From c173d9fa183cc8c5687d84683ab5189cc22f580f Mon Sep 17 00:00:00 2001
From: Ilya Lavrenov <ilya.lavrenov@itseez.com>
Date: Tue, 7 Oct 2014 15:33:09 +0000
Subject: [PATCH] cv::cvtColor (RGB2HLS CV_8U)

---
 modules/imgproc/src/color.cpp | 66 +++++++++++++++++++++++++++++++++--
 1 file changed, 63 insertions(+), 3 deletions(-)

diff --git a/modules/imgproc/src/color.cpp b/modules/imgproc/src/color.cpp
index 6b2f9ffc05..975617fff6 100644
--- a/modules/imgproc/src/color.cpp
+++ b/modules/imgproc/src/color.cpp
@@ -3208,7 +3208,14 @@ struct RGB2HLS_b
     typedef uchar channel_type;
 
     RGB2HLS_b(int _srccn, int _blueIdx, int _hrange)
-    : srccn(_srccn), cvt(3, _blueIdx, (float)_hrange) {}
+    : srccn(_srccn), cvt(3, _blueIdx, (float)_hrange)
+    {
+        #if CV_NEON
+        v_scale_inv = vdupq_n_f32(1.f/255.f);
+        v_scale = vdupq_n_f32(255.f);
+        v_alpha = vdup_n_u8(ColorChannel<uchar>::max());
+        #endif
+    }
 
     void operator()(const uchar* src, uchar* dst, int n) const
     {
@@ -3218,8 +3225,41 @@ struct RGB2HLS_b
         for( i = 0; i < n; i += BLOCK_SIZE, dst += BLOCK_SIZE*3 )
         {
             int dn = std::min(n - i, (int)BLOCK_SIZE);
+            j = 0;
 
-            for( j = 0; j < dn*3; j += 3, src += scn )
+            #if CV_NEON
+            for ( ; j <= (dn - 8) * 3; j += 24, src += 8 * scn)
+            {
+                uint16x8_t v_t0, v_t1, v_t2;
+
+                if (scn == 3)
+                {
+                    uint8x8x3_t v_src = vld3_u8(src);
+                    v_t0 = vmovl_u8(v_src.val[0]);
+                    v_t1 = vmovl_u8(v_src.val[1]);
+                    v_t2 = vmovl_u8(v_src.val[2]);
+                }
+                else
+                {
+                    uint8x8x4_t v_src = vld4_u8(src);
+                    v_t0 = vmovl_u8(v_src.val[0]);
+                    v_t1 = vmovl_u8(v_src.val[1]);
+                    v_t2 = vmovl_u8(v_src.val[2]);
+                }
+
+                float32x4x3_t v_dst;
+                v_dst.val[0] = vmulq_f32(vcvtq_f32_u32(vmovl_u16(vget_low_u16(v_t0))), v_scale_inv);
+                v_dst.val[1] = vmulq_f32(vcvtq_f32_u32(vmovl_u16(vget_low_u16(v_t1))), v_scale_inv);
+                v_dst.val[2] = vmulq_f32(vcvtq_f32_u32(vmovl_u16(vget_low_u16(v_t2))), v_scale_inv);
+                vst3q_f32(buf + j, v_dst);
+
+                v_dst.val[0] = vmulq_f32(vcvtq_f32_u32(vmovl_u16(vget_high_u16(v_t0))), v_scale_inv);
+                v_dst.val[1] = vmulq_f32(vcvtq_f32_u32(vmovl_u16(vget_high_u16(v_t1))), v_scale_inv);
+                v_dst.val[2] = vmulq_f32(vcvtq_f32_u32(vmovl_u16(vget_high_u16(v_t2))), v_scale_inv);
+                vst3q_f32(buf + j + 12, v_dst);
+            }
+            #endif
+            for( ; j < dn*3; j += 3, src += scn )
             {
                 buf[j] = src[0]*(1.f/255.f);
                 buf[j+1] = src[1]*(1.f/255.f);
@@ -3227,7 +3267,23 @@ struct RGB2HLS_b
             }
             cvt(buf, buf, dn);
 
-            for( j = 0; j < dn*3; j += 3 )
+            j = 0;
+            #if CV_NEON
+            for ( ; j <= (dn - 8) * 3; j += 24)
+            {
+                float32x4x3_t v_src0 = vld3q_f32(buf + j), v_src1 = vld3q_f32(buf + j + 12);
+
+                uint8x8x3_t v_dst;
+                v_dst.val[0] = vqmovn_u16(vcombine_u16(vqmovn_u32(cv_vrndq_u32_f32(v_src0.val[0])),
+                                                       vqmovn_u32(cv_vrndq_u32_f32(v_src1.val[0]))));
+                v_dst.val[1] = vqmovn_u16(vcombine_u16(vqmovn_u32(cv_vrndq_u32_f32(vmulq_f32(v_src0.val[1], v_scale))),
+                                                       vqmovn_u32(cv_vrndq_u32_f32(vmulq_f32(v_src1.val[1], v_scale)))));
+                v_dst.val[2] = vqmovn_u16(vcombine_u16(vqmovn_u32(cv_vrndq_u32_f32(vmulq_f32(v_src0.val[2], v_scale))),
+                                                       vqmovn_u32(cv_vrndq_u32_f32(vmulq_f32(v_src1.val[2], v_scale)))));
+                vst3_u8(dst + j, v_dst);
+            }
+            #endif
+            for( ; j < dn*3; j += 3 )
             {
                 dst[j] = saturate_cast<uchar>(buf[j]);
                 dst[j+1] = saturate_cast<uchar>(buf[j+1]*255.f);
@@ -3238,6 +3294,10 @@ struct RGB2HLS_b
 
     int srccn;
     RGB2HLS_f cvt;
+    #if CV_NEON
+    float32x4_t v_scale, v_scale_inv;
+    uint8x8_t v_alpha;
+    #endif
 };