Detect black dots from color background

Question

My short question

How to detect the black dots in the following images? (I paste only one test image to make the question look compact. More images can be found →here←

Answer 1

I was curios to test with my old 2d peak finder code on the images without any threshold or any color considerations, really crude don't you think?

im0=imread('Snap10.jpg');
im=(abs(255-im0));
d=rgb2gray(im);
filter=fspecial('gaussian',16,3.5);
p=FastPeakFind(d,0,filter);
imagesc(im0); hold on
plot(p(1:2:end),p(2:2:end),'r.')

The code I'm using is a simple 2D local maxima finder, there are some false positives, but all in all this captures most of the points with no duplication. The filter I was using was a 2d gaussian of width and std similar to a typical blob (the best would have been to get a matched filter for your problem). A more sophisticated version that does treat the colors (rgb2hsv?) could improve this further...