3D Histogram of a true color (RGB) image

I have to plot 3D histogram of a true color image, as shown in the attached screenshot.

Answer 1

[Vedant Shah]

Hi @Abdul Gaffar,

To plot a 3D histogram of a true colour image, try the following steps:

1. Convert it to a grayscale image, focusing on intensity values.

2. Then proceed by using the "meshgrid" function to determine the X and Y coordinates.

3. Finally, plot the 3D surface using the "surf" function.

For more information about the “meshgrid” and “surf” functions, you can refer to their official MATLAB documentation using the following commands:

web(fullfile(docroot, "/matlab/ref/meshgrid.html"))
web(fullfile(docroot, "/matlab/ref/surf.html")) 

Below is a reference MATLAB code snippet:

img = imread('image.jpg'); 

grayImg = rgb2gray(img);  
grayImg = double(grayImg); 

[X, Y] = meshgrid(1:size(grayImg, 2), 1:size(grayImg, 1)); 

figure; 
surf(X, Y, grayImg, 'EdgeColor', 'none');  
colormap jet;  
colorbar;  

This script generates a 3D surface plot where the height represents pixel intensity. Darker regions correspond to low intensity, while brighter regions indicate higher intensity values.

[DGM]

That's not a histogram. That's just an intensity map.