image processing - How to count number of small dots in a picture

I have this picture of small particles in a polymer film. I want to count how many particles in the figure, so that I can have a rough estimation of the particle density. But the image quality is poor, I had a hard time to do it.

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I have tried several ways to do it, but failed. below is the code. The first method I tried is:

`SetDirectory["C:\\Users\\mayao\\documents"]
image = Import["Picture3.jpg"];
imag2 = Binarize[image, {0.0, 0.8}];
cells = SelectComponents[DeleteBorderComponents[imag2], "Count", -400];


circles = ComponentMeasurements[ImageMultiply[image,cells],"Centroid", "EquivalentDiskRadius"}][[All, 2]]; Show[image, Graphics[{Red, Thick, Circle @@ # & /@ circles}]]

Here is what I got:

So it does not count all the particle. Plus, it sometimes take several particle as one.

I read another method from a thread here, the code is:

obl[transit_Image] := (SelectComponents[
     MorphologicalComponents[
      DeleteSmallComponents@
       ChanVeseBinarize[#, "TargetColor" -> Black], 
      Method -> "ConvexHull"], {"Count", "SemiAxes"}, 

     Abs[Times @@ #2 Pi - #1] < #1/100 &]) &@
  transit; GraphicsGrid[{#, obl@# // Colorize, 
    ImageMultiply[#, 
     Image@Unitize@
       obl@#]} & /@ (Import /@ ("C:\\Users\\mayao\\documents\\" <> # \
& /@ {"Picture1.jpg", "Picture2.jpg", "Picture3.jpg", 
       "Picture1.jpg"}))]

But it does not recognize the single particles:

Is there any other method to do this task? Thanks a lot for any suggestions.

Answer

get the binarize image

 img = Import["http://i.stack.imgur.com/0OJd7.jpg"];
 binimg = LocalAdaptiveBinarize[img, 25];

The effect like this:

    big = ImageDemosaic[binimg // ColorConvert[#, "Grayscale"] &, 
         "RGGB"] // MinDetect // SelectComponents[#, "Count", # > 100 &] &;

    (array = WatershedComponents[GradientFilter[big, 2], 
        DistanceTransform[big] // MaxDetect]) // Colorize

Then your number is

array // Max

1650

Update===========================================================

Use the Closing to optimize the binarize image.

binimg = Closing[LocalAdaptiveBinarize[img, 25], 3]

Then we get the array and verify the effect.

(array = WatershedComponents[GradientFilter[binimg, 2], 
    DistanceTransform[binimg // ColorNegate] // 
     MaxDetect]) // Colorize

Or you can like this:

Show[img, 
 Graphics[{Red, 
   Point[(array /. 1164 -> 0 // 
       ComponentMeasurements[#, "Centroid"] &)[[All, 2]]]}]]

So the number of your component is:

array // Max

1340