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Horizon Smart Car Developer Community
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Guide
Horizon Smart Car Developer Community
Horizon Official Website
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Inverse Fast Fourier Transform 2D

The Inverse Fast Fourier Transform 2D (hereinafter referred to as IFFT2D) is a fast algorithm derived from the Inverse Fast Fourier Transform (hereinafter referred to as IFFT). It efficiently converts two-dimensional data from the frequency domain to the time domain, commonly employed for the restoration of images and other two-dimensional frequency domain data to their original time domain representation.

Operator Effect

Time Domain Input DataParameterFrequency Domain Output Data
imagep_size = HB_HPL_FFT16
normalize = 0
dataType = HB_HPL_DATA_TYPE_I16
imFormat = HB_IM_FORMAT_SEPARATE
numDimensionSize = 2		image

Principle

IFFT2D is an extension of the IFFT algorithm, designed to map frequency domain data to time domain data. It operates on two-dimensional data by performing IFFT operations separately along the y and x directions. The specific procedure is outlined as follows:

  1. Perform IFFT calculation on each column of the two-dimensional data, where ny represents the number of FFT points set in the interface parameters for the y-axis.
HPL5IFFT2D_y
  1. Building upon the processing in step 1, perform IFFT calculation on each row of the two-dimensional data, where nx represents the number of FFT points set in the interface parameters for the x-axis.
HPL5IFFT2D_x
  1. Return the calculation results from step 2.

API Interface

int32_t hbIFFT2D(hbUCPTaskHandle_t *taskHandle, hbHPLImaginaryData *dst, hbHPLImaginaryData const *src, hbIFFT2DParam const *param);

For detailed interface information, please refer to hbIFFT2D。

Usage

// Include the header #include "hobot/hb_ucp.h" #include "hobot/hpl/hb_hpl.h" #include "hobot/hpl/hb_ifft_2d.h" // init, allocate memory for data src_length = 1024 * 1024 * 5; hbUCPMallocCached(&src_re_mem, src_length, 0); hbUCPMallocCached(&src_im_mem, src_length, 0); hbHPLImaginaryData src; src.realDataVirAddr = src_re_mem.virAddr; src.realDataPhyAddr = src_re_mem.phyAddr; src.imDataVirAddr = src_im_mem.virAddr; src.imDataPhyAddr = src_im_mem.phyAddr; src.numDimensionSize = 2; src.dataType = HB_HPL_DATA_TYPE_I16; src.imFormat = HB_IM_FORMAT_SEPARATE; src.dimensionSize[0] = 16 * 11; src.dimensionSize[1] = 32 * 2; hbUCPMallocCached(&dst_re_mem, src_length, 0); hbUCPMallocCached(&dst_im_mem, src_length, 0); hbHPLImaginaryData dst; dst.realDataVirAddr = dst_re_mem.virAddr; dst.realDataPhyAddr = dst_re_mem.phyAddr; dst.imDataVirAddr = dst_im_mem.virAddr; dst.imDataPhyAddr = dst_im_mem.phyAddr; dst.numDimensionSize = 2; dst.dataType = HB_HPL_DATA_TYPE_I16; dst.imFormat = HB_IM_FORMAT_SEPARATE; dst.dimensionSize[0] = 16 * 11; dst.dimensionSize[1] = 32 * 2; // init param hbIFFT2DParam param; param.nx = HB_FFT_POINT_SIZE_16; param.ny = HB_FFT_POINT_SIZE_32; param.normalize = 0; // init task handle and schedule param hbUCPTaskHandle_t task_handle{nullptr}; hbUCPSchedParam sched_param{...}; // create task hbIFFT2D(&task_handle, &dst, &src, &param); // submit task hbUCPSubmitTask(task_handle, &sched_param); // wait for task done hbUCPWaitTaskDone(task_handle, 0); // release task handle hbUCPReleaseTask(task_handle); // release memory hbUCPFree(&src_re_mem); hbUCPFree(&src_im_mem); hbUCPFree(&dst_re_mem); hbUCPFree(&dst_im_mem);