the raspi connect the monitor the show image delay

if true
 function [light_r,light_g,light_y]= fcn(img_R,img_G,img_B)
light_r =0;
light_g =0;
light_y =0;
img = uint8(zeros(320,240,3));
img(:,:,1) = img_R;
img(:,:,2) = img_G;
img(:,:,3) = img_B;
img_hsv = rgb2hsv(img);
%%%%%%%%%%%%%紅色區域的門檻值%%%%%%%%%%%%%%%%%%
h_redMin = 0.002;
h_redMax = 0.103;
s_redMin = 0.131;
s_redMax = 0.880;
v_redMin = 0.741;
v_redMax = 1.000;
%%%%%%%%%%%%%綠色區域的門檻值%%%%%%%%%%%%%%%%%%
h_greenMin = 0.248;
h__greenMax = 0.386;
s__greenMin = 0.298;
s__greenMax = 1.000;
v__greenMin = 0.129;
v__greenMax = 1.000;
%%%%%%%%%%%%%黃色區域的門檻值%%%%%%%%%%%%%%%%%%
h_yellowMin =  0.153;
h__yellowMax = 0.178;
s__yellowMin = 0.157;
s__yellowMax = 0.804;
v__yellowMin = 0.800;
v__yellowMax = 1.000;
%%%%%%%%%%%%%%%取出HSV值%%%%%%%%%%%%%%%%%%%%%%%%%
h = img_hsv(:,:,1);
s = img_hsv(:,:,2);
v = img_hsv(:,:,3);
bw =  ((h>=h_redMin) & (h <= h_redMax) & (s >= s_redMin) & (s<= s_redMax) & ...
    (v >= v_redMin ) & (v <= v_redMax))|((h >= h_greenMin ) & (h <= h__greenMax) & ...
  (s >= s__greenMin ) & (s <= s__greenMax) & (v >= v__greenMin ) & (v <= v__greenMax))| ...
  ((h >= h_yellowMin ) & (h <= h__yellowMax) & (s >= s__yellowMin ) & (s <= s__yellowMax) &(v >= v__yellowMin ) & (v <= v__yellowMax));
a = double(img); %原圖
b = bw; %二值圖 
c = uint8(cat(3,a(:,:,1 ).*b,a(:,:,2).*b,a(:,:,3).*b)); %結果
d = rgb2hsv(c);
h_d = d(:,:,1); 
s_d = d(:,:,2); 
v_d = d(:,:,3); 
[y,x,z] = size(c);
Red_y=zeros(y,1);
Green_y=zeros(y,1);
Yellow_y=zeros(y,1);
for i=1:y
  for j=1:x
      if((h_d(i,j)>=h_redMin) & (h_d(i,j) <= h_redMax)) & (s_d(i,j) >= s_redMin) & (s_d(i,j)<= s_redMax) & ...
              (v_d(i,j) >= v_redMin ) & (v_d(i,j) <= v_redMax)
          Red_y(i,1)= Red_y(i,1)+1;
      elseif((h_d(i,j) >= h_greenMin ) & (h_d(i,j) <= h__greenMax) & ...
              (s_d(i,j) >= s__greenMin ) & (s_d(i,j) <= s__greenMax) & (v_d(i,j) >= v__greenMin ) & (v_d(i,j) <= v__greenMax))
          Green_y(i,1)= Green_y(i,1)+1;
      elseif((h_d(i,j) >= h_yellowMin ) & (h_d(i,j) <= h__yellowMax) & (s_d(i,j) >= s__yellowMin ) & (s_d(i,j) <= s__yellowMax) & ...
          (v_d(i,j) >= v__yellowMin ) & (v_d(i,j) <= v__yellowMax))  
         Yellow_y(i,1)= Yellow_y(i,1)+1;
      end
  end
end
Max_Red_y=max(Red_y);
Max_Green_y=max(Green_y);
Max_Yellow_y=max(Yellow_y);
if((Max_Red_y> Max_Green_y)&&(Max_Red_y> Max_Yellow_y))
 light_r =1;
elseif((Max_Green_y> Max_Red_y)&&(Max_Green_y> Max_Yellow_y))
  light_g =1;
elseif((Max_Yellow_y> Max_Green_y)&&(Max_Yellow_y> Max_Red_y))
  light_y = 1;
else
  light_r =0;
  light_g =0;
  light_y =0;
end
end

i use this function on the simulink but embbeded the raspi the image have serious delay How can I improve?