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image processing - How to count proportion of two phase in a electron microscope picture


I have a picture:



enter image description here


The sunk area is a phase,and the bulged area in another phase.I want count the proportion of this two area.this is my method.First I get the mask by Image-Tool.


enter image description here


you can download to use it.


enter image description here


gra = GradientFilter[img, 2];
ImageCompose[img, {(comp = WatershedComponents[gra, mask]) // 
   Colorize[#, ColorRules -> {13 -> Transparent}] &, 0.6}]

enter image description here



Then the result is appear:


ComponentMeasurements[comp, "Count"] // SortBy[#, Last] & // 
    Values // {Total[Most[#]], Last[#]} & // #/Total[#] & // N


{0.547061, 0.452939}



But as you see,some unsatisfactory place like this place lead to the result is imprecise.:


enter image description here


BTW,the use of Image-Tool to pick so many component is very unadvisable.Can anybody give a more smart and more precise solution?



Update:


As the @SimonWoods 's request,I process the origional picture by PhotoShop and upload it:


enter image description here



Answer



Here's an idea that could work: The "Ferrite" areas have a border that's slightly darker than the background, while the area in between has a border that's slightly brighter than its neighborhood. So a filter that compares each pixel with the average brightness in the neighborhood, like an LoG filter should be a good start:


img = Import["http://i.stack.imgur.com/dMLH5.png"];    
(log = LaplacianGaussianFilter[img, 2]) // ImageAdjust

enter image description here


In this image, the border around the Fe-Areas is a bit lower than 0, the border around the "background" areas is a bit larger than 0, and the rest is around 0. So we can binarize this image to get the interior border:



filter = SelectComponents[#, "Length", # > 10 &] &;
bin = filter@MorphologicalBinarize[log, {0.05, 0.1}]

enter image description here


(Where I've used SelectComponents to remove some of the "noise" - you can play with additional criteria to get better results.)


And we can do the same thing with the sign flipped to get the "outer" border:


binO = filter@
  MorphologicalBinarize[ImageMultiply[log, -1], {0.05, 0.1}]

enter image description here



Now, pixels closer to the outer border are "background" pixels, and pixels closer to the inner border area "ferrite" pixels. So we simply calculate a Distance transform of the two border masks, and take the difference:


dt = DistanceTransform[ColorNegate[bin]];    
dtO = DistanceTransform[ColorNegate[binO]];    
(dtDiff = Image[ImageData[dtO] - ImageData[dt]]) // ImageAdjust

enter image description here


And mark pixels with distance difference < 0


HighlightImage[img, Binarize[dtDiff, 0]]

enter image description here



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