more optimization for warpAffine and warpPerspective

Add new OpenCL kernels for bicubic interploation, it is 20% faster
than current warp image kernel with bicubic interploation.
Signed-off-by: Li Peng <peng.li@intel.com>

modules/imgproc/src/imgwarp.cpp

@@ -5662,15 +5662,15 @@ static bool ocl_warpTransform_cols4(InputArray _src, OutputArray _dst, InputArra
     if ( !dev.isIntel() || !(type == CV_8UC1) ||
          !(dtype == CV_8UC1) || !(_dst.cols() % 4 == 0) ||
          !(borderType == cv::BORDER_CONSTANT &&
-          (interpolation == cv::INTER_NEAREST || interpolation == cv::INTER_LINEAR)))
+          (interpolation == cv::INTER_NEAREST || interpolation == cv::INTER_LINEAR || interpolation == cv::INTER_CUBIC)))
         return false;
 
     const char * const warp_op[2] = { "Affine", "Perspective" };
-    const char * const interpolationMap[3] = { "nearest", "linear", NULL };
+    const char * const interpolationMap[3] = { "nearest", "linear", "cubic" };
     ocl::ProgramSource program = ocl::imgproc::warp_transform_oclsrc;
     String kernelName = format("warp%s_%s_8u", warp_op[op_type], interpolationMap[interpolation]);
 
-    bool is32f = (interpolation == INTER_LINEAR);
+    bool is32f = (interpolation == INTER_CUBIC || interpolation == INTER_LINEAR) && op_type == OCL_OP_AFFINE;
     int wdepth = interpolation == INTER_NEAREST ? depth : std::max(is32f ? CV_32F : CV_32S, depth);
     int sctype = CV_MAKETYPE(wdepth, cn);
 

modules/imgproc/src/opencl/warp_transform.cl

@@ -117,6 +117,115 @@ __kernel void warpAffine_linear_8u(__global const uchar * src, int src_step, int
     vstore4(convert_uchar4_sat_rte(pixel), 0, dst + dst_index);
 }
 
