Read 4 pixel for aligned data with 1 channel

modules/core/src/convert.cpp

@@ -1548,10 +1548,12 @@ static bool ocl_LUT(InputArray _src, InputArray _lut, OutputArray _dst)
     UMat src = _src.getUMat(), lut = _lut.getUMat();
     _dst.create(src.size(), CV_MAKETYPE(ddepth, dcn));
     UMat dst = _dst.getUMat();
+    bool bAligned = (1 == dcn) && (0 == (src.offset % 4)) && (0 == (src.cols % 4));
 
     ocl::Kernel k("LUT", ocl::core::lut_oclsrc,
-                  format("-D dcn=%d -D lcn=%d -D srcT=%s -D dstT=%s", dcn, lcn,
-                         ocl::typeToStr(src.depth()), ocl::memopTypeToStr(ddepth)
+                  format("-D dcn=%d -D lcn=%d -D srcT=%s -D dstT=%s%s", dcn, lcn,
+                         ocl::typeToStr(src.depth()), ocl::memopTypeToStr(ddepth),
+                         bAligned ? " -D USE_ALIGNED" : ""
                          ));
     if (k.empty())
         return false;
@@ -1560,6 +1562,8 @@ static bool ocl_LUT(InputArray _src, InputArray _lut, OutputArray _dst)
            ocl::KernelArg::WriteOnly(dst));
 
     size_t globalSize[2] = { dst.cols, (dst.rows + 3) / 4};
+    if (bAligned)
+        globalSize[0] = (dst.cols + 3) / 4;
     return k.run(2, globalSize, NULL, false);
 }
 

modules/core/src/opencl/lut.cl

@@ -57,10 +57,20 @@
             dst[0] = lut_l[idx->x];\
             dst[1] = lut_l[idx->y];
     #elif dcn == 1
-        #define LUT_OP(num)\
-            uchar idx = (srcptr + mad24(num, src_step, src_index))[0];\
-            dst = (__global dstT *)(dstptr + mad24(num, dst_step, dst_index));\
-            dst[0] = lut_l[idx];
+        #ifdef USE_ALIGNED
+            #define LUT_OP(num)\
+                int idx = *(__global const int *)(srcptr + mad24(num, src_step, src_index));\
+                dst = (__global dstT *)(dstptr + mad24(num, dst_step, dst_index));\
+                dst[0] = lut_l[idx & 0xff];\
+                dst[1] = lut_l[(idx >> 8) & 0xff];\
+                dst[2] = lut_l[(idx >> 16) & 0xff];\
+                dst[3] = lut_l[(idx >> 24) & 0xff];
+        #else
+            #define LUT_OP(num)\
+                uchar idx = (srcptr + mad24(num, src_step, src_index))[0];\
+                dst = (__global dstT *)(dstptr + mad24(num, dst_step, dst_index));\
+                dst[0] = lut_l[idx];
+        #endif
     #else
         #define LUT_OP(num)\
             src = (__global const srcT *)(srcptr + mad24(num, src_step, src_index));\
@@ -126,7 +136,11 @@ __kernel void LUT(__global const uchar * srcptr, int src_step, int src_offset,
     __local dstT lut_l[256 * lcn];
     LOCAL_LUT_INIT;
 
+#ifdef USE_ALIGNED
+    int x = 4 * get_global_id(0);
+#else
     int x = get_global_id(0);
+#endif
     int y = 4 * get_global_id(1);
 
     if (x < cols && y < rows)