.. _program_listing_file__tmp_ws_src_vitis_common_include_imgproc_xf_otsuthreshold.hpp:

Program Listing for File xf_otsuthreshold.hpp
=============================================

|exhale_lsh| :ref:`Return to documentation for file <file__tmp_ws_src_vitis_common_include_imgproc_xf_otsuthreshold.hpp>` (``/tmp/ws/src/vitis_common/include/imgproc/xf_otsuthreshold.hpp``)

.. |exhale_lsh| unicode:: U+021B0 .. UPWARDS ARROW WITH TIP LEFTWARDS

.. code-block:: cpp

   /*
    * Copyright 2019 Xilinx, Inc.
    *
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    *     http://www.apache.org/licenses/LICENSE-2.0
    *
    * Unless required by applicable law or agreed to in writing, software
    * distributed under the License is distributed on an "AS IS" BASIS,
    * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    * See the License for the specific language governing permissions and
    * limitations under the License.
    */
   
   #ifndef _XF_OTSUTHRESHOLD_HPP_
   #define _XF_OTSUTHRESHOLD_HPP_
   
   #include "../common/xf_types.hpp"
   #include "../core/xf_math.h"
   #include "xf_histogram.hpp"
   
   namespace xf {
   namespace cv {
   
   static void xfOtsuKernel(uint32_t _hist[0][256], uint16_t _height, uint16_t _width, uint8_t& thresh) {
   // clang-format off
       #pragma HLS INLINE off
       // clang-format on
   
       ap_uint<33> HistArray[256] = {0};
       ap_uint<45> tmp1, tmp2;
   
       ap_uint<25> total;
       uint8_t max_val = 0;
       unsigned int sum = 0;
   
       unsigned short int cols = _width;
       unsigned short int rows = _height;
   
       char shift1 = 0, shift2 = 0;
       char shift3, shift4;
   
       unsigned int wB = 0;
       unsigned int wF = 0;
       unsigned long long int sumB = 0;
       unsigned long long int varMax = 0;
   
       unsigned int wdt = xf::cv::Inverse(cols, 16, &shift1); // Q0.24
       unsigned int hgt = xf::cv::Inverse(rows, 16, &shift2); // Q0.24
       char n1, n2;
       if (shift1 > 24) {
           wdt = wdt >> (shift1 - 24);
           shift1 = 24;
       } else if (((shift1 >> 1) << 1) != shift1) {
           wdt = wdt << (24 - shift1);
           shift1 = 24;
       }
       if (shift2 > 24) {
           hgt = hgt >> (shift2 - 24);
           shift2 = 24;
       } else if (((shift2 >> 1) << 1) != shift2) {
           hgt = hgt << (24 - shift2);
           shift2 = 24;
       }
       shift3 = shift1 >> 1;
       shift4 = shift2 >> 1;
   
       tmp1 = (cols * wdt) >> shift3; // Q0.12
       tmp2 = (rows * hgt) >> shift4; // Q0.12
       total = tmp1 * tmp2;           // Q0.25
   
   HISTOGRAM_NORM_LOOP:
       for (uint16_t i = 0; i < 256; i++) {
   // clang-format off
           #pragma HLS PIPELINE
           // clang-format on
           tmp1 = (ap_uint<45>)_hist[0][i];
           tmp2 = (tmp1 * wdt) >> shift3;
           HistArray[i] = (tmp2 * hgt) >> shift4; // Histogram array is expressed in Q8.25
       }
   SUM_LOOP:
       for (uint16_t i = 0; i < 256; i++) {
   // clang-format off
           #pragma HLS PIPELINE
           // clang-format on
           sum = sum + i * HistArray[i]; // sum is expressed in Q8.24
       }
   
   THRESHOLD_LOOP:
       for (uint16_t i = 0; i < 256; i++) {
   // clang-format off
           #pragma HLS LOOP_TRIPCOUNT  min=256 max=256
           #pragma HLS PIPELINE
           // clang-format on
           wB = wB + HistArray[i]; // wB is expressed in Q0.25
           if (wB > 0) {
               if ((wB >> (shift3 + shift4)) == 1) break;
               wF = total - wB;                // wF is expressed in Q0.25
               sumB = sumB + HistArray[i] * i; // sumB is expressed in Q8.24
               unsigned int b = (wF + wB);     // b is expressed in Q0.25
   
               long long int a1 = (sumB * b) >> (shift3 + shift4); // a1 is expressed in Q8.25
   
               long long int c1 = ((long long int)sum * wB) >> (shift3 + shift4); // c1 is expressed in Q8.25
               long long int d = a1 - c1;
               d = __ABS(d);
   
               unsigned int res = (d * d) >> (shift3 + shift4 + 10); // res is expressed in Q16.16
   
               unsigned short int x_inv1 = (unsigned short int)(wB >> 9);
               unsigned short int x_inv2 = (unsigned short int)(wF >> 9);
   
               unsigned int val1 = xf::cv::Inverse(x_inv1, 0, &n1);
               unsigned int val2 = xf::cv::Inverse(x_inv2, 0, &n2);
   
               unsigned long long int maxtmp =
                   (unsigned long long int)((unsigned long long int)res * (unsigned long long int)val1) >> n1;
               unsigned long long max = (maxtmp * (unsigned long long)val2) >> n2;
   
               if (max > varMax) {
                   varMax = max;
                   max_val = i;
               }
           }
       }
   
       thresh = max_val;
   }
   
   /*********************************************************************
    * Otsuthreshold : Computes the otsu threshold for the input image
    *********************************************************************/
   
   template <int SRC_T, int ROWS, int COLS, int NPC = 1>
   void OtsuThreshold(xf::cv::Mat<SRC_T, ROWS, COLS, NPC>& _src_mat, uint8_t& _thresh) {
   #ifndef __SYNTHESIS__
       assert(((NPC == XF_NPPC1) || (NPC == XF_NPPC8)) && "NPC must be XF_NPPC1, XF_NPPC8 ");
       assert(((_src_mat.rows <= ROWS) && (_src_mat.cols <= COLS)) && "ROWS and COLS should be greater than input image");
   #endif
   
       uint32_t hist[XF_CHANNELS(SRC_T, NPC)][256];
       uint8_t thresh;
   
   // clang-format off
       #pragma HLS INLINE off
       #pragma HLS interface ap_fifo port=hist
       // clang-format on
   
       uint16_t width = _src_mat.cols >> (XF_BITSHIFT(NPC));
       uint16_t height = _src_mat.rows;
   
       xFHistogramKernel<SRC_T, ROWS, COLS, XF_DEPTH(SRC_T, NPC), NPC, XF_WORDWIDTH(SRC_T, NPC),
                         ((COLS >> (XF_BITSHIFT(NPC))) >> 1), XF_CHANNELS(SRC_T, NPC)>(_src_mat, hist, height, width);
   
       xfOtsuKernel(hist, height, _src_mat.cols, thresh);
       _thresh = thresh;
   }
   } // namespace cv
   } // namespace xf
   
   #endif //