Cara Mengolah Citra Digital HSI ke RGB

Jika di postingan sebelumnya kita belajar cara merubah gambar RGB ke HSI, maka pada postingan kali ini kita akan membahas bagaimana cara merubah citra digital tipe HSI ke tipe RGB. Apilkasi atau software yang digunakan adalah Mathlab. Berikut adalah cooding yang digunakan

function rgb = hsi2rgb(hsi)
%HSI2RGB Converts an HSI image to RGB.
%   RGB = HSI2RGB(HSI) converts an HSI image to RGB, where HSI is
%   assumed to be of class double with:  
%     hsi(:, :, 1) = hue image, assumed to be in the range
%                    [0, 1] by having been divided by 2*pi.
%     hsi(:, :, 2) = saturation image, in the range [0, 1].
%     hsi(:, :, 3) = intensity image, in the range [0, 1].
%
%   The components of the output image are:
%     rgb(:, :, 1) = red.
%     rgb(:, :, 2) = green.
%     rgb(:, :, 3) = blue.

%   Copyright 2002-2004 R. C. Gonzalez, R. E. Woods, & S. L. Eddins
%   Digital Image Processing Using MATLAB, Prentice-Hall, 2004
%   $Revision: 1.5 $  $Date: 2003/10/13 01:01:06 $

% Extract the individual HSI component images.
H = hsi(:, :, 1) * 2 * pi;
S = hsi(:, :, 2);
I = hsi(:, :, 3);

% Implement the conversion equations.
R = zeros(size(hsi, 1), size(hsi, 2));
G = zeros(size(hsi, 1), size(hsi, 2));
B = zeros(size(hsi, 1), size(hsi, 2));

% RG sector (0 <= H < 2*pi/3).
idx = find( (0 <= H) & (H < 2*pi/3));
B(idx) = I(idx) .* (1 - S(idx));
R(idx) = I(idx) .* (1 + S(idx) .* cos(H(idx)) ./ ...
                                          cos(pi/3 - H(idx)));
G(idx) = 3*I(idx) - (R(idx) + B(idx));

% BG sector (2*pi/3 <= H < 4*pi/3).
idx = find( (2*pi/3 <= H) & (H < 4*pi/3) );
R(idx) = I(idx) .* (1 - S(idx));
G(idx) = I(idx) .* (1 + S(idx) .* cos(H(idx) - 2*pi/3) ./ ...
                    cos(pi - H(idx)));
B(idx) = 3*I(idx) - (R(idx) + G(idx));

% BR sector.
idx = find( (4*pi/3 <= H) & (H <= 2*pi));
G(idx) = I(idx) .* (1 - S(idx));
B(idx) = I(idx) .* (1 + S(idx) .* cos(H(idx) - 4*pi/3) ./ ...
                                           cos(5*pi/3 - H(idx)));
R(idx) = 3*I(idx) - (G(idx) + B(idx));

% Combine all three results into an RGB image.  Clip to [0, 1] to
% compensate for floating-point arithmetic rounding effects.
rgb = cat(3, R, G, B);
rgb = max(min(rgb, 1), 0); 

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