Hi Aparna Sathya Murthy ,

Yes I am using MATLAB.

Aparna Sathya Murthy Can you help me with this ?

I just want to compare histogram (distance between two histogram). Something like in attached picture. In my case it will be comparing 3 lines (RGB image) instead of 1.

I think for RGB Histogram we need to compare only y axis as x axis (intensity) will be same for all the images (0 to 255).

thank you Aparna Sathya Murthy I will wait for your answer

Aparna Sathya Murthy

I tried it and I am getting an error

Undefined function or variable 'ca'.

Error in HistMatch (line 4)

TmpBlk=ca(i,j);

I think ca function is not defined.

Can you use attached images for comparison ?

split.m is splitting only one image. How will it compare to the other image ?

I tried as per attached script but still getting some error.

Index in position 1 exceeds array bounds (must not exceed 3).

Error in split_hist (line 89)

TmpBlk=ca(i,j);

Aparna Sathya Murthy

I figured out another way to split both images as below:

%%%%%%%%%%%%%%%%%%%%%

clear

clc

%inputs:

% img: an image (2D or 3D numeric array)

% M, N: the number of blocks along the rows, columns respectively

%output:

% block: a M x N cell array of 2D or 3D numeric arrays

img1 = imread('P_originalC.png');

M = 3;

N = 7;

blocks1 = mat2cell(img1, ones(1, M) * size(img1, 1) / M, ones(1, N) * size(img1, 2) / N, size(img1, 3)); %will error if M and N are not divisors of H and W

% second image

img2 = imread('P_TransformedC.png');

M1 = 3;

N1 = 7;

blocks2 = mat2cell(img2, ones(1, M1) * size(img2, 1) / M1, ones(1, N1) * size(img2, 2) / N1, size(img2, 3)); %will error if M and N are not divisors of H and W

%%%%%%%%%%%%%%%%%%%%%%%%

So now blocks1 will have 3 x 7 blocks of 'P_originalC.png'

blocks 2 will have 3 x 7 blocks of 'P_transformedC.png'

Now I don't know how to generate histogram of each block and compare them to get similarity value or distance.

Can you please help me with this ?

@Aparna

Will it work for some other matrix (not 5x5)?

Aparna Sathya Murthy

Because for some reason it is not working for me 1) I have Two images: 'P_o3x3.png' and 'P_t3x3.png' (Attached ) image size : 369 x 330 pixels (both images) That's why I will divide them into 3 x 3 blocks (total 9 blocks) 2) I want to generate the RGB histograms for each blocks so for 1 image there will be total 9 RGB histograms (If you separate each color channel then 27 histograms for 1 image) 3) I want to save these histograms into one matrix. (total 2 matrix for two different images) 4) Then I want to compare this 2 matrix with each-other for the similarity. I tries attached code: SplitHistMatch.m Images are attached can you please help me generate histogram matrix for both the images. Thank you very much for your help and support

Aparna Sathya Murthy

Thank you