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location Munich, Germany
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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.


2d
awarded  Nice Question
Jan
16
comment Plotting y'[x] vs y[x]
ParametricPlot?
Jan
14
comment How can I detect if an image is in or out of focus?
Related: stackoverflow.com/questions/7765810/…
Jan
12
comment How can FactorInteger be so slow if PrimeQ is fast?
@DanielLichtblau: reading an 8th grade math book might lead one to believe that factorizing an integer is the only way to find out if it's prime ;-)
Jan
9
comment Can I force Mathematica to use machine precision?
Thanks @OleksandrR., SystemSetSystemOptions["CatchMachineUnderflow" -> False];` works perfectly. I did look for similar questions, but didn't find the one you linked. It's obviously a duplicate. Should delete it myself or vote to close?
Jan
9
asked Can I force Mathematica to use machine precision?
Jan
9
comment Is there a way to characterize a winding object in an image?
+1. If you only want the local maxima of the distance transform, you can use SkeletonTransform. If Mean/Max are not enough, you can use ComponentMeasurements[... "Data" to get the pixel values in the distance transform/skeleton image.
Dec
24
revised Integers which are the sum of both two and three consecutive squares
added 37 characters in body
Dec
24
answered Integers which are the sum of both two and three consecutive squares
Dec
14
comment ReplaceImageValue and ReplacePixelValue extremely slow
If you just want to highlight pixels, you can use: HighlightImage[image, bin], which is very fast. In general, working with coordinates/indices seems to be much slower than using converting images to arrays with ImageData and using simple arithmetic.
Dec
8
awarded  Good Question
Dec
4
comment Mask outliers in an image
You wrote "I can do the outliner detection" but you didn't give any details: What's the result of your outlier detection? A list of coordinates? A binary image (or 2d array)? Component data from ComponentMeasurements? Also: working with lists of indices is often much slower than working with a 2d array containing 0's and 1's (because of vectorization).
Dec
2
awarded  Good Answer
Nov
18
comment What does it mean: “Assuming a matrix | Use a list of lists instead”?
In Mathematica, a matrix is just a list of lists, so don't worry. This just means that the suggestions bar offers suggestions for matrices. If you clicked on "list of lists", you'd see different suggestions.
Nov
13
comment More on performance of Sum[]
I would guess that the resolution of AbsoluteTiming is system dependent. For example, on my Win 7 PC, I never get a value between 0 and 0.0005, so that's probably the resolution of some clock that AbsoluteTiming uses. If you compare only timings large compared to the clock resolution (e.g. t > 0.01), the graphs do look very similar.
Nov
13
comment Finding a specific number of eigenvalues in Mathematica
If m is a square matrix, then Eigenvalues[m,n] gives the first n eigenvalues.
Nov
13
comment FindPeaks does not smooth noise on peak?
MaxDetect[data, 0.01] where 0.01 is a "noise threshold" is also worth a try - the resulting vector is 1 for (possibly extended) maxima, and 0 elsewhere.
Nov
6
comment Best fit equation from a scanned image
Related: mathematica.stackexchange.com/questions/3831/…
Nov
4
awarded  Good Question
Oct
29
comment Usage of @ symbol in Mathematica
Have you seen this? mathematica.stackexchange.com/questions/18393/…