MATLAB: How to change the more than one pixel values in gray scale image

change pixelgray scale

% I have gray image X (480×640 double), having values between 0 and 0 to 1, I want to change the values of all pixel to 1 that are closer to 1 and change values of all pixel to 0 that are near to 0.

Best Answer

Copying my answer from your duplicate question at http://www.mathworks.com/matlabcentral/answers/51939-how-i-can-change-the-certain-pixel-values-in-gray-scale-image:

Well, you shouldn't have accepted that answer so quickly if it didn't do what you asked. Here's how to "change the values of certain pixel to 1 that are closer to 1 and want to change values to 0 that are near to 0:

yourImage = yourImage >= 0.5;

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MATLAB: Change Pixel intensity value

Say your image is x,

x(x<0) = 0;

MATLAB: Imagesc & plot matrix

Salvatore, try this:

Im = [1.0000    0.7944    0.7361    0.8205    0.4192
0.7944    1.0000    0.8663    0.6780    0.3435
0.7361    0.8663    1.0000    0.7351    0.3311
0.8205    0.6780    0.7351    1.0000    0.3555
0.4192    0.3435    0.3311    0.3555    1.0000]
imagesc(Im)
cHandle = colorbar;
caxis([-1 1])           % This sets the visible range of colours
set(gca,'XTick',1:5,'YTick',1:5) % This sets the tick locations

You can also use different colours as seen in:

doc colormap

You can even supply your own colormap by building a matrix of N-by-3 values between 0 and 1.

The reason why your X/Y axes go from 0.5 to 5.5 is because every pixel has a size of 1 pixel. So the first pixel has a central location at [1,1]... but in order to show the whole pixel (with a width of 1 pixel), it has to start at location [0.5,05] and stretch to location [1.5,1.5]

A good explanation of this (with pictures) is at:

Doc > Image Processing Toolbox > Introduction

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Related Solutions

MATLAB: Change Pixel intensity value

MATLAB: Imagesc & plot matrix

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