How to enhance contrast on a grayscale image?

How to call eqhist to make the lowest value white and the highest value balck?

[Jan]

@Mr M.: Please spend more time when asking a question to explain any details. Although the readers could guess, what your inputs are and what you want to get as output, it is more efficient, if you explain this explicitly. It is not clear what "eqhist" is, maybe you mean "histeq"?

Answer 1

[Jan]

If you mean "histeq", which details is not clear after reading the documentation: https://www.mathworks.com/help/images/ref/histeq.html ?

[Mr M.]

yes, histeq "How to call" I mean, how to set the input arguments. Not clear for me from the documentation.

[Jan]

@Mr M.: What are your inputs? If the lowest value should be white and the highest black, you have to subtract the output of histeq from the highest possible value, but it depends on the type of your input, what this is. Example:

Img = rand(640, 480) * 0.5;  % dark grey image, double format
Img2 = 1 - histeq(Img);
% UNTESTED - I do not have the signal processing toolbox

[Mohamed Moawed]

you can use imadjust() command

Answer 2

[Image Analyst]

histeq() is junk. Histogram equalization produces harsh, unnatural looking images. Don't do it. Use imadjust() instead. It uses a linear contrast stretch giving a more realistic and natural appearance for the output image.

[Mohamed Moawed]

you can use imadjust() command