, Gy);
figure; imshowpair(Gmag, Gdir, 'montage'); axis off;
title('Gradient Magnitude, Gmag (left), and Gradient Direction, Gdir (right), using Sobel method')
figure; imshowpair(Gx, Gy, 'montage'); axis off;
title('Directional Gradients, Gx and Gy, using Sobel method')
Calculate gradient magnitude and direction in addition to directional gradients on a GPU
Read image and return directional gradients, Gx and Gx, as well as gradient magnitude and direction, Gmag and Gdir, utilizing default Sobel gradient operator.
