MATLAB: HISTEQ default not consistent with syntax

histeq

If I have an 8-bit image IM (e.g. cameraman.tif), why does histeq(IM) produce a different result than histeq(IM,ones(1,256))??

Shouldn't they be identical? The description says hgram defaults to ones(1,n)*prod(size(A))/n. Since cameraman is 256×256 and n=2^8, shouldn't it scale normally?

Best Answer

IM = imread('cameraman.tif');
I = histeq(IM);
I2 = histeq(IM,ones(1,64)*(numel(IM)/64));
isequal(I,I2)
ans =
       1

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MATLAB: Bounjours a tous , alors j’ai commence de trvaille avec matlab j’ai esseye de faire le produit de convolusion entre une image et un filtre gaussian avec la fonction conv2 mais je suis bloqué a cause de ca voila l’erreur:N-D arrays are not supported

Next time, use the {}Code button to format your code.

You did img=imread('image.jpg');, which results in a 3D matrix (column,row,color). You need to reduce that to two dimension, e.g. with img=imread('image.jpg');img=mean(img,3);.

MATLAB: Changing the output of the imread() function

Hey Seth,

Could you just use rgb2gray on the output of imread?

I = imread('mytiff.tif');
if size(I,3) == 3
    I = rgb2gray(I);
end

Or if you'd like to retain the colors, but still keep the image as 640x480 for some reason, you could use rgb2ind to create an indexed image. You'll need to store the map output as well though to maintain color information.

-Cam

Best Answer

Related Solutions

MATLAB: Bounjours a tous , alors j’ai commence de trvaille avec matlab j’ai esseye de faire le produit de convolusion entre une image et un filtre gaussian avec la fonction conv2 mais je suis bloqué a cause de ca voila l’erreur:N-D arrays are not supported

MATLAB: Changing the output of the imread() function

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