cv::equalizeHist

modules/imgproc/src/histogram.cpp

@@ -3430,24 +3430,40 @@ namespace cv {
 
 static bool ocl_equalizeHist(InputArray _src, OutputArray _dst)
 {
-    size_t wgs = std::min<size_t>(ocl::Device::getDefault().maxWorkGroupSize(), BINS);
+    const ocl::Device & dev = ocl::Device::getDefault();
+    int compunits = dev.maxComputeUnits();
+    size_t wgs = dev.maxWorkGroupSize();
+    Size size = _src.size();
+    bool use16 = size.width % 16 == 0 && _src.offset() % 16 == 0 && _src.step() % 16 == 0;
+    int kercn = dev.isAMD() && use16 ? 16 : std::min(4, ocl::predictOptimalVectorWidth(_src));
 
-    // calculation of histogram
-    UMat hist;
-    if (!ocl_calcHist1(_src, hist))
+    ocl::Kernel k1("calculate_histogram", ocl::imgproc::histogram_oclsrc,
+                   format("-D BINS=%d -D HISTS_COUNT=%d -D WGS=%d -D kercn=%d -D T=%s%s",
+                          BINS, compunits, wgs, kercn,
+                          kercn == 4 ? "int" : ocl::typeToStr(CV_8UC(kercn)),
+                          _src.isContinuous() ? " -D HAVE_SRC_CONT" : ""));
+    if (k1.empty())
         return false;
 
-    UMat lut(1, 256, CV_8UC1);
-    ocl::Kernel k("calcLUT", ocl::imgproc::histogram_oclsrc,
-                  format("-D BINS=%d -D HISTS_COUNT=1 -D WGS=%d", BINS, (int)wgs));
-    if (k.empty())
+    UMat src = _src.getUMat(), ghist(1, BINS * compunits, CV_32SC1);
+
+    k1.args(ocl::KernelArg::ReadOnly(src),
+            ocl::KernelArg::PtrWriteOnly(ghist), (int)src.total());
+
+    size_t globalsize = compunits * wgs;
+    if (!k1.run(1, &globalsize, &wgs, false))
         return false;
 
-    k.args(ocl::KernelArg::PtrWriteOnly(lut),
-           ocl::KernelArg::PtrReadOnly(hist), (int)_src.total());
+    wgs = std::min<size_t>(ocl::Device::getDefault().maxWorkGroupSize(), BINS);
+    UMat lut(1, 256, CV_8UC1);
+    ocl::Kernel k2("calcLUT", ocl::imgproc::histogram_oclsrc,
+                  format("-D BINS=%d -D HISTS_COUNT=%d -D WGS=%d",
+                         BINS, compunits, (int)wgs));
+    k2.args(ocl::KernelArg::PtrWriteOnly(lut),
+           ocl::KernelArg::PtrReadOnly(ghist), (int)_src.total());
 
     // calculation of LUT
-    if (!k.run(1, &wgs, &wgs, false))
+    if (!k2.run(1, &wgs, &wgs, false))
         return false;
 
     // execute LUT transparently

modules/imgproc/src/opencl/histogram.cl

@@ -153,13 +153,37 @@ __kernel void merge_histogram(__global const int * ghist, __global uchar * histp
 #endif
 }
 
-__kernel void calcLUT(__global uchar * dst, __constant int * hist, int total)
+__kernel void calcLUT(__global uchar * dst, __global const int * ghist, int total)
 {
     int lid = get_local_id(0);
     __local int sumhist[BINS];
     __local float scale;
 
-    sumhist[lid] = hist[lid];
+#if WGS >= BINS
+    int res = 0;
+#else
+    #pragma unroll
+    for (int i = lid; i < BINS; i += WGS)
+        sumhist[i] = 0;
+#endif
+
+    #pragma unroll
+    for (int i = 0; i < HISTS_COUNT; ++i)
+    {
+        #pragma unroll
+        for (int j = lid; j < BINS; j += WGS)
+#if WGS >= BINS
+            res += ghist[j];
+#else
+            sumhist[j] += ghist[j];
+#endif
+        ghist += BINS;
+    }
+
+#if WGS >= BINS
+    if (lid < BINS)
+        sumhist[lid] = res;
+#endif
     barrier(CLK_LOCAL_MEM_FENCE);
 
     if (lid == 0)