matlab 函数 strel("line") 到 python答案

【问题标题】：matlab function strel("line") to pythonmatlab 函数 strel("line") 到 python
【发布时间】：2019-01-03 01:33:39
【问题描述】：

我想在python中使用matlab函数strel("line")

我找到了类似 scikit-learn / opencv / mahotas

之类的 python 库

但我找不到它。

最后，我在 pymorph 'seline' 中找到了类似的函数，但它与 matlab 的 strel 函数不同。

具体来说，我想使用（或实现）strel("line") 并旋转它。

像 strel("line", length, degree)

Matlab 示例

a = strel("line",5,0)
b = strel("line",5,30)
c = strel("line",5,45)

输出是

像这样。

谁知道matlab的strel("line",length,degree)函数或者python库等于strel("line",length,degree)的算法，请告诉我。谢谢。

【问题讨论】：

标签： python matlab image-processing image-morphology

【解决方案1】：

对于此类问题，您可以随时查看 Octave 项目提供的代码。

使用this link可以看到函数strel是如何在Octave中实现的。

以下代码完全摘自Octave的strel函数，对应案例strel('line')：

## Parameters (degrees and linelenght)
degrees = 30
linelen = 5


## Line length are always odd, to center strel at the middle of the line.
## We look it as a diameter of a circle with given slope
deg90 = mod (degrees, 90);
if (deg90 > 45)
   alpha = pi * (90 - deg90) / 180;
else
   alpha = pi * deg90 / 180;
endif
   ray = (linelen - 1)/2;

## We are interested only in the discrete rectangle which contains the diameter
## However we focus our attention to the bottom left quarter of the circle,
## because of the central symmetry.
c = round (ray * cos (alpha)) + 1;
r = round (ray * sin (alpha)) + 1;

## Line rasterization
line = false (r, c);
m = tan (alpha);
x = [1:c];
y = r - fix (m .* (x - 0.5));
indexes = sub2ind ([r c], y, x);
line(indexes) = true;

## We view the result as 9 blocks.
# Preparing blocks
linestrip = line(1, 1:c - 1);
linerest = line(2:r, 1:c - 1);
z = false (r - 1, c);

# Assemblying blocks
SE.nhood =  vertcat (
    horzcat (z, linerest(end:-1:1,end:-1:1)),
    horzcat (linestrip, true, linestrip(end:-1:1,end:-1:1)),
    horzcat (linerest, z(end:-1:1,end:-1:1))
    );

# Rotate/transpose/flip?
sect = fix (mod (degrees, 180) / 45);
switch (sect)
    case 1, SE.nhood = transpose (SE.nhood);
    case 2, SE.nhood = rot90 (SE.nhood, 1);
    case 3, SE.nhood = fliplr (SE.nhood);
    otherwise, # do nothing
endswitch

SE

【讨论】：