Read image into a gpuArray.
I = gpuArray(imread('coins.png')); imshow(I)
Calculate gradient and display images.
[Gx, Gy] = imgradientxy(I); [Gmag, Gdir] = imgradient(Gx, Gy);
figure, imshow(Gmag, []), title('Gradient magnitude') figure, imshow(Gdir, []), title('Gradient direction')
figure, imshow(Gx, []), title('Directional gradient: X axis') figure, imshow(Gy, []), title('Directional gradient: Y axis')
Input Arguments
collapse all
I — Input imagegrayscale image | binary image
Input image, specified as a grayscale or binary image, that is, a numeric or logical 2-D matrix that must be nonsparse, or a gpuArray.
Data Types: single | double | int8 | int32 | uint8 | uint16 | uint32 | logical
gpuarrayI — Input imagegpuArray
Input image, specified as a 2-D grayscale or binary gpuArray image. Data Types: single | double | int8 | int32 | uint8 | uint16 | uint32 | logical
method — Gradient operator‘Sobel' (default) | ‘Prewitt' | 'CentralDifference' | 'IntermediateDifference' Gradient operator, specified as one of the text strings in the following table. Method Description ‘Sobel' Sobel gradient operator (default) ‘Prewitt' Prewitt gradient operator 'CentralDifference', Central difference gradient: dI/dx = (I(x+1)- I(x-1))/2 'IntermediateDifference' Intermediate difference gradient: dI/dx = I(x+1) - I(x) Data Types: char Output Arguments collapse all Gx — Directional gradients along x-axismatrix Directional gradient along the x-axis, returned as non-sparse matrix equal in size to image I. The x-axis points in the direction of increasing column subscripts. The output matrices are of class double, unless the input image is of class single, in which case they are of class single. When the input image I is a gpuArray, Gx is a gpuArray. Data Types: single | double gpuarrayGx — Directional gradients along
x-axisgpuArray
Directional gradient along the x-axis, returned as non-sparse gpuArray equal in size to image I. The x-axis points in the direction of increasing column subscripts. The output matrices are of class double, unless the input image is of class single, in which case they are of class single. Data Types: single | double
Gy — Directional gradient along they-axismatrix
Directional gradients along the y-axis, returned as non-sparse matrix equal in size to image I. The y-axis points in the direction of increasing row subscripts. The output matrices are of class double, unless the input image is of class single, in which case they are of class single. Data Types: single | double
gpuarrayGy — Directional gradient along
they-axisgpuArray
Directional gradients along the y-axis, returned as non-sparse gpuArray equal in size to image I. The y-axis points in the direction of increasing row subscripts. The output matrices are of class double, unless the input image is of class single, in which case they are of class single. Data Types: single | double
