i want to convert an image from rgb to xyz and want to get the values of x and y and z separately. so i am having a problem. how can i encounter the problem?????

RGB = [255; 255; 255 ];

rRGB=RGB(:,:,1);

gRGB=(RGB(:,:,2)./RGB(2)) * 100;

bRGB=RGB(:,:,3);

M = [0.4124564 0.3575761 0.1804375
  0.2126729 0.7151522 0.0721750
  0.0193339 0.1191920 0.9503041] ;
X = rRGB  * 0.4124564  + gRGB * 0.2126729  + bRGB*  0.0193339;
Y = rRGB  * 0.3575761  + gRGB * 0.7151522 + bRGB*   0.1191920;
Z=  rRGB  *  0.0193339  + gRGB * 0.1191920   + bRGB* 0.9503041 ;
so when i am running the programme i am getting this error

??? Index exceeds matrix dimensions.

Error in ==> pd at 3 gRGB=RGB(:,:,2)./RGB(2);

by d way when i am putting RGB=imread('F:\47.jpg', 'jpg') then i m getting a result..... what is the problem in the code???

[Thorsten]

A more elegant way to compute XYZ is

XYZ = M*squeeze(RGB)

(given that RGB is a 1x1x3 matrix.)

Answer 1

[Guillaume]

Your RGB is a 3x1x1 matrix. There's only one valid value for the index in the third dimension (1), so

RGB(:, :, 2)
RGB(:, :, 3)

are both invalid.

Probably, you meant to declare RGB as

RGB(1, 1, :) = [255 255 255];

[pritha Das]

thank you very much