Working with RGB images

I have a bunch of photos. Each photo I should divide into R,G and B channels (this part I completed successfully). Then I need to calculate average value of R, G and B for each photo (calculate average R for R photos, G for G photos, etc.) and build plots where X is number a photo, Y is average value of color). So there are 2 problems:

1. How do I create cycle in this case?
2. How do I count this average values and then build 3 plots? ( I guess I should write down all values into matrix and then build plots but I am quite unexperienced in Matlab, so there are problems with writing appropriate Matlab code).

Many thanks!

Answer 1

[KALYAN ACHARJYA]

1. "How do I create cycle in this case?"

Loop as discussed in below

1. 2. "How do I count this average values and then build 3 plots?"

Lets say, R_plane,G_plane and B_plane are the R,G,B plane of RGB image (You mentioned: this part I completed successfully), Average

r_average=mean(R_plane(:));
g_average=mean(G_plane(:));
b_average=mean(B_plane(:));

For do the same of multiple images, you are advised the call images one by one and save the average values in array. To call the multiple images one by one and do operation, please see my this answer.

for ..inside 
r_average(i)=mean(R_plane(:));
g_average(i)=mean(G_plane(:));
b_average(i)=mean(B_plane(:));
end 

Now

r_average, g_average, and b_average are three array, with size total number of images. Now you can do Bar plot (x images number and y as average number of corresponding image), outside the loop

r_average=[];
g_average=[];
b_average=[];
InputImages=....
for ..inside 
r_average(i)=mean(R_plane(:));
g_average(i)=mean(G_plane(:));
b_average(i)=mean(B_plane(:));
end 
subplot(131), bar(r_average);
subplot(132), bar(g_average);
subplot(133), bar(b_average);

or if you insisted to use plot

x_data=[1:length(InputImages)];
subplot(131), plot(x_data,r_average);
subplot(132), plot(x_data,g_average);
subplot(133), plot(x_data,b_average);

Or see stem

Hope I understand your question.

Good Luck!

[Fedor Durnev]

Oh, thanks a lot! I missed only one thing: what should I put in in InputImages? Path to folder with photos, right?

r_average=[];

g_average=[];

b_average=[];

InputImages=....

for ..inside

r_average(i)=mean(R_plane(:));

g_average(i)=mean(G_plane(:));

b_average(i)=mean(B_plane(:));

end

subplot(131), bar(r_average);

subplot(132), bar(g_average);

subplot(133), bar(b_average);

[KALYAN ACHARJYA]

yes, please refer my answer here

[Fedor Durnev]

Great! Thanks a lot!

[KALYAN ACHARJYA]

You're welcome!