opencv中cvFilter2D( ) 函数filter2D（）函数与MATLAB中imfilter（）函数的差异

出处：

1:cvFilter2D() 函数为opencv中c语言函数

2：filter2D()函数为opencv中c++函数

3：imfilter()函数为matlab版本函数

计算结果的异同：

2（c++）与3（matlab）该两种语言的计算结果是一样的；

1（c语言）与2,3的计算结果是不一样的。

==============================以下为cvcvFilter2D( )与MATLAB中imfilter（）结果的对比==========================================

opencv中cvFilter2D( ) 函数与MATLAB中imfilter（）函数计算出的结果是不一样的。

首先对于MATLAB中的函数 imfilter( )

function b = imfilter(varargin)
%IMFILTER N-D filtering of multidimensional images.
%   B = IMFILTER(A,H) filters the multidimensional array A with the
%   multidimensional filter H.  A can be logical or it can be a 
%   nonsparse numeric array of any class and dimension.  The result, 
%   B, has the same size and class as A.
%
%   Each element of the output, B, is computed using double-precision
%   floating point.  If A is an integer or logical array, then output 
%   elements that exceed the range of the given type are truncated, 
%   and fractional values are rounded.
%
%   B = IMFILTER(A,H,OPTION1,OPTION2,...) performs multidimensional
%   filtering according to the specified options.  Option arguments can
%   have the following values:
%
%   - Boundary options
%
%       X            Input array values outside the bounds of the array
%                    are implicitly assumed to have the value X.  When no
%                    boundary option is specified, IMFILTER uses X = 0.
%
%       'symmetric'  Input array values outside the bounds of the array
%                    are computed by mirror-reflecting the array across
%                    the array border.
%
%       'replicate'  Input array values outside the bounds of the array
%                    are assumed to equal the nearest array border
%                    value.
%
%       'circular'   Input array values outside the bounds of the array
%                    are computed by implicitly assuming the input array
%                    is periodic.
%
%   - Output size options
%     (Output size options for IMFILTER are analogous to the SHAPE option
%     in the functions CONV2 and FILTER2.)
%
%       'same'       The output array is the same size as the input
%                    array.  This is the default behavior when no output
%                    size options are specified.
%
%       'full'       The output array is the full filtered result, and so
%                    is larger than the input array.
%
%   - Correlation and convolution
%
%       'corr'       IMFILTER performs multidimensional filtering using
%                    correlation, which is the same way that FILTER2
%                    performs filtering.  <span style="color:#FF0000;">When no correlation or
%                    convolution option is specified, IMFILTER uses
%                    correlation.</span>
%
%       'conv'       IMFILTER performs multidimensional filtering using
%                    convolution.

关于该函数，要说明的有两点：
1：该函数未指明是相关运算（correlation）还是卷积运算（convolution）时，默认使用相关运算。

2：该函数的运算结果（一般人都想要的结果）为下图所示：

而opencv中的卷积函数cvFilter2D( )

当kernel的大小为3*3时，计算出的结果为MATLAB计算出结果的5/6              也就是 7.5/9 =5/6

当kernel大小为5时，计算出的结果为MATLAB计算出结果的9/10  也就是22.5/25=9/10

我有去跟踪opencv的源码，但是看了一段时间也没搞清楚为啥，节约时间也就放弃了。

如果你看完源搞清楚了原因，欢迎分享，在评论区写出原因，以便需要的人去查看，谢谢！