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I want to divide the 360 degree hue circle into 10 equal sector

Asked by susithra dhanavel on 16 Nov 2012

Hiii...

I want to divide a hue image into 10 sectors.for that first i multiplied obtained hue image by 360.how can i do this?? is there any function to divide hue image into sectors.

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susithra dhanavel

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2 Answers

Answer by Image Analyst on 17 Nov 2012
Edited by Image Analyst on 17 Nov 2012

How about logical indexing? Multiplying by 360 is not necessary. Why do you think it is?

h1 = h(h < 0.1);
h2 = h(h > 0.1 & h < 0.2);
h3 = h(h > 0.2 & h < 0.3);

etc. up to h10. If you want an image instead of a list of values, then you'll have to do masking

h2 = h .* double(h > 0.1 & h < 0.2);

etc.

9 Comments

susithra dhanavel on 13 Feb 2013

yes i want h1 through h10 to be 2D image..then what is the code in matlab??

Thorsten on 13 Feb 2013

See my code below. The B computed in each run of the loop are the h1, h2, ... images you need.

Image Analyst on 13 Feb 2013

See my demo:

clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
imtool close all;  % Close all imtool figures if you have the Image Processing Toolbox.
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;
% Read in a standard MATLAB color demo image.
folder = fullfile(matlabroot, '\toolbox\images\imdemos');
baseFileName = 'peppers.png';
% Get the full filename, with path prepended.
fullFileName = fullfile(folder, baseFileName);
if ~exist(fullFileName, 'file')
	% Didn't find it there.  Check the search path for it.
	fullFileName = baseFileName; % No path this time.
	if ~exist(fullFileName, 'file')
		% Still didn't find it.  Alert user.
		errorMessage = sprintf('Error: %s does not exist.', fullFileName);
		uiwait(warndlg(errorMessage));
		return;
	end
end
rgbImage = imread(fullFileName);
% Get the dimensions of the image.  numberOfColorBands should be = 3.
[rows columns numberOfColorBands] = size(rgbImage);
% Display the original color image.
subplot(3, 4, 1);
imshow(rgbImage, []);
title('Original Color Image', 'FontSize', fontSize);
% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);
hsv = rgb2hsv(rgbImage);
hueImage = hsv(:,:,1);
numberOfHues = 10;
for hue = 1 : numberOfHues
	% Get a binary image of where this hue is.
	mask = hueImage > (hue-1)/numberOfHues & hueImage <= hue/numberOfHues;
	% Extract it from the image
	% Mask the image.
	maskedRgbImage = bsxfun(@times, rgbImage, cast(mask,class(rgbImage)));
	subplot(3, 4, hue+1);
	imshow(maskedRgbImage);
	caption = sprintf('Hue #%d Image', hue);
	title(caption, 'FontSize', fontSize);
end
Image Analyst
Answer by Thorsten on 12 Feb 2013
Edited by Thorsten on 12 Feb 2013
Ncolors = 10;
I = imread('peppers.png');
HSV = rgb2hsv(I);
H = HSV(:,: ,1);
Hnew = zeros(size(H));
delta = 1/Ncolors;
for range = delta:delta:1
  B = H >= range - delta & H < range;
  Hnew(B>0) = range - delta/2;
end
HSV(:,:,1) = Hnew;
subplot(1,2,1), imshow(I)
subplot(1,2,2), imshow(hsv2rgb(HSVnew))

2 Comments

susithra dhanavel on 4 Apr 2013

Thank you...I want to create a 306 degree hue circle in matlab and then I want to divide that hue circle into ten sectors..i tried to create but I dint get it...what is the code to create hue circle???

Walter Roberson on 4 Apr 2013

Image Analyst's demo of February 13th shows you one way to proceed.

Thorsten

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