+__constant float coeffs[128] =
+    { 0.000000f, 1.000000f, 0.000000f, 0.000000f, -0.021996f, 0.997841f, 0.024864f, -0.000710f, -0.041199f, 0.991516f, 0.052429f, -0.002747f,
+    -0.057747f, 0.981255f, 0.082466f, -0.005974f, -0.071777f, 0.967285f, 0.114746f, -0.010254f, -0.083427f, 0.949837f, 0.149040f, -0.015450f,
+    -0.092834f, 0.929138f, 0.185120f, -0.021423f, -0.100136f, 0.905418f, 0.222755f, -0.028038f, -0.105469f, 0.878906f, 0.261719f, -0.035156f,
+    -0.108971f, 0.849831f, 0.301781f, -0.042641f, -0.110779f, 0.818420f, 0.342712f, -0.050354f, -0.111031f, 0.784904f, 0.384285f, -0.058159f,
+    -0.109863f, 0.749512f, 0.426270f, -0.065918f, -0.107414f, 0.712471f, 0.468437f, -0.073494f, -0.103821f, 0.674011f, 0.510559f, -0.080750f,
+    -0.099220f, 0.634361f, 0.552406f, -0.087547f, -0.093750f, 0.593750f, 0.593750f, -0.093750f, -0.087547f, 0.552406f, 0.634361f, -0.099220f,
+    -0.080750f, 0.510559f, 0.674011f, -0.103821f, -0.073494f, 0.468437f, 0.712471f, -0.107414f, -0.065918f, 0.426270f, 0.749512f, -0.109863f,
+    -0.058159f, 0.384285f, 0.784904f, -0.111031f, -0.050354f, 0.342712f, 0.818420f, -0.110779f, -0.042641f, 0.301781f, 0.849831f, -0.108971f,
+    -0.035156f, 0.261719f, 0.878906f, -0.105469f, -0.028038f, 0.222755f, 0.905418f, -0.100136f, -0.021423f, 0.185120f, 0.929138f, -0.092834f,
+    -0.015450f, 0.149040f, 0.949837f, -0.083427f, -0.010254f, 0.114746f, 0.967285f, -0.071777f, -0.005974f, 0.082466f, 0.981255f, -0.057747f,
+    -0.002747f, 0.052429f, 0.991516f, -0.041199f, -0.000710f, 0.024864f, 0.997841f, -0.021996f };
+
+uchar4 read_pixels_cubic(__global const uchar * src, int tx, int ty,
+                         int src_offset, int src_step, int src_cols, int src_rows, uchar scalar)
+{
+    uchar4 pix;
+
+    if (tx >= 0 && (tx + 3) < src_cols && ty >= 0 && ty < src_rows)
+    {
+        pix = vload4(0, src + src_offset + ty * src_step + tx);
+    }
+    else
+    {
+        pix.s0 = GET_VAL((tx + 0), ty);
+        pix.s1 = GET_VAL((tx + 1), ty);
+        pix.s2 = GET_VAL((tx + 2), ty);
+        pix.s3 = GET_VAL((tx + 3), ty);
+    }
+
+    return pix;
+}
+
+__kernel void warpAffine_cubic_8u(__global const uchar * src, int src_step, int src_offset, int src_rows, int src_cols,
+                                  __global uchar * dst, int dst_step, int dst_offset, int dst_rows, int dst_cols,
+                                  __constant float * M, ST scalar_)
+{
+    int x = get_global_id(0) * 4;
+    int y = get_global_id(1);
+    uchar scalar = convert_uchar_sat_rte(scalar_);
+
+    if (x >= dst_cols || y >= dst_rows) return;
+
+    /* { M0, M1, M2 }
+     * { M3, M4, M5 }
+     */
+
+    float4 nx, ny;
+    nx = M[0] * convert_float4((vec_offset + (short4)x)) + M[1] * convert_float4((short4)y) + M[2];
+    ny = M[3] * convert_float4((vec_offset + (short4)x)) + M[4] * convert_float4((short4)y) + M[5];
+
+    int4 ax, ay;
+    ax = convert_int4_sat_rte((nx - floor(nx)) * 32.0f) & 31;
+    ay = convert_int4_sat_rte((ny - floor(ny)) * 32.0f) & 31;
+
+    int4 tx, ty;
+    int4 delta_x, delta_y;
+
+    delta_x = select((int4)1, (int4)0, ((nx - floor(nx))) * 64 > 63);
+    delta_y = select((int4)1, (int4)0, ((ny - floor(ny))) * 64 > 63);
+
+    tx = convert_int4_sat_rtn(nx) - delta_x;
+    ty = convert_int4_sat_rtn(ny) - delta_y;
+
