HDR Decompanding - 2023.2 English

API Syntax

For imaging sensors that do not equip with high bit width in the transmission side, they can compress(compand) data in a piece-wise linear (PWL) mapping to a lower bit depth. The receiving end will do the inverse (or de-compand) to recover the data with satisfiable aliasing.

This implementaion supports Bayer Raw data with 4 knee points PWL mapping and default equations are provided for 12bit to 20bit and 16bit to 24bit conversion.

template <int SRC_T,
      int DST_T,
      int ROWS,
      int COLS,
      int NPC,
      int XFCVDEPTH_IN = _XFCVDEPTH_DEFAULT,
      int XFCVDEPTH_OUT = _XFCVDEPTH_DEFAULT>
void hdr_decompand(xf::cv::Mat<SRC_T, ROWS, COLS, NPC, XFCVDEPTH_IN>& src,
               xf::cv::Mat<DST_T, ROWS, COLS, NPC, XFCVDEPTH_OUT>& dst,
               int params[3][4][3],
               unsigned short bayerp)

The following table describes the template and the function parameters.

Table 523 Table HDR Decompand Parameter Description
Parameter	Description
SRC_T	Input Pixel type. The current supported pixel value is XF_16UC1
DST_T	Output Pixel type. The current supported pixel value is XF_32UC1
ROWS	Maximum height of the image that hardware kernel must be built for
COLS	Maximum width of the image that hardware kernel must be built for
NPC	Number of Pixels to be processed per cycle. NPPC1 and NPPC2 are supported.
XFCVDEPTH_IN	Depth of Input Image
XFCVDEPTH_OUT	Depth of Output Image
src	Input Image
dst	Output Image
params	array containing upper limit, slope and intercept of linear equations for Red, Green and Blue colours.
bayerp	Input Bayer pattern. XF_BAYER_BG, XF_BAYER_GB, XF_BAYER_GR and XF_BAYER_RG are the supported values.

Resource Utilization

The following table summarizes the resource utilization in different configurations, generated using Vitis HLS 2022.2 tool for the xcu200-fsgd2104-2-e, to process a FHD Bayer image.

Table 524 Table HDR Decompand Resource Utilization Summary
Operating Mode	Operating Frequency (MHz)	Utilization Estimate
Operating Mode	Operating Frequency (MHz)	BRAM_18K	DSP	FF	LUT	URAM
1 Pixel	300	0	9	473	296	0
2 Pixel	300	0	12	557	518	0

Performance Estimate

The following table summarizes the performance estimates in different configurations, generated using Vitis HLS 2022.2 tool for the xcu200-fsgd2104-2-e, to process a FHD Bayer image.

Table 525 Table HDR Decompand Performance Estimate Summary
Operating Mode	Operating Frequency (MHz)	Latency Estimate
Operating Mode	Operating Frequency (MHz)	Max (ms)
1 pixel	300	8.8
2 pixel	300	4.3