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20h
comment Why is my compiled code slower?
Nice work untangling those loops! Any particular reason not to use IdentityMatrix[{J, n}] ?
21h
answered Probable Bug in HighlightMesh with 2D Convex Hulls created via ConvexHullMesh
1d
comment Speed up adding Poisson noise to an image
You mention speeding up the initial run of the code, and that it's a shame that PoissonDistribution can't be compiled. In fact the delay on the initial run is caused by compiling code to provide the Poisson distribution :-) You can look at Image`ColorOperationsDump`iImageEffectPoissonNoise to see how it works internally.
1d
comment Speed up adding Poisson noise to an image
@rasher, as blochwave correctly states, the distribution parameter depends on the individual pixel values so you can't simply generate a whole array of random values from a single distribution.
1d
comment Speeding Up Image Processing Functions
I don't think there is much you can do to speed up the built-in WatershedComponents. It is implemented using a separate program ITK.exe which I assume is an implementation of the ITK toolkit. I suspect paw's suggestion to use GPU processing might be the best approach to getting performance fast enough for a dynamic interface. A Google search for watershed components gpu gets some interesting looking results.
2d
comment Automatically lining up two images that have some common elements
@Mr.Wizard, I made an attempt at doing what you describe by doing correlations on smaller sub-images to get a local translation which varies across the image, then interpolating that data and using ImageForwardTransformation to apply the warp. It didn't work very well though.
Jul
28
comment why the variable scope is not local when using evaluate to plot multicurve?
For this reason it is better to use the option Evaluated -> True instead of Evaluate
Jul
28
comment Interpolation function rejected by ParametricPlot3D
I think it is just an accident that Mathematica manages to correctly interpret the unsupported syntax in some cases.
Jul
28
comment Interpolation function rejected by ParametricPlot3D
y[t] /. bally is a list. Use y[t] /. First[bally] to extract the actual interpolating function.
Jul
26
comment Possible bug in Dynamic
+1 Nice troubleshooting. Wrapping the ContourPlot in PreemptProtect seems to work too.
Jul
26
comment TrueQ returning False on true statement
TrueQ[Log[2]/Log[8] == 1/3] returns True with version 10 on Windows 7.
Jul
25
answered How to transpose x and y axes on a LogPlot?
Jul
25
awarded  Nice Answer
Jul
24
awarded  Nice Answer
Jul
24
revised Is there a way to recreate the typical Red/Blue-Postereffect using Mathematica?
edited body
Jul
24
comment Is there a way to recreate the typical Red/Blue-Postereffect using Mathematica?
@rm-rf, oh - so I did. Thanks.
Jul
24
answered Mapping with Trace[]
Jul
24
comment Mapping with Trace[]
{r1, r2} is evaluated first, so the symbols are replaced by their values before Trace sees them.
Jul
24
comment Is there a way to use video codecs for avi files in Mathematica?
g3kk0, just to be clear, are you saying that you get uncompressed AVI regardless of which codec you select? This is (obviously) incorrect behaviour - I suggest stating your OS and QuickTime version in the question so that others with the same setup can comment on whether they see the same problem.
Jul
24
comment Is there a way to use video codecs for avi files in Mathematica?
@Mr.Wizard, annoyingly there is support in Media Foundation for an AVI media sink but only for Windows 8.1.