MATLAB: Hue saturation intensity

image processing

I1 = imread('127.jpg');

>> I1 = imresize(I1, [256 256]);

>> [h s i] = rgb2hsi(I1);

??? Undefined function or method 'rgb2hsi' for input arguments of type 'uint8'.

>> I2 = double(I1);

>> [h s i] = rgb2hsi(I2);

??? Undefined function or method 'rgb2hsi' for input arguments of type 'double'.

how to i calculate intensity value

Best Answer

rgb2hsv() not rgb2hsi()

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MATLAB: Increase hue of image

Take the hue image, and multiply it by something.

hsvImage = rgb2hav(rgbImage);
hsvImage(:,:,1) = hsvImage(:,:,1) * someFactor;
rgbImage = hsv2rgb(hsvImage);

I think you really mean increase the saturation, but whatever... The saturation channel is 2, so switch to that if you really want that.

MATLAB: Color wave length and hue

Hue = (650 - wavelength)*240/(650-475);

Extracted from: http://www.physics.uoguelph.ca/applets/Intro_physics/refraction/LightRefract.java

Note: the denominator consists of two seemingly arbitrary limits in the code. The 240 refers to the maximum hue value of 240 that is used in standard 8 bit Hue representation.

Visible light is about 400 to 700 nm, with 650 nm being the frequency of red. 475 is blue. Both indigo and violet fall below this limit, but the CIE model that defines the theoretical map of wavelength to hue has to treat colors in that range separately, and it could be that 475 nm is the effective limit for standard Hue calculation, perhaps requiring negative Hue (yes, that is possible in color theory, but not in standard 8 bit Hue representation.)

Best Answer

Related Solutions

MATLAB: Increase hue of image

MATLAB: Color wave length and hue

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