How to get image brightness ?

Question

Gargolla9 2021-10-13

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1562971-how-to-get-image-brightness

评论： Gargolla9 2021-10-14

Img_0685.bmp

Hi everyone! I am new to MATLAB Image Processing and I need your help. I need to build a code that calculates this instantaneous apparent brightness m_inst, related to the straight line in figure. The exposure time of the frame that I have attached here is one second. Can anyone help me?

I have worked on a code like this to obtain the brightness of the pixels belonging to that straight line but I don't know if it is useful for the calculation of apparent brightness:

A=rgb2gray(imread('Img_0685.bmp'));
B=bwareafilt(imbinarize(A-medfilt2(A,[5,5])) ,1)  ;
pixelValues=A(B)
figure
imshow(B)

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

yanqi liu 2021-10-14

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1562971-how-to-get-image-brightness#answer_808226

在 MATLAB Online 中打开

clc; clear all; close all;

A=rgb2gray(imread('https://ww2.mathworks.cn/matlabcentral/answers/uploaded_files/766496/Img_0685.bmp'));

B=bwareafilt(imbinarize(A-medfilt2(A,[5,5])) ,1) ;

res=mean2(double(A(B)))

res = 230.1644

figure

imshow(B)

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

Answer 2

yanqi liu 2021-10-14

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1562971-how-to-get-image-brightness#answer_808316

在 MATLAB Online 中打开

clc; clear all; close all;

A=rgb2gray(imread('https://ww2.mathworks.cn/matlabcentral/answers/uploaded_files/766496/Img_0685.bmp'));

B=bwareafilt(imbinarize(A-medfilt2(A,[5,5])) ,1) ;

C=A.*uint8(B);

ci = unique(C(:));

ci_sum = 0;

for i = 1 : length(ci)

if ci(i) > 0

ci_num = length(find(C(:)==ci(i)));

ci_sum = ci_sum + ci_num;

end

n = length(find(C(:)>0));

csky = length(find(C(:)==0));

t = 1;

minist = 30 - 2.5*log10((ci_sum-n*csky)/t)

minist = 10.7431 - 3.4109i

figure

imshow(C)

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Gargolla9 2021-10-14

Thank you for your idea but I think that something is wrong: for this frame that I have attached here and also for others frame that I have, the value of ci_sum and n is always the same; another problem is the fact that the final result, m_inst, is a complex value but it must be a real value.

请先登录，再进行评论。