Finding the contrast ratio of a grayscale image

50 次查看（过去 30 天）
iseinas
iseinas 2020-9-4
评论： Image Analyst 2021-7-11
So as the title says, I want to find the contrast ratio of a grayscale image by Michelson contrast definition. I'm thankful for any help! I'm not sure how to do this. Am I supposed to find the max and min value in each columns or row or the whole matrix?
% Michelson contrast definition
% Imax : the largest value in the image's matrix
% Imin : the smallest value in the image's matrix
contrast = (Imax-Imin)(Imax+Imin)

请先登录，再回答此问题。

采纳的回答

Image Analyst
Image Analyst 2020-9-6
Do you need loops, like this is a homework question that requires them? If not, just simply do
Imax = max(I(:))
Imin = min(I(:))
contrast = (Imax - Imin) / (Imax + Imin)
Notice that I'm using the correct formula. You are not. They subtract in the numerator, not divide like you have it.
  4 个评论
显示 2更早的评论
Itzhak Mamistvalov
Itzhak Mamistvalov 2021-7-11
Hey, I would like to ask an adition question about contrast ratio.
Im trying to calculate to Contrast Improvment Ratio (CIR) between enhanced and unenhanced images within region of interest R. This is the formula Im using:
where C(x, y) and C¯(x,y)C¯(x,y) are the local contrast values at (x, y) of the unenhanced and enhanced images, respectively.
The Local contrast value C(x, y) computed as
where p and a are the mean values within the center region (3 × 3) pixels and the neighborhood, or surrounding region, (7 × 7) pixels, respectively.
I have a problem to actually write this into a matlab code.
I would appreciate it if you could help, thanks!

请先登录，再进行评论。

更多回答（1 个）

royed
royed 2020-9-6
if the question is about just comapring the max and min in the images. You can find it quite simply by using (max(max(image)) and the same for the minimum which would return the pixel with the max and minimum intensity value.

类别

在 Help Center 和 File Exchange 中查找有关 Image Processing Toolbox 的更多信息

标签

产品

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by