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| bio | website | |
|---|---|---|
| location | Munich, Germany | |
| age | 35 | |
| visits | member for | 1 year, 3 months |
| seen | 25 mins ago | |
| stats | profile views | 440 |
I work at a small mechanical engineering company, where I develop software and image processing algorithms for camera-based inspection machines.
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2d |
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How can I detect an ellipse in a photo? I'm not sure about the hough transform: an ellipse has 5 degrees of freedom, that's a huge parameter space to update for each point. |
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May 12 |
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Does LinearModelFit perform an ordinary linear regression (least squares)? @Rojo: Thanks! That's exactly what I wanted to know. |
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May 9 |
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How can I return the color at a coordinate in an image? This gives the wrong values! The values in p are coordinates, so they are 0-based, start at the bottom-left corner and are stored in x/y order. Extract expects array indices, which are 1-based, start at the top-left corner and are in row/column (i.e. y/x) order. So the values you get are transposed, upside down and shifted by one pixel. |
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May 7 |
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Why is arithmetic faster for inexact arithmetic? At least for inexact arithmetic, I'm pretty sure Mathematica never looks for the roots of a polynomial (because that's not numerically stable). It probably uses an iterative method like Jacobi's. |
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May 7 |
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Does LinearModelFit perform an ordinary linear regression (least squares)? Is there a reason why you use RandomReal[NormalDistribution[] instead of RandomVariate[NormalDistribution[], ? Can RandomReal work with any distribution? If yes, what's the point of RandomVariate anyway? |
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Apr 30 |
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How to compare graphical objects? What data do you have? A list of polygons? An image? A set of points? With or without outliers? Do you know point correspondences between the compared objects? Maybe FindGeometricTransform could help? |
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Apr 29 |
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How to compare graphical objects? Sort the lengths of the sides and compare them? |
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Apr 24 |
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looking for a generalised Hough Transform function or a least a function to locate circles @s.s.o: A hough transform can find circles even if they're not connected components (and circles detected e.g. using EdgeDetect are often not connected). But I think MMA has no built in generalized or circle hough transform. It would be relatively straightforward (but slow) to simulate it by convolving the image with circles with different radii. |
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Apr 22 |
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Get Coordinates in Image Processing +1. Instead of Dilation, you can use the ComponentMeasurements overload that takes a label matrix instead of an image: ComponentMeasurements[ImageData[Binarize[i]], "Centroid"]. That way, you'll always get a single component, because the label matrix only contains 0 and 1. |
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Apr 19 |
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Rotate a grid, made up of lines, so that it aligns with the xy axes +1. slope could be made shorter: slope[s_, e_] := ArcTan @@ (e - s) |
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Apr 18 |
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How to detect crosses and circles in 60x60 raster images? In general, ImageCorrelate and ComponentMeasurements might be worth a try. |
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Apr 18 |
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How to detect crosses and circles in 60x60 raster images? Can you add a few sample images, so potential answerers can test their answers? |
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Apr 17 |
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How to find the center of a circular pattern? Is the brightness always symmetrically distributed (as in the sample image you showed)? Then you could just calculate the center of mass of the (possibly thresholded or binarized) image. That's an O(N) operation instead of O(N Log(N)) for the FFT version. |
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Apr 6 |
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Cover a rectangle with size constrained rectangular regions And also here: stackoverflow.com/questions/15837871/… |
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Mar 22 |
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How to generate a matrix group? Maybe you could add a simple MemoryConstrained[...]? |
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Mar 20 |
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Why is this Mandelbrot set's implementation infeasible: takes a massive amount of time to do? @hhh: "0" is an exact number. "0." is a machine-precision number, and calculations with machine-precision numbers are much faster. |
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Feb 18 |
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Image processing: Floor plan - detecting rooms' borders (area) and room names' texts @s.s.o: That rectangle is not a room at all. It's an artifact of the segmentation used. You could e.g. remove every rectangle that doesn't touch a wall e.g. 50% of its border. Implementation should be straightforward and is left as an exercise to the reader ;-) |
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Feb 14 |
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Is it possible to do vector calculus in Mathematica? Related/possible duplicate: mathematica.stackexchange.com/questions/3242/… |
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Feb 13 |
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Image processing: Floor plan - detecting rooms' borders (area) and room names' texts @chris: I think the only new function is GeodesicDilation, right? You could get the same result using a combination of FixedPoint, Dilation and MapThread[Min, {dilation, mask},2]. Could be a lot slower, though. |
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Feb 12 |
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Finding the likeliest path in a Markov process Isn't that just what Viterbi's algorithm does? |
