optimize_fft_speedoptimize_fft_speedOptimizeFftSpeedOptimizeFftSpeed (Operator)

Name

optimize_fft_speedoptimize_fft_speedOptimizeFftSpeedOptimizeFftSpeed — Optimize the runtime of the FFT.

Signature

optimize_fft_speed( : : Width, Height, Mode : )

optimize_fft_speedoptimize_fft_speedOptimizeFftSpeedOptimizeFftSpeedOptimizeFftSpeed determines a method that achieves an optimum runtime of the FFT for an image of size WidthWidthWidthWidthwidth x HeightHeightHeightHeightheight. The data that are determined for one image size do not influence the methods used for other image sizes. Consequently, optimize_fft_speedoptimize_fft_speedOptimizeFftSpeedOptimizeFftSpeedOptimizeFftSpeed can be called multiple times with different values for WidthWidthWidthWidthwidth and HeightHeightHeightHeightheight to achieve an optimum runtime for all image sizes that are used in an application. The parameter ModeModeModeModemode determines the thoroughness of the search for the fastest method. For ModeModeModeModemode = 'standard'"standard""standard""standard""standard" a fast search is used, which typically takes a few seconds. The method thus determined results in very good runtimes, which are not always optimal. For ModeModeModeModemode = 'patient'"patient""patient""patient""patient" a more thorough search is performed, which typically takes several seconds and in most cases leads to optimum runtimes. For ModeModeModeModemode = 'exhaustive'"exhaustive""exhaustive""exhaustive""exhaustive" an exhaustive search is performed, which typically takes several minutes and always results in the optimum runtime. In most applications, ModeModeModeModemode = 'standard'"standard""standard""standard""standard" results in the best compromise between the runtime of the FFT and the time required for the search of the optimum runtime. The data determined with optimize_fft_speedoptimize_fft_speedOptimizeFftSpeedOptimizeFftSpeedOptimizeFftSpeed can be saved with write_fft_optimization_datawrite_fft_optimization_dataWriteFftOptimizationDataWriteFftOptimizationDataWriteFftOptimizationData and can be loaded with read_fft_optimization_dataread_fft_optimization_dataReadFftOptimizationDataReadFftOptimizationDataReadFftOptimizationData.

Please note that this optimization is performed for the particular computer on which the operator is called. The results are not suited to be transferred and used on other computers unless they have the same hardware and software configuration including the driver versions.

optimize_fft_speedoptimize_fft_speedOptimizeFftSpeedOptimizeFftSpeedOptimizeFftSpeed influences the runtime of the following operators, which use the FFT: fft_genericfft_genericFftGenericFftGenericFftGeneric, fft_imagefft_imageFftImageFftImageFftImage, fft_image_invfft_image_invFftImageInvFftImageInvFftImageInv, photometric_stereophotometric_stereoPhotometricStereoPhotometricStereoPhotometricStereo, sfs_pentlandsfs_pentlandSfsPentlandSfsPentlandSfsPentland, sfs_mod_lrsfs_mod_lrSfsModLrSfsModLrSfsModLr, sfs_orig_lrsfs_orig_lrSfsOrigLrSfsOrigLrSfsOrigLr.

Execution Information

Multithreading type: reentrant (runs in parallel with non-exclusive operators).
Multithreading scope: global (may be called from any thread).
Processed without parallelization.

Parameters

WidthWidthWidthWidthwidth (input_control) integer → (integer)

Width of the image for which the runtime should be optimized.

Default value: 512

Suggested values: 128, 160, 192, 256, 320, 384, 512, 640, 768, 1024, 2048

HeightHeightHeightHeightheight (input_control) integer → (integer)

Height of the image for which the runtime should be optimized.

Default value: 512

Suggested values: 120, 128, 144, 240, 256, 288, 480, 512, 576, 1024, 2048

ModeModeModeModemode (input_control) string → (string)

Thoroughness of the search for the optimum runtime.

Default value: 'standard' "standard" "standard" "standard" "standard"

List of values: 'exhaustive'"exhaustive""exhaustive""exhaustive""exhaustive", 'patient'"patient""patient""patient""patient", 'standard'"standard""standard""standard""standard"

Result

optimize_fft_speedoptimize_fft_speedOptimizeFftSpeedOptimizeFftSpeedOptimizeFftSpeed returns 2 (H_MSG_TRUE) if all parameters are correct. If necessary, an exception is raised.