#One Way: Segmentation and useing Mask
im_original=read the image considering RGB Image
im_binary=imbinarize(rgb2gray(im_original),th);
#Segmentation
%. th^ Decide threshold value for good segementation
% Get the largest 2 blobs as per this case
mask_im=bwareafilt(im_binary,2);
total_pix=sum(mask_im(:));
#Mask the RGB Original Image
mask=cat(3,mask_im,mask_im,mask_im);
image_RGB=im;
image_RGB(~mask)=0;
#Average Pix
ave_pix=sum(image_RGB(:))/sum(mask(:));
disp(ave_pix); %Display the average pix
Hope it helps!
