Generate an indexed image

How do I create an indexed image to import into Matlab?. Thanks

Answer 1

[Image Analyst]

Try this:

% Demo by Image Analyst
clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
clear;  % Erase all existing variables. Or clearvars if you want.
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 20;
markerSize = 40;

% Read in original RGB image and display it.
originalImage = imread('peppers.png');
subplot(2, 1, 1);
imshow(originalImage);
impixelinfo;
title('Original Image', 'FontSize', fontSize)

% Create indexed image with 6 colors.
numColors = 6;
[indexedImage, cmap] = rgb2ind(originalImage, numColors);
% Save it to disk.
imwrite(indexedImage, cmap, 'indexedImage.png');

% Read indexed image back in from disk.
[recalledImage, storedColorMap] = imread('indexedImage.png');
% Display it.
subplot(2, 1, 2);
imshow(recalledImage, 'Colormap', storedColorMap);
caption = sprintf('Indexed Image with %d Colors', numColors);
title(caption, 'FontSize', fontSize)
% Display color bar and adjust range from 0-255 to 0-numColors.
colorbar;
caxis([0, numColors])
impixelinfo;
% Maximize figure window.
g = gcf;
g.WindowState = 'maximized';

Answer 2

[Benjamin Kraus]

Are you trying to create an indexed image in MATLAB? Or are you asking what programs (aside from MATLAB) can be used to create indexed image?

Some resources that may help:

• What is an indexed image?
• Image Types
• Image file formats supporting indexed color

If those links don't help, I think you are going to need to add a lot more detail to your question to get a helpful answer.

[Claudia Lucia Silva Olvera]

Hello Benjamin

What programs can I use to transform a normal image (.jpg, .png) into an indexed image, to later load it in Matlab?.

Thanks

[Benjamin Kraus]

Aside from using MATLAB itself to read in an image and transform it into an indexed image (MATLAB can read and write indexed and non-indexed images), I'm not familiar with what other image editing programs can be used to do that.

Why do you need to transform an image into an indexed image before reading it into MATLAB? Why not just read it directly into MATLAB?

[Claudia Lucia Silva Olvera]

Hi Benjamin

The truth did not know that the transformation could be done in MATLAB.

Thanks

Nice day