laplacelaplaceLaplaceLaplacelaplace (算子)

名称

laplacelaplaceLaplaceLaplacelaplace — 使用有限差分计算拉普拉斯算子。

签名

描述

laplacelaplaceLaplaceLaplaceLaplacelaplace filters the input images ImageImageImageImageimageimage using a Laplace operator. Depending on the parameter FilterMaskFilterMaskFilterMaskFilterMaskfilterMaskfilter_mask the following approximations of the Laplace operator are used:

'n_4'

1 1 -4 1 1

'n_8'

1 1 1 1 -8 1 1 1 1

'n_8_isotropic'

10 22 10 22 -128 22 10 22 10

For the three filter masks the following normalizations of the resulting gray values is applied, (i.e., by dividing the result by the given divisor): 'n_4'"n_4""n_4""n_4""n_4""n_4" normalization by 1, 'n_8'"n_8""n_8""n_8""n_8""n_8", normalization by 2 and for 'n_8_isotropic'"n_8_isotropic""n_8_isotropic""n_8_isotropic""n_8_isotropic""n_8_isotropic" normalization by 32.

For a Laplace operator with size 3x3, the corresponding filter is applied directly, while for larger filter sizes the input image is first smoothed using a Gaussian filter (see gauss_imagegauss_imageGaussImageGaussImageGaussImagegauss_image) or a binomial filter (see binomial_filterbinomial_filterBinomialFilterBinomialFilterBinomialFilterbinomial_filter) of size MaskSizeMaskSizeMaskSizeMaskSizemaskSizemask_size-2. The Gaussian filter is selected for the above values of ResultTypeResultTypeResultTypeResultTyperesultTyperesult_type. Here, MaskSizeMaskSizeMaskSizeMaskSizemaskSizemask_size = 5, 7, 9, 11, or 13 must be used. The binomial filter is selected by appending '_binomial'"_binomial""_binomial""_binomial""_binomial""_binomial" to the above values of ResultTypeResultTypeResultTypeResultTyperesultTyperesult_type. Here, MaskSizeMaskSizeMaskSizeMaskSizemaskSizemask_size can be selected between 5 and 39. Furthermore, it is possible to select different amounts of smoothing for the column and row direction by passing two values in MaskSizeMaskSizeMaskSizeMaskSizemaskSizemask_size. Here, the first value of MaskSizeMaskSizeMaskSizeMaskSizemaskSizemask_size corresponds to the mask width (smoothing in the column direction), while the second value corresponds to the mask height (smoothing in the row direction) of the binomial filter. Therefore, for MaskSizeMaskSizeMaskSizeMaskSizemaskSizemask_size > 3 is equivalent to and is equivalent to

laplacelaplaceLaplaceLaplaceLaplacelaplace either returns the absolute value of the Laplace filtered image (ResultTypeResultTypeResultTypeResultTyperesultTyperesult_type = 'absolute'"absolute""absolute""absolute""absolute""absolute") in a byte or uint2 image or the signed result (ResultTypeResultTypeResultTypeResultTyperesultTyperesult_type = 'signed'"signed""signed""signed""signed""signed" or 'signed_clipped'"signed_clipped""signed_clipped""signed_clipped""signed_clipped""signed_clipped"). Here, the output image type has the same number of bytes per pixel as the input image (i.e., int1 or int2) for 'signed_clipped'"signed_clipped""signed_clipped""signed_clipped""signed_clipped""signed_clipped", while the output image has the next larger number of pixels (i.e., int2 or int4) for 'signed'"signed""signed""signed""signed""signed".

注意

请注意，若使用域缩减后的图像作为输入，滤波器算子可能会返回意外结果。请参阅 滤波器 一章

执行信息

• 多线程类型：可重入（与非独占算子并行运行）。
• 多线程作用域：全局（可从任何线程调用）。
• 在元组级别上自动并行化。
• 在通道级别上自动并行化。
• 在域级别上自动并行化。

参数

示例（C）

read_image(&Image,"mreut");
laplace(Image,&Laplace,"signed",3,"n_8_isotropic");
zero_crossing(Laplace,&ZeroCrossings);

结果

laplacelaplaceLaplaceLaplaceLaplacelaplace 在所有参数正确时返回 2 ( H_MSG_TRUE )。 如果输入为空则可设置行为通过 set_system('no_object_result',<Result>)set_system("no_object_result",<Result>)SetSystem("no_object_result",<Result>)SetSystem("no_object_result",<Result>)SetSystem("no_object_result",<Result>)set_system("no_object_result",<Result>)。如有必要，则抛出异常。

可能的后继

zero_crossingzero_crossingZeroCrossingZeroCrossingZeroCrossingzero_crossing, dual_thresholddual_thresholdDualThresholdDualThresholdDualThresholddual_threshold, thresholdthresholdThresholdThresholdThresholdthreshold

替代

diff_of_gaussdiff_of_gaussDiffOfGaussDiffOfGaussDiffOfGaussdiff_of_gauss, laplace_of_gausslaplace_of_gaussLaplaceOfGaussLaplaceOfGaussLaplaceOfGausslaplace_of_gauss, derivate_gaussderivate_gaussDerivateGaussDerivateGaussDerivateGaussderivate_gauss

另见

highpass_imagehighpass_imageHighpassImageHighpassImageHighpassImagehighpass_image, edges_imageedges_imageEdgesImageEdgesImageEdgesImageedges_image

模块

基础

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