hue saturation intensity

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

Answer 1

[Walter Roberson]

rgb2hsv() not rgb2hsi()

[bala k]

i need to calculate intensity value

[Walter Roberson]

http://www.mathworks.com/matlabcentral/fileexchange/13630

[Teodora]

HSV color space is not the same as HSI color space, although similar they are.

[DGM]

The colorspace conversion utilities that are packaged with MIMT contain tools for conversion to and from HSI, HSL, and others.

https://www.mathworks.com/matlabcentral/fileexchange/53354-colorspace-conversion-tools

They are not identical in behavior to the builtin rgb2hsv(). The angles are in degrees instead of being normalized, and they do not support multiple output arguments. For that, just use imsplit().

There are other tools on the FEX for HSI, but many are only one-way. Be aware that Pascal Getreuer's popular Colorspace Transformations tool has an old bug which means that it actually does not support HSI conversions unless you build from MEX. If you're running the m-code only, the tool will convert to HSL when HSI is requested.