+    __constant float * coeffs_x, * coeffs_y;
+    float4 sum = (float4)0.0f;
+    uchar4 pix;
+    float xsum;
+
+    coeffs_x = coeffs + (ax.s0 << 2);
+    coeffs_y = coeffs + (ay.s0 << 2);
+    for (int i = 0; i < 4; i++)
+    {
+        pix = read_pixels_cubic(src, tx.s0, ty.s0 + i, src_offset, src_step, src_cols, src_rows, scalar);
+        xsum = dot(convert_float4(pix), (float4)(coeffs_x[0], coeffs_x[1], coeffs_x[2], coeffs_x[3]));
+        sum.s0 = fma(xsum, coeffs_y[i], sum.s0);
+    }
+
+    coeffs_x = coeffs + (ax.s1 << 2);
+    coeffs_y = coeffs + (ay.s1 << 2);
+    for (int i = 0; i < 4; i++)
+    {
+        pix = read_pixels_cubic(src, tx.s1, ty.s1 + i, src_offset, src_step, src_cols, src_rows, scalar);
+        xsum = dot(convert_float4(pix), (float4)(coeffs_x[0], coeffs_x[1], coeffs_x[2], coeffs_x[3]));
+        sum.s1 = fma(xsum, coeffs_y[i], sum.s1);
+    }
+
+    coeffs_x = coeffs + (ax.s2 << 2);
+    coeffs_y = coeffs + (ay.s2 << 2);
+    for (int i = 0; i < 4; i++)
+    {
+        pix = read_pixels_cubic(src, tx.s2, ty.s2 + i, src_offset, src_step, src_cols, src_rows, scalar);
+        xsum = dot(convert_float4(pix), (float4)(coeffs_x[0], coeffs_x[1], coeffs_x[2], coeffs_x[3]));
+        sum.s2 = fma(xsum, coeffs_y[i], sum.s2);
+    }
+
+    coeffs_x = coeffs + (ax.s3 << 2);
+    coeffs_y = coeffs + (ay.s3 << 2);
+    for (int i = 0; i < 4; i++)
+    {
+        pix = read_pixels_cubic(src, tx.s3, ty.s3 + i, src_offset, src_step, src_cols, src_rows, scalar);
+        xsum = dot(convert_float4(pix), (float4)(coeffs_x[0], coeffs_x[1], coeffs_x[2], coeffs_x[3]));
+        sum.s3 = fma(xsum, coeffs_y[i], sum.s3);
+    }
+
+    int dst_index = x + y * dst_step + dst_offset;
+    vstore4(convert_uchar4_sat_rte(sum), 0, dst + dst_index);
+}
+
 __kernel void warpPerspective_nearest_8u(__global const uchar * src, int src_step, int src_offset, int src_rows, int src_cols,
                                          __global uchar * dst, int dst_step, int dst_offset, int dst_rows, int dst_cols,
                                          __constant float * M, ST scalar_)
@@ -212,3 +321,88 @@ __kernel void warpPerspective_linear_8u(__global const uchar * src, int src_step
     int dst_index = x + y * dst_step + dst_offset;
     vstore4(convert_uchar4_sat_rte(pixel), 0,  dst + dst_index);
 }
+
+__kernel void warpPerspective_cubic_8u(__global const uchar * src, int src_step, int src_offset, int src_rows, int src_cols,
+                                       __global uchar * dst, int dst_step, int dst_offset, int dst_rows, int dst_cols,
+                                       __constant float * M, ST scalar_)
+{
+    int x = get_global_id(0) * 4;
+    int y = get_global_id(1);
+    uchar scalar = convert_uchar_sat_rte(scalar_);
+
+    if (x >= dst_cols || y >= dst_rows) return;
+
+    /* { M0, M1, M2 }
+     * { M3, M4, M5 }
+     * { M6, M7, M8 }
+     */
+
+    float4 nx, ny, nz;
+    nx = M[0] * convert_float4(vec_offset + (short4)(x)) + M[1] * convert_float4((short4)y) + M[2];
+
+    ny = M[3] * convert_float4(vec_offset + (short4)(x)) + M[4] * convert_float4((short4)y) + M[5];
+
+    nz = M[6] * convert_float4(vec_offset + (short4)(x)) + M[7] * convert_float4((short4)y) + M[8];
+
+    float4 fz = select((float4)(0.0f), (float4)(1.0f / nz), nz != 0.0f);
+
