使用 ARM NEON 内在函数对 cvtColor 进行 SIMD 优化 [英] SIMD optimization of cvtColor using ARM NEON intrinsics
本文介绍了使用 ARM NEON 内在函数对 cvtColor 进行 SIMD 优化的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我正在研究 BGR 到灰度转换的 SIMD 优化，这相当于 ):
void cvtBGR2GraySSEShort(Mat& src, Mat& dest){const int size = src.size().area()*src.channels();uchar* s = src.ptr(0);uchar* d = dest.ptr<uchar>(0);//数据结构//BGR BGR BGR BGR BGR B//GR BGR BGR BGR BGR BG//R BGR BGR BGR BGR BGR//洗牌到BBBBBBGGGGGRRRRRconst __m128i mask1 = _mm_setr_epi8(0,3,6,9,12,15,1,4,7,10,13,2,5,8,11,14);const __m128i smask1 = _mm_setr_epi8(6,7,8,9,10,0,1,2,3,4,5,11,12,13,14,15);const __m128i ssmask1 = _mm_setr_epi8(11,12,13,14,15,0,1,2,3,4,5,6,7,8,9,10);//洗牌到GGGGGGBBBBBRRRRRconst __m128i mask2 = _mm_setr_epi8(0,3,6,9,12,15, 2,5,8,11,14,1,4,7,10,13);//const __m128i smask2 = _mm_setr_epi8(6,7,8,9,10,0,1,2,3,4,5,11,12,13,14,15);与smask1相同const __m128i ssmask2 = _mm_setr_epi8(0,1,2,3,4,11,12,13,14,15,5,6,7,8,9,10);//洗牌到RRRRRRGGGGGBBBBB//__m128i mask3 = _mm_setr_epi8(0,3,6,9,12,15, 2,5,8,11,14,1,4,7,10,13);//同mask2//const __m128i smask3 = _mm_setr_epi8(6,7,8,9,10,0,1,2,3,4,5,6,7,8,9,10);//同smask1//const __m128i ssmask3 = _mm_setr_epi8(11,12,13,14,15,0,1,2,3,4,5,6,7,8,9,10);//同ssmask1//混合蒙版const __m128i bmask1 = _mm_setr_epi8(255,255,255,255,255,255,0,0,0,0,0,0,0,0,0,0)；const __m128i bmask2 = _mm_setr_epi8(255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0)；const __m128i bmask3 = _mm_setr_epi8(255,255,255,255,255,0,0,0,0,0,0,0,0,0,0,0)；const __m128i bmask4 = _mm_setr_epi8(255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0)；const int shift = 8;const int amp = 1< 解决方案
好的，下面是我刚写的那个函数的完全优化版本(请注意，如果大小小于 32，这个函数只会返回.)
/** 创建于:2014. 7. 27.* 作者:李杰* Project FANIC - 最快的 ARM NEON 实施挑战*///void fanicCvtBGR2GrayNEON(void *pDst, void *pSrc, unsigned int size);//Y = 0.114*B + 0.587*G + 0.299*R.文本.手臂.global fanicCvtBGR2GrayNEONpDst .req r0pSrc .req r1大小 .req r2.align 5.funcfanicCvtBGR2GrayNEON:pld [pSrc]潜艇尺寸，尺寸，#32pld [pSrc，#64]微信pld [pSrc，#64*2]vmov.i8 d0，#29vmov.i8 d1，#150vmov.i8 d2，#77.align 51:vld3.8 {d20，d21，d22}，[pSrc]！vld3.8 {d23, d24, d25}, [pSrc]！vld3.8 {d26, d27, d28}，[pSrc]！vld3.8 {d29，d30，d31}，[pSrc]！vmull.u8 q8, d20, d0vmal.u8 q8, d21, d1vmal.u8 q8, d22, d2vmull.u8 q9, d23, d0vmal.u8 q9, d24, d1vmal.u8 q9, d25, d2vmull.u8 q10, d26, d0vmal.u8 q10, d27, d1vmal.u8 q10, d28, d2vmull.u8 q11, d29, d0vmal.u8 q11, d30, d1vmal.u8 q11、d31、d2vrshrn.u16 d24, q8, #8vrshrn.u16 d25，q9，#8vrshrn.u16 d26，q10，#8vrshrn.u16 d27，q11，#8潜艇尺寸，尺寸，#32pld [pSrc，#64*3]pld [pSrc，#64*4]vst1.8 {q12, q13}, [pDst]！bpl 1bcmp 大小，#-32添加 pSrc、pSrc、大小bxle lr添加 pSrc、pSrc、大小、lsl #1添加 pDst、pDst、大小乙 1乙.endfunc.结尾如您所见，尽管展开繁重，但在汇编中编写 NEON 代码比在内部函数中编写更容易、更短.
