optimize_fft_speed — Optimize the runtime of the FFT.
optimize_fft_speed determines a method that achieves an optimum runtime of the FFT for an image of size Width x Height. The data that are determined for one image size do not influence the methods used for other image sizes. Consequently, optimize_fft_speed can be called multiple times with different values for Width and Height to achieve an optimum runtime for all image sizes that are used in an application. The parameter Mode determines the thoroughness of the search for the fastest method. For Mode = '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 Mode = 'patient' a more thorough search is performed, which typically takes several seconds and in most cases leads to optimum runtimes. For Mode = 'exhaustive' an exhaustive search is performed, which typically takes several minutes and always results in the optimum runtime. In most applications, Mode = '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_speed can be saved with write_fft_optimization_data and can be loaded with read_fft_optimization_data.
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_speed influences the runtime of the following operators, which use the FFT: fft_generic, fft_image, fft_image_inv, photometric_stereo, sfs_pentland, sfs_mod_lr, sfs_orig_lr.
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
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
Thoroughness of the search for the optimum runtime.
Default value: 'standard'
List of values: 'exhaustive', 'patient', 'standard'
optimize_fft_speed returns 2 (H_MSG_TRUE) if all parameters are correct. If necessary, an exception is raised.
fft_generic, fft_image, fft_image_inv, wiener_filter, wiener_filter_ni, photometric_stereo, sfs_pentland, sfs_mod_lr, sfs_orig_lr, write_fft_optimization_data