Question

I need some help with RGB capture in a image.
I am using impixel to manualy get RGB from a picture, but i would like to create a grid of let’s say 20×20 px boxes where it will automatically tell me for each box a RGB value. So in a picture lets say i have 20 boxes it will tell me 20 RGB values. Yeah an if there is 20% or more of white space that it ignores that rgb box.

Can you point me to some links or give me a general idea how to do this.

Best regards

P.S. image is just a .jpg, the background is white an in the middle there is an item.

UPDATE

This is my code for collecting RGB using impixel

px=impixel(img);        
st = num2cell(px,1);
zstup = cellfun(@sum,st); 
zred = size(px,1);         
rez = bsxfun(@rdivide,zstup,zred); 
trez=round(rez); 

What I want to do is :

http://imageshack.us/photo/my-images/696/exsample.jpg/

So every box like A1, A2, and so on will return RGB value like trez in my code.

So in my code i save my trez data in a table and it is like in excell lets say 220 | 23 | 34, now if i do that to another fruit i will have

220 | 23 | 34

123 | 212| 78

and so on…

Returning to automatization, A7 and A 15 would not be good RGB canditades because they have more then 50% white area so everything that has 20% white will be ignored.
So A31 is good and the RGB value needs to be saved.

So all in all here i would have my be 6 RGB values that would have to be automatically saved like the above example.
I know how to save to table i just need help for the gathering rgb values in every box.

Answer 1

Depending on your exact needs I see two solutions:

Downscale the image using impyramid(img, 'reduce'). This gives you a smaller image consisting of average values of the original image. Then do what you did before to access single pixels. Repeat as often as necessary to get 2×2, 4×4, 8×8 or larger “boxes”.

Or you could use define a box (or arbitrary shape) as a matrix of ones and zeros and use the regionprops function in order to get information about the images content depending on the fields containing ones:

roi = zeros(size(img))
roi(1:10,1:10) = 1;
r = regionprops(roi, img, 'MeanIntensity')
average = r.MeanIntensity