+    nx = nx * fz;
+    ny = ny * fz;
+
+    int4 ax, ay;
+    ax = convert_int4_sat_rte((nx - floor(nx)) * 32.0f) & 31;
+    ay = convert_int4_sat_rte((ny - floor(ny)) * 32.0f) & 31;
+
+    int4 tx, ty;
+    int4 delta_x, delta_y;
+
+    delta_x = select((int4)1, (int4)0, ((nx - floor(nx))) * 64 > 63);
+    delta_y = select((int4)1, (int4)0, ((ny - floor(ny))) * 64 > 63);
+
+    tx = convert_int4_sat_rtn(nx) - delta_x;
+    ty = convert_int4_sat_rtn(ny) - delta_y;
+
+    __constant float * coeffs_x, * coeffs_y;
+    float4 sum = (float4)0.0f;
+    uchar4 pix;
+    float xsum;
+
+    coeffs_x = coeffs + (ax.s0 << 2);
+    coeffs_y = coeffs + (ay.s0 << 2);
+    for (int i = 0; i < 4; i++)
+    {
+        pix = read_pixels_cubic(src, tx.s0, ty.s0 + i, src_offset, src_step, src_cols, src_rows, scalar);
+        xsum = dot(convert_float4(pix), (float4)(coeffs_x[0], coeffs_x[1], coeffs_x[2], coeffs_x[3]));
+        sum.s0 = fma(xsum, coeffs_y[i], sum.s0);
+    }
+
+    coeffs_x = coeffs + (ax.s1 << 2);
+    coeffs_y = coeffs + (ay.s1 << 2);
+    for (int i = 0; i < 4; i++)
+    {
+        pix = read_pixels_cubic(src, tx.s1, ty.s1 + i, src_offset, src_step, src_cols, src_rows, scalar);
+        xsum = dot(convert_float4(pix), (float4)(coeffs_x[0], coeffs_x[1], coeffs_x[2], coeffs_x[3]));
+        sum.s1 = fma(xsum, coeffs_y[i], sum.s1);
+    }
+
+    coeffs_x = coeffs + (ax.s2 << 2);
+    coeffs_y = coeffs + (ay.s2 << 2);
+    for (int i = 0; i < 4; i++)
+    {
+        pix = read_pixels_cubic(src, tx.s2, ty.s2 + i, src_offset, src_step, src_cols, src_rows, scalar);
+        xsum = dot(convert_float4(pix), (float4)(coeffs_x[0], coeffs_x[1], coeffs_x[2], coeffs_x[3]));
+        sum.s2 = fma(xsum, coeffs_y[i], sum.s2);
+    }
+
+    coeffs_x = coeffs + (ax.s3 << 2);
+    coeffs_y = coeffs + (ay.s3 << 2);
+    for (int i = 0; i < 4; i++)
+    {
+        pix = read_pixels_cubic(src, tx.s3, ty.s3 + i, src_offset, src_step, src_cols, src_rows, scalar);
+        xsum = dot(convert_float4(pix), (float4)(coeffs_x[0], coeffs_x[1], coeffs_x[2], coeffs_x[3]));
+        sum.s3 = fma(xsum, coeffs_y[i], sum.s3);
+    }
+
+    int dst_index = x + y * dst_step + dst_offset;
+    vstore4(convert_uchar4_sat_rte(sum), 0, dst + dst_index);
+}

modules/imgproc/test/ocl/test_warp.cpp

@@ -437,7 +437,7 @@ OCL_INSTANTIATE_TEST_CASE_P(ImgprocWarp, WarpAffine, Combine(
 
 OCL_INSTANTIATE_TEST_CASE_P(ImgprocWarp, WarpAffine_cols4, Combine(
                             Values((MatType)CV_8UC1),
-                            Values((Interpolation)INTER_NEAREST, (Interpolation)INTER_LINEAR),
+                            Values((Interpolation)INTER_NEAREST, (Interpolation)INTER_LINEAR, (Interpolation)INTER_CUBIC),
                             Bool(),
                             Bool()));
 
@@ -449,7 +449,7 @@ OCL_INSTANTIATE_TEST_CASE_P(ImgprocWarp, WarpPerspective, Combine(
 
 OCL_INSTANTIATE_TEST_CASE_P(ImgprocWarp, WarpPerspective_cols4, Combine(
                             Values((MatType)CV_8UC1),
-                            Values((Interpolation)INTER_NEAREST, (Interpolation)INTER_LINEAR),
+                            Values((Interpolation)INTER_NEAREST, (Interpolation)INTER_LINEAR, (Interpolation)INTER_CUBIC),
                             Bool(),
                             Bool()));