Function sobel

pub fn sobel(
    src: &impl GMatTraitConst,
    ddepth: i32,
    dx: i32,
    dy: i32,
    ksize: i32,
    scale: f64,
    delta: f64,
    border_type: i32,
    border_value: Scalar,
) -> Result<GMat>

Calculates the first, second, third, or mixed image derivatives using an extended Sobel operator.

In all cases except one, the separable kernel is used to calculate the derivative. When , the or kernel is used (that is, no Gaussian smoothing is done). ksize = 1 can only be used for the first or the second x- or y- derivatives.

There is also the special value ksize = FILTER_SCHARR (-1) that corresponds to the Scharr filter that may give more accurate results than the Sobel. The Scharr aperture is

for the x-derivative, or transposed for the y-derivative.

The function calculates an image derivative by convolving the image with the appropriate kernel:

The Sobel operators combine Gaussian smoothing and differentiation, so the result is more or less resistant to the noise. Most often, the function is called with ( xorder = 1, yorder = 0, ksize = 3) or ( xorder = 0, yorder = 1, ksize = 3) to calculate the first x- or y- image derivative. The first case corresponds to a kernel of:

The second case corresponds to a kernel of:

Note:

• Rounding to nearest even is procedeed if hardware supports it, if not - to nearest.
• Function textual ID is “org.opencv.imgproc.filters.sobel”

Parameters

• src: input image.
• ddepth: output image depth, see [filter_depths] “combinations”; in the case of 8-bit input images it will result in truncated derivatives.
• dx: order of the derivative x.
• dy: order of the derivative y.
• ksize: size of the extended Sobel kernel; it must be odd.
• scale: optional scale factor for the computed derivative values; by default, no scaling is applied (see cv::getDerivKernels for details).
• delta: optional delta value that is added to the results prior to storing them in dst.
• borderType: pixel extrapolation method, see cv::BorderTypes
• borderValue: border value in case of constant border type

See also

filter2D, gaussianBlur, cartToPolar

C++ default parameters

• ksize: 3
• scale: 1
• delta: 0
• border_type: BORDER_DEFAULT
• border_value: Scalar(0)