why am i getting NaN from my function
显示 更早的评论
i was asked to write a function that gets b&w image and returns its entropy. im not allowed to use im_hist or entrtopy (obviously).
this is the function i wrote:
function [Entropy] = EntropyCalc(image)
image_hist = histogram(image);
values = image_hist.Values;
[size_x, size_y] = size(image);
total = size_x * size_y;
p = values./total;
Entropy = - sum(p.*log2(p));
end
but i keep getting NaN.
any ideas??
thanks!
采纳的回答
Thiago Henrique Gomes Lobato
2020-1-26
As David said your log2(p) is not safe, you can solve this problem by using this line of code:
Entropy = - sum(p.*log2(p+eps));
3 个评论
tomer orenshtein
2020-1-26
Thiago Henrique Gomes Lobato
2020-1-26
编辑：Thiago Henrique Gomes Lobato
2020-1-26
The difference is in the histogram function, you need to explicitely define the number of bins to 256 (make sure image is uint8) so it has the same result.
image_hist = histogram(image,256);
Or faster:
values = imhist(image(:));
tomer orenshtein
2020-1-26
更多回答（0 个）
类别
在 帮助中心 和 File Exchange 中查找有关 Interpolation of 2-D Selections in 3-D Grids 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
Translated by 
