how can i perform gray scale image normalization???

91 次查看（过去 30 天）

显示更早的评论

mmm ssss 2012-1-18

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/26460-how-can-i-perform-gray-scale-image-normalization

评论： Syed Ahson Ali Shah 2022-2-10

在 MATLAB Online 中打开

i want to implement normalization to gray scale image to reduce the effect of illumination's differences.

the eq. of the grayscale normalization is :

y=((x-min)*255/(max-min))

x : gray scale value of original image.

y : gray scale value of op image(after normalization).

min : minimum gray scale for the original image.

max : maximum gray scale for the original image.

i tried to perform this by :

m=imread();
min1=min(min(m));
max1=max(max(m));
y=((m-min1).*255)./(max1-min1);
imshow(m);figure,imshow(y);

but it is wrong code .

i dont know why ?

is there any help?

regards

5 个评论
显示 3更早的评论隐藏 3更早的评论

Walter Roberson 2012-1-19

We would need to see the current code.

Xylo 2014-3-11

you can use double() before main function....

y=double((m-min1).*255./(max1-min1)); and as m is a 2D variable, y should be 2D variable. i.e u have to write as for i=1:m for j=1:n y(i,j)=double((m(i,j)-min1).*255./(max1-min1)); end end

请先登录，再进行评论。

请先登录，再回答此问题。

回答（3 个）

Image Analyst 2012-1-19

4
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/26460-how-can-i-perform-gray-scale-image-normalization#answer_34534

在 MATLAB Online 中打开

Or you can simply do this:

normalizedImage = uint8(255*mat2gray(grayImage));
imshow(normalizedImage);

and not worry about the normalization because mat2gray will do it for you.

4 个评论
显示 2更早的评论隐藏 2更早的评论

mmm ssss 2012-1-19

image analyst

i think that your opininon is correct but, in many paper they use the grayscale normalization to reduce the differences in illumination.

Image Analyst 2012-1-19

Then maybe their algorithm uses image normalization as just one step in the process and maybe you're not doing all the steps. Or else maybe their algorithm is not appropriate for the kind of video or images you have.

请先登录，再进行评论。

Syed Ahson Ali Shah 2022-2-8

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/26460-how-can-i-perform-gray-scale-image-normalization#answer_891470

编辑：Syed Ahson Ali Shah 2022-2-10

This is the Formula:

Normalized Image = (Original image - min of image) * ((newMax-newMin) / (ImageMax - ImageMin)) + newMin

where newMax and newMin is 255 and 0 respectively for the case when normalization is between 0 to 255.

2 个评论
显示无隐藏无

Image Analyst 2022-2-8

在 MATLAB Online 中打开

No it's not:

Originalimage = [100, 200]
Originalimage = 1×2
   100   200
minofimage = min(Originalimage(:));
ImageMin = min(Originalimage(:));
ImageMax = max(Originalimage(:));
newMax = 255;
newMin = 0;
% Do the formula he gave.
NormalizedImage = (Originalimage - minofimage) * ((newMax-newMin) / (ImageMax - ImageMin)) + newMax
NormalizedImage = 1×2
   255   510
% Do my formula:
normalizedImage = uint8(255*mat2gray(Originalimage))
normalizedImage = 1×2
     0   255

Syed Ahson Ali Shah 2022-2-10

There was typo mistake. I corrected now.

My answer is 100% correct. I guarantee

请先登录，再进行评论。

Walter Roberson 2012-1-18

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/26460-how-can-i-perform-gray-scale-image-normalization#answer_34524

在 MATLAB Online 中打开

I would suggest you use

y = uint8(255 .* ((double(m)-min1)) ./ (max1-min1));

With your existing code, the (x-min) would be okay, but multiplying by 255 would get saturation to 255 whenever the difference was not 0, and then you would get integer division of that 0 or 255 by the range interval.