Notes
(0017079) Hans Johnson (developer) 2009-08-06 23:40	The itkSparseFreqeuncyContainer, and the itkDenseFrequenceyContainer are using floating point values for their FrequencyType. In many common images of size 512x512x384 have backgrounds of all zeros with a count greater than the maximum that can be incremented to using 32 bit floating point numbers.

(0017081) Bradley Lowekamp (developer) 2009-08-07 08:54	From: blowekamp@mail.nih.gov Subject: Re: [Insight-developers] Limits of Histograms' FrequencyType Date: October 22, 2008 8:12:05 AM CDT To: insight-developers@itk.org The problem with creating a a double DenseFrequencyContainer is that the Histogram class with then have conflicting types for it's FrequencyType, one from the container the other from the Superclass, SampleType. This created problems with at least one virtual function. Another possible solution would be just to improve the algorithm in ListSampleToHistogramGenerator so that if there is over 2^24 samples then it would chunk it up and use an iterative total histogram + accumulator histogram. This would only cause a small loss of precision but would give reasonable results. Perhaps this would also give an opportunity to parallelize this part too. On Oct 21, 2008, at 2:50 PM, Bradley Lowekamp wrote: Hello, I am causing trouble with my large data sets again. I am seeing this number a lot in my histograms: 1.67772e+07 which is 2^24 and the limit of mantissa for 32-bit floats. Unfortunately, the frequency container types don't take this as a template parameter. It seems silly to create another container just for this purpose. Brad ----------------- I made simular changed to the DenseFrequency container before. If I recall correctly I also had to change itkSample with: typedef float FrequencyType; because the frequency type was defined differently in the itkSample and itkHistogram

(0017087) Luis Ibanez (manager) 2009-08-08 14:40	Added verification for saturation of the Frequency counters, both for the frequency of the instance and for the total frequency: http://public.kitware.com/cgi-bin/viewcvs.cgi/Code/Numerics/Statistics/itkSparseFrequencyContainer.cxx?root=Insight&r1=1.5&r2=1.6&sortby=date [^] http://public.kitware.com/cgi-bin/viewcvs.cgi/Code/Numerics/Statistics/itkDenseFrequencyContainer.cxx?root=Insight&r1=1.4&r2=1.5&sortby=date [^] This doesn't fix the bug, but at least provides a reasonable way of reporting the incorrect behavior of the frequency container.

(0017098) Hans Johnson (developer) 2009-08-11 18:44	Luis, I don't think your fix is going to work. Where FrequencyType=float NumericTraits< FrequencyType >::max() is much greater than http://en.wikipedia.org/wiki/Floating_point [^] Any integer with absolute value less than or equal to 2^24 can be exactly represented in the single precision format 2^24=16777216 Code that will fail after 16777216 #include <iostream> int main (int argc, char *argv[]) { size_t myint=0; float myfloat=0; do { myint+=1; myfloat+=1; } while(myint == static_cast<size_t>(myfloat) ); std::cout << myint << " does not equal " << static_cast<size_t>(myfloat) << std::endl; return 0; } 16777217 does not equal 16777216 Where NumericTraits< FrequencyType >::max() = 3.403 x 10^38

(0018813) Hans Johnson (developer) 2009-12-11 08:09	Luis, This did not have anyone assigned to it. Since you had made comments and some initial attempts of looking at this, I've assigned it to you so that it has a proper home. Hans

(0021677) Hans Johnson (developer) 2010-08-05 21:05	I don't think this bug is relevant in the new statistics framework.

(0022998) Luis Ibanez (manager) 2010-11-07 02:08	not relevant for the new statistics framework in ITKv4

Issue History
Date Modified	Username	Field	Change
2009-08-06 23:36	Hans Johnson	New Issue
2009-08-06 23:40	Hans Johnson	Note Added: 0017079
2009-08-07 08:54	Bradley Lowekamp	Note Added: 0017081
2009-08-08 14:40	Luis Ibanez	Note Added: 0017087
2009-08-11 18:44	Hans Johnson	Note Added: 0017098
2009-12-11 08:06	Hans Johnson	Status	new => assigned
2009-12-11 08:06	Hans Johnson	Assigned To	=> Hans Johnson
2009-12-11 08:09	Hans Johnson	Note Added: 0018813
2009-12-16 08:23	Hans Johnson	Assigned To	Hans Johnson => Luis Ibanez
2010-08-05 21:05	Hans Johnson	Note Added: 0021677
2010-11-07 02:08	Luis Ibanez	Sprint Status	=> backlog
2010-11-07 02:08	Luis Ibanez	Note Added: 0022998
2010-11-07 02:08	Luis Ibanez	Status	assigned => closed
2010-11-07 02:08	Luis Ibanez	Resolution	open => fixed

Relationships