points_harrispoints_harrisPointsHarrispoints_harrisPointsHarrisPointsHarris extracts points of interest from an image. The Harris
operator is based upon the smoothed matrix
points_harrispoints_harrisPointsHarrispoints_harrisPointsHarrisPointsHarris uses a special implementation that is
optimized using SSE2 instructions if the system
parameter 'sse2_enable'"sse2_enable""sse2_enable""sse2_enable""sse2_enable""sse2_enable" is set to 'true'"true""true""true""true""true" (which is
default if SSE2 is available on your machine). This implementation is
slightly inaccurate compared to the pure C version due to numerical issues
(for 'byte' images the difference in RowRowRowRowRowrow and ColumnColumnColumnColumnColumncolumn is in
order of magnitude of 1.0e-5). If you prefer accuracy over performance
you can set 'sse2_enable'"sse2_enable""sse2_enable""sse2_enable""sse2_enable""sse2_enable" to 'false'"false""false""false""false""false" (using
set_systemset_systemSetSystemset_systemSetSystemSetSystem) before you call points_harrispoints_harrisPointsHarrispoints_harrisPointsHarrisPointsHarris. This way
points_harrispoints_harrisPointsHarrispoints_harrisPointsHarrisPointsHarris does not use SSE2 accelerations. Don't forget to set
'sse2_enable'"sse2_enable""sse2_enable""sse2_enable""sse2_enable""sse2_enable" back to 'true'"true""true""true""true""true" afterwards.
points_harrispoints_harrisPointsHarrispoints_harrisPointsHarrisPointsHarris can be executed on an OpenCL device if both
SigmaGradSigmaGradSigmaGradSigmaGradSigmaGradsigmaGrad and SigmaSmoothSigmaSmoothSigmaSmoothSigmaSmoothSigmaSmoothsigmaSmooth induce a filter size of no more
than 129 pixels. This corresponds to a value of less than 20.7 for
both parameters. As with the SSE2 version, the results of the OpenCL
implementation may diverge slightly from that of pure C version due to
numerical issues.
Note that filter operators may return unexpected results if
an image with a reduced domain is used as input. Please refer to the
chapter Filters.
C. Harris, M. Stephens: “A combined corner and edge
detector”. Proceedings of the 4th Alvey Vision Conference,
pp. 147-151, 1988.
V. Gouet, N.Boujemaa: “Object-based queries using color points of
interest”. IEEE Workshop on Content-Based Access of Image and Video
Libraries, CVPR/CBAIVL 2001, Hawaii, USA, 2001.