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Re: Converting a magnified image of a line to a single

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  • Subject: [mg130577] Re: Converting a magnified image of a line to a single
  • From: Matthias Odisio <matthias at wolfram.com>
  • Date: Tue, 23 Apr 2013 00:04:04 -0400 (EDT)
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Dave,

On 4/20/13 4:41 AM, Dave Waddell wrote:
> I tried converting the result image to a graph so that I could apply a
> moving average and then fit a B-spline through it. As you can tell I'm new
> to Mathematica:
> data = ArrayRules@SparseArray@ImageData[result]
> It was all downhill after that. Another nudge would be appreciated.
> Thanks, Dave.
> 
> Dave,
> 
> On 4/17/13 1:30 AM, Dave Waddell wrote:
>> I have a magnified image of a 0.1mm line here:
>> http://www.d-a-v-e.org/images/Trace.jpg
>> ... this converts with Binarize very well:
>> http://www.d-a-v-e.org/images/Trace%20binary.jpg
>> ... but what I would like to do is convert it to a single pixel wide
> smoothed line running right up the middle. Any suggestions or pointers on
> how to do this in Mathematica would be appreciated.
>> Dave
>>
> 
> The sequence below seems like a good start.
> The documentation for the functions should help you understand what is going
> on in more details:
> 
> trace = Import["http://www.d-a-v-e.org/images/Trace.jpg";]
> 
> b = ColorNegate@Binarize[trace];
> b2 = SelectComponents[b, "Area", -1];
> b3 = FillingTransform@b2;
> dt = ImageAdjust@DistanceTransform@b3;
> result = ColorNegate@Image[WatershedComponents[dt], "Bit"];
> HighlightImage[trace, result]
> 
> 
> Matthias Odisio
> Wolfram Research

ImageValuePositions will give you the coordinates of the white pixels:

In[21]:= ImageValuePositions[Image[IdentityMatrix[3], "Bit"], 1]

Out[21]= {{0.5, 2.5}, {1.5, 1.5}, {2.5, 0.5}}

Please note that ImageValuePositions does not sort the returned
positions in any specific order.


Matthias



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