double_rgb2ycrcb.m

基于FPGA的YUV转换RGB的色度空间转换

function [matlab_y, matlab_cr, matlab_cb] = double_rgb2ycrcb(R,G,B, AC, BC, CC, DC)
    % double precision YCrCb to RGB color-space conversion.
    % Coefficients derived from RGB to YCrCb conversion matrix
    % Inputs R, G and B are assumed in the 0.0 - 1.0 range

    % AC=612/2048;        % 0.299   => Biometric constants
    % BC=233/2048;        % 0.114    
    % CC=0.5/(1-AC);      % Scaling constants reducing the dynamic range 
    % DC=0.5/(1-BC);      % of Cb and Cr to -0.5 to 0.5 (0 to 1 with offset compensation
    COFFSET = 0.5;
    YOFFSET = 0;
    
    min_val = min(min(min([R,G,B])));
    max_val = max(max(max([R,G,B])));
    range = max(2,pow2(ceil(log2(double(max_val-min_val)))))-1;
    if (min_val<0) min_p2 = -pow2(ceil(log2(double(-min_val)))); 
    else min_p2 = 0;  end ;      
    
    r = double(R-min_p2)/range;    % normalizing inputs to the 0..1 range;
    g = double(G-min_p2)/range;
    b = double(B-min_p2)/range;
    matlab_y=AC*r+(1-AC-BC)*g+BC*b;
    matlab_cr=CC*(r-matlab_y)+COFFSET;
    matlab_cb=DC*(b-matlab_y)+COFFSET;
end