C &引用；“不连续性”；图像边缘的高斯模糊

我一直在尝试实现nxn图像的高斯模糊函数，其高斯核的具体半径为rs=（（int）2.75*sigma+0.5）

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for（x=0；x让我们看一看应用于图像的典型过滤器内核，使用伪代码

# source[y][x]    Old image (read-only)
# target[y][x]    New image (write-only)
# image_height    Image height (y = 0 .. image_height-1)
# image_width     Image width (x = 0 .. image_width-1)
# filter[y][x]    Filter (weights) to be applied
# filter_height   Filter height (y = 0 .. filter_height-1)
# filter_width    Filter width (x = 0 .. filter_width-1)
# filter_y        Target pixel y coordinate in filter (filter_height/2)
# filter_x        Target pixel x coordinate in filter (filter_width/2)

其中
filter\u y=floor（filter\u width/2）
和
filter\u x=floor（filter\u height/2）
如果滤波器位于目标像素的中心（即对称），则伪码大致为

For base_y = 0 to image_height - 1:

   # y range relative to base_y ...
   min_y = -filter_y
   max_y = filter_height - 1 - filter_y

   # ... must not exceed the image boundaries.
   If min_y + base_y < 0:
       min_y = -base_y
   End If

   If max_y + base_y < 0:
       max_y = -base_y
   End If

   If min_y + base_y >= image_height:
       min_y = image_height - 1 - base_y
   End If

   If max_y + base_y >= image_height:
       max_y = image_height - 1 - base_y
   End If

   For base_x = 0 to image_width - 1:

       # x range relative to base_x ...
       min_x = -filter_x
       max_x = filter_width - 1 - filter_x

       # ... must not exceed the image boundaries.
       If min_x + base_x < 0:
           min_x = -base_x
       End If

       If max_x + base_x < 0:
           max_x = -base_x
       End If

       If min_x + base_x >= image_width:
           min_x = image_width - 1 - base_x
       End If

       If max_x + base_x >= image_height:
           max_x = image_width - 1 - base_x
       End If

       ValueSum = 0
       WeightSum = 0

       For y = min_y to max_y:
           For x = min_x to max_x:
               Value = source[y + base_y][x + base_x]
               Weight = filter[y + filter_y][x + filter_x]
               ValueSum = ValueSum + Value * Weight
               WeightSum = WeightSum + Weight
           End For
        End For

        If WeightSum != 0:
            target[base_y][base_x] = ValueSum / WeightSum
        End If

    End For
End For

在外环内部（无需为每个
base_x
！）打印它），以及

一旦进入最里面的循环（无需为每个
base\u y
再次打印），例如
if（y==0）printf（“…”）
。这将输出
image\u width+image\u height
行，并让您验证定义的范围是否正确

在OP的情况下，图像边缘附近的范围不正确；即，与上述伪代码对应的一些
if
子句计算/分配不正确的
min\u x
，
max\u x
，
min\u y
和
max\u y
值。我看不出您的计算有任何错误，但可能是舍入错误或者。你每一步都在转换为整数，如果你将所有数据存储为浮点或双精度进行计算，然后在最后将其四舍五入到最接近的整数，你会得到更好的结果。你每次转换为整数的方式都有很大的误差。我尝试将sum/wghtsum存储到单独的浮点矩阵中，然后将其再次写入int中的像素，但它的作用是相同的。我指的是您在几乎每个步骤中都执行的对
int
的转换。确保所有类型为double的变量，并删除
（int）的每个实例
，这会在小数点可能包含重要数据时截断小数点，特别是因为您执行了多次计算。您可能会被大量截断。简言之，这个答案的要点是偏移每个像素的内核加权和，因此有效内核和总是加在一起。他通过计算内核来实现这一点每次有效应用l单元格值，并将结果值除以它。整洁的解决方案，我喜欢！（如果我错了，请纠正我）
For base_y = 0 to image_height - 1:

   # y range relative to base_y ...
   min_y = -filter_y
   max_y = filter_height - 1 - filter_y

   # ... must not exceed the image boundaries.
   If min_y + base_y < 0:
       min_y = -base_y
   End If

   If max_y + base_y < 0:
       max_y = -base_y
   End If

   If min_y + base_y >= image_height:
       min_y = image_height - 1 - base_y
   End If

   If max_y + base_y >= image_height:
       max_y = image_height - 1 - base_y
   End If

   For base_x = 0 to image_width - 1:

       # x range relative to base_x ...
       min_x = -filter_x
       max_x = filter_width - 1 - filter_x

       # ... must not exceed the image boundaries.
       If min_x + base_x < 0:
           min_x = -base_x
       End If

       If max_x + base_x < 0:
           max_x = -base_x
       End If

       If min_x + base_x >= image_width:
           min_x = image_width - 1 - base_x
       End If

       If max_x + base_x >= image_height:
           max_x = image_width - 1 - base_x
       End If

       ValueSum = 0
       WeightSum = 0

       For y = min_y to max_y:
           For x = min_x to max_x:
               Value = source[y + base_y][x + base_x]
               Weight = filter[y + filter_y][x + filter_x]
               ValueSum = ValueSum + Value * Weight
               WeightSum = WeightSum + Weight
           End For
        End For

        If WeightSum != 0:
            target[base_y][base_x] = ValueSum / WeightSum
        End If

    End For
End For

printf("y = %d, ymin = %d (%d), ymax = %d (%d)\n",
       base_y, min_y, min_y + base_y, max_y, max_y + base_y);

printf("x = %d, xmin = %d (%d), xmax = %d (%d)\n",
       base_x, min_x, min_x + base_x, max_x, max_x + base_x);