added cv::calcBackProject for 2-dimensional histograms

modules/imgproc/src/histogram.cpp

@@ -1942,7 +1942,7 @@ static void getUMatIndex(const std::vector<UMat> & um, int cn, int & idx, int &
 
         if (totalChannels >= cn)
         {
-            idx = i;
+            idx = (int)i;
             cnidx = i == 0 ? cn : cn % (totalChannels - ccn);
             return;
         }
@@ -1966,7 +1966,7 @@ static bool ocl_calcBackProject( InputArrayOfArrays _images, std::vector<int> ch
     for (size_t i = 1; i < nimages; ++i)
     {
         const UMat & m = images[i];
-        totalcn *= m.channels();
+        totalcn += m.channels();
         CV_Assert(size == m.size() && depth == m.depth());
     }
 
@@ -1981,7 +1981,7 @@ static bool ocl_calcBackProject( InputArrayOfArrays _images, std::vector<int> ch
         CV_Assert(idx >= 0);
         UMat im = images[idx];
 
-        String opts = format("-D histdims=1 -D scn=%d", im.channels(), cnidx);
+        String opts = format("-D histdims=1 -D scn=%d", im.channels());
         ocl::Kernel lutk("calcLUT", ocl::imgproc::calc_back_project_oclsrc, opts);
         if (lutk.empty())
             return false;
@@ -2013,28 +2013,47 @@ static bool ocl_calcBackProject( InputArrayOfArrays _images, std::vector<int> ch
         int idx0, idx1, cnidx0, cnidx1;
         getUMatIndex(images, channels[0], idx0, cnidx0);
         getUMatIndex(images, channels[1], idx1, cnidx1);
-        printf("%d) channels = %d, indx = %d, cnidx = %d\n", images[0].channels(), channels[0], idx0, cnidx0);
-        printf("%d) channels = %d, indx = %d, cnidx = %d\n", images[1].channels(), channels[1], idx1, cnidx1);
         CV_Assert(idx0 >= 0 && idx1 >= 0);
         UMat im0 = images[idx0], im1 = images[idx1];
 
-        String opts = format("-D histdims=2 -D scn0=%d -D scn1=%d",
-                             im0.channels(), im1.channels());
-        ocl::Kernel k("calcBackProject", ocl::imgproc::calc_back_project_oclsrc, opts);
-        if (k.empty())
+        // Lut for the first dimension
+        String opts = format("-D histdims=2 -D scn1=%d -D scn2=%d", im0.channels(), im1.channels());
+        ocl::Kernel lutk1("calcLUT", ocl::imgproc::calc_back_project_oclsrc, opts);
+        if (lutk1.empty())
+            return false;
+
+        size_t lsize = 256;
+        UMat lut(1, (int)lsize<<1, CV_32SC1), uranges(ranges, true), hist = _hist.getUMat();
+
+        lutk1.args(hist.rows, ocl::KernelArg::PtrWriteOnly(lut), (int)0, ocl::KernelArg::PtrReadOnly(uranges), (int)0);
+        if (!lutk1.run(1, &lsize, NULL, false))
+            return false;
+
+        // lut for the second dimension
+        ocl::Kernel lutk2("calcLUT", ocl::imgproc::calc_back_project_oclsrc, opts);
+        if (lutk2.empty())
+            return false;
+
+        lut.offset += lsize * sizeof(int);
+        lutk2.args(hist.cols, ocl::KernelArg::PtrWriteOnly(lut), (int)256, ocl::KernelArg::PtrReadOnly(uranges), (int)2);
+        if (!lutk2.run(1, &lsize, NULL, false))
+            return false;
+
+        // perform lut
+        ocl::Kernel mapk("LUT", ocl::imgproc::calc_back_project_oclsrc, opts);
+        if (mapk.empty())
             return false;
 
         _dst.create(size, depth);
-        UMat dst = _dst.getUMat(), hist = _hist.getUMat(), uranges(ranges, true);
+        UMat dst = _dst.getUMat();
 
         im0.offset += cnidx0;
         im1.offset += cnidx1;
-        k.args(ocl::KernelArg::ReadOnlyNoSize(im0), ocl::KernelArg::ReadOnlyNoSize(im1),
-               ocl::KernelArg::ReadOnly(hist), ocl::KernelArg::WriteOnly(dst), scale,
-               ocl::KernelArg::PtrReadOnly(uranges));
+        mapk.args(ocl::KernelArg::ReadOnlyNoSize(im0), ocl::KernelArg::ReadOnlyNoSize(im1),
+               ocl::KernelArg::ReadOnlyNoSize(hist), ocl::KernelArg::PtrReadOnly(lut), scale, ocl::KernelArg::WriteOnly(dst));
 
         size_t globalsize[2] = { size.width, size.height };
-        return k.run(2, globalsize, NULL, false);
+        return mapk.run(2, globalsize, NULL, false);
     }
     return false;
 }
@@ -2051,12 +2070,9 @@ void cv::calcBackProject( InputArrayOfArrays images, const std::vector<int>& cha
     size_t histdims = _1D ? 1 : hist.dims();
 
     if (ocl::useOpenCL() && images.isUMatVector() && dst.isUMat() && hist.type() == CV_32FC1 &&
-            histdims <= 2 && ranges.size() == histdims * 2 && histdims == channels.size() /*&&
-            ocl_calcBackProject(images, channels, hist, dst, ranges, scale)*/)
-    {
-        CV_Assert(ocl_calcBackProject(images, channels, hist, dst, ranges, (float)scale, histdims));
+            histdims <= 2 && ranges.size() == histdims * 2 && histdims == channels.size() &&
+            ocl_calcBackProject(images, channels, hist, dst, ranges, (float)scale, histdims))
         return;
-    }
 
