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location Munich, Germany
age 36
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I work at a small mechanical engineering company, where I develop software and image processing algorithms for camera-based inspection machines.


Mar
24
comment Extracting road curves from an image
@P.Fonseca: I tried, but exported as gif the animation was ~30 MB... (swf and qt were both between 1-2 MB)
Mar
24
awarded  Enlightened
Mar
24
awarded  Nice Answer
Mar
24
revised Extracting road curves from an image
added 3 characters in body
Mar
24
comment Extracting road curves from an image
@Pickett: Weird. The documentation doesn't say that this syntax is new, and I could have sworn I've used it like this since v8. OTOH, the speed difference isn't that large (in this case) so I'll change it to your version.
Mar
24
comment Extracting road curves from an image
@Pickett: Weird. I've just executed the code in a fresh MMA session, and except for the Show-problem Zviovich mentioned, it worked fine. Does whitePixels contain a list of 2d coordinates in your session? Or maybe -> Automatic syntax is newer than your MMA version?
Mar
24
comment Extracting road curves from an image
@Zviovich: I've used bgnd=Image[bgnd], to make my experiments with colorDist faster. I didn't realize this changed the behavior of Show. I've updated my answer. Regarding the title: Maybe something like "Extracting road graphs from an image"?
Mar
24
revised Extracting road curves from an image
added 12 characters in body
Mar
23
answered Extracting road curves from an image
Mar
22
answered How to add a static JPEG into a Manipulate without slowing it down
Mar
20
comment Efficient way to compute the gradient
I'm not sure what you're trying to do, but it sounds like Differences or ListConvolve would do what you want. Or possibly DerivativeFilter, maybe even GaussianFilter...
Mar
19
awarded  Nice Answer
Mar
13
answered Image processing for extracting regions of book pages that are covered by text
Mar
9
comment Can I solve this graph theory problem with Mathematica?
I see. The solution got lost in translation...
Mar
9
comment Can I solve this graph theory problem with Mathematica?
Which number is which? Could you maybe draw one of them in a graph? I thought they were top-to-bottom, left-to-right, but then 4,5 in the first example would be neighbors.
Mar
4
awarded  Popular Question
Feb
20
answered Calculating displacement for a circular disc
Feb
11
comment Using 2D Fourier transform of an image to detect typical wavelengths
@SjoerdC.deVries is right, I didn't notice that. IIRC, this is done to "rotate" the 0 frequencies to the center of the FFT output. If you want to interpret the values numerically (instead of displaying the FT as a picture), you'd want to remove that line.
Feb
11
comment Using 2D Fourier transform of an image to detect typical wavelengths
fw contains the values. I.e. fw[[1,1]] is the value for frequency 0/0, fw[[1,2]] is the value for frequency 0/1...
Feb
7
comment Efficient Lloyd Sampling of Images
Calculating the distance to the nearest seed for each pixel, good idea, I didn't think of that! It might get slower if nx and ny get large (10^4? 10^5?), but for 200, it's pretty fast. I don't have time to update my answer right now, but I think Nearest[seeds -> Range[Length[seeds]], pos][[All, All, 1]] is even faster than your Compiled code.