     Mat H0 = hist.getMat(), H;
     int hcn = H0.channels();

modules/imgproc/src/opencl/calc_back_project.cl

@@ -37,10 +37,10 @@
 //
 //
 
-#if histdims == 1
-
 #define OUT_OF_RANGE -1
 
+#if histdims == 1
+
 __kernel void calcLUT(__global const uchar * histptr, int hist_step, int hist_offset, int hist_bins,
                       __global int * lut, float scale, __constant float * ranges)
 {
@@ -68,7 +68,7 @@ __kernel void calcLUT(__global const uchar * histptr, int hist_step, int hist_of
 }
 
 __kernel void LUT(__global const uchar * src, int src_step, int src_offset,
-                  __global const int * lut,
+                  __constant int * lut,
                   __global uchar * dst, int dst_step, int dst_offset, int dst_rows, int dst_cols)
 {
     int x = get_global_id(0);
@@ -86,45 +86,47 @@ __kernel void LUT(__global const uchar * src, int src_step, int src_offset,
 
 #elif histdims == 2
 
-#define OUT_OF_RANGES(i) ( (value##i > ranges[(i<<1)+1]) || (value##i < ranges[i<<1]) )
-#define CALCULATE_BIN(i) \
-    float lb##i = ranges[i<<1], ub##i = ranges[(i<<1)+1], gap##i = (ub##i - lb##i) / hist_bins##i; \
-    value##i -= ranges[i<<1]; \
-    int bin##i = convert_int_sat_rtn(value##i / gap##i)
-
-__kernel void calcBackProject(__global const uchar * src0, int src0_step, int src0_offset,
-                              __global const uchar * src1, int src1_step, int src1_offset,
-                              __global const uchar * histptr, int hist_step, int hist_offset, int hist_bins0, int hist_bins1,
-                              __global uchar * dst, int dst_step, int dst_offset, int dst_rows, int dst_cols,
-                              float scale, __constant float * ranges)
+__kernel void calcLUT(int hist_bins, __global int * lut, int lut_offset,
+                      __constant float * ranges, int roffset)
+{
+    int x = get_global_id(0);
+    float value = convert_float(x);
+
+    ranges += roffset;
+    lut += lut_offset;
+
+    if (value > ranges[1] || value < ranges[0])
+        lut[x] = OUT_OF_RANGE;
+    else
+    {
+        float lb = ranges[0], ub = ranges[1], gap = (ub - lb) / hist_bins;
+        value -= lb;
+        int bin = convert_int_sat_rtn(value / gap);
+
+        lut[x] = bin >= hist_bins ? OUT_OF_RANGE : bin;
+    }
+}
+
+__kernel void LUT(__global const uchar * src1, int src1_step, int src1_offset,
+                  __global const uchar * src2, int src2_step, int src2_offset,
+                  __global const uchar * histptr, int hist_step, int hist_offset,
+                  __constant int * lut, float scale,
+                  __global uchar * dst, int dst_step, int dst_offset, int dst_rows, int dst_cols)
 {
     int x = get_global_id(0);
     int y = get_global_id(1);
 
     if (x < dst_cols && y < dst_rows)
     {
-        int src0_index = mad24(src0_step, y, src0_offset + x * scn0);
-        int src1_index = mad24(src1_step, y, src1_offset + x * scn1);
-        int dst_index = mad24(dst_step, y, dst_offset + x);
+        int src1_index = mad24(y, src1_step, src1_offset + x * scn1);
+        int src2_index = mad24(y, src2_step, src2_offset + x * scn2);
+        int dst_index = mad24(y, dst_step, dst_offset + x);
 
-        float value0 = convert_float(src0[src0_index]), value1 = convert_float(src1[src1_index]);
-        if (OUT_OF_RANGES(0) || OUT_OF_RANGES(1))
-            dst[dst_index] = 0;
-        else
-        {
-            CALCULATE_BIN(0);
-            CALCULATE_BIN(1);
-
-            if (bin0 >= hist_bins0 || bin1 >= hist_bins1)
-                dst[dst_index] = 0;
-            else
-            {
-                int hist_index = mad24(hist_step, bin0, hist_offset + bin1 * (int)sizeof(float));
-                __global const float * hist = (__global const float *)(histptr + hist_index);
-
-                dst[dst_index] = convert_uchar_sat_rte(scale * hist[0]);
-            }
-        }
+        int bin1 = lut[src1[src1_index]];
+        int bin2 = lut[src2[src2_index] + 256];
+        dst[dst_index] = bin1 == OUT_OF_RANGE || bin2 == OUT_OF_RANGE ? 0 :
+                        convert_uchar_sat_rte(*(__global const float *)(histptr +
+                        mad24(hist_step, bin1, hist_offset + bin2 * (int)sizeof(float))) * scale);
     }
 }
 

modules/imgproc/test/ocl/test_histogram.cpp

@@ -147,15 +147,6 @@ PARAM_TEST_CASE(CalcBackProject, MatDepth, int, bool)
 
     void Near()
     {
-//        std::cout << "Src: " << std::endl << src_roi[0] << std::endl;
-//        std::cout << "Hist: " << std::endl << hist_roi << std::endl;
-        std::cout << "OpenCV: " << std::endl << dst_roi << std::endl;
-        std::cout << "OpenCL: " << std::endl << udst_roi.getMat(ACCESS_READ) << std::endl;
-
-        Mat diff;
-        cv::absdiff(dst_roi, udst_roi, diff);
-        std::cout << "Difference: " << std::endl << diff << std::endl;
-
         OCL_EXPECT_MATS_NEAR(dst, 0.0)
     }
 };