玩得开心.
I'm working on a SIMD optimization of BGR to grayscale conversion which is equivalent to OpenCV's cvtColor() function. There is an Intel SSE version of this function and I'm referring to it. (What I'm doing is basically converting SSE code to NEON code.)
I've almost finished writing the code, and can compile it with g++, but I can't get the proper output. Does anyone have any ideas what the error could be?
What I'm getting (incorrect):
What I should be getting:
Here's my code:
#include <opencv/cv.hpp>
#include <opencv/highgui.h>
#include <arm_neon.h>
//#include <iostream>
using namespace std;
//using namespace cv;
#define int8x16_to_8x8x2(v) ((int8x8x2_t) { vget_low_s8(v), vget_high_s8(v) })
void cvtBGR2GrayNEON(cv::Mat& src, cv::Mat& dest)
{
const int size = src.size().area()*src.channels();
uchar* s = src.ptr<uchar>(0);
uchar* d = dest.ptr<uchar>(0);
const int8x16_t mask1 = {0,3,6,9,12,15,1,4,7,10,13,2,5,8,11,14};
const int8x16_t smask1 = {6,7,8,9,10,0,1,2,3,4,5,11,12,13,14,15};
const int8x16_t ssmask1 = {11,12,13,14,15,0,1,2,3,4,5,6,7,8,9,10};
const int8x16_t mask2 = {0,3,6,9,12,15, 2,5,8,11,14,1,4,7,10,13};
const int8x16_t ssmask2 = {0,1,2,3,4,11,12,13,14,15,5,6,7,8,9,10};
const int8x16_t bmask1 = {255,255,255,255,255,255,0,0,0,0,0,0,0,0,0,0};
const int8x16_t bmask2 = {255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0};
const int8x16_t bmask3 = {255,255,255,255,255,0,0,0,0,0,0,0,0,0,0,0};
const int8x16_t bmask4 = {255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0};
const int shift = 8;
const int amp = 1<<shift;
const int16_t _R_ = (int16_t)(amp*0.299);
const int16_t _G_ = (int16_t)(amp*0.587);
const int16_t _B_ = (int16_t)(amp*0.114);
const int16x8_t R = vdupq_n_s16(_R_);
const int16x8_t G = vdupq_n_s16(_G_);
const int16x8_t B = vdupq_n_s16(_B_);
const int8x16_t zero = vdupq_n_s8(0);
for(int i = 0; i < size; i += 48)
{
int8x16_t a = vld1q_s8((int8_t *) s + i);
int8x16_t b = vld1q_s8((int8_t *) s + i + 16);
int8x16_t c = vld1q_s8((int8_t *) s + i + 32);
a = vcombine_s8(vtbl2_s8(int8x16_to_8x8x2(a),vget_low_s8(mask1)),vtbl2_s8(int8x16_to_8x8x2(a),vget_high_s8(mask1)));
b = vcombine_s8(vtbl2_s8(int8x16_to_8x8x2(b), vget_low_s8(mask2)), vtbl2_s8(int8x16_to_8x8x2(b), vget_high_s8(mask2)));
c = vcombine_s8(vtbl2_s8(int8x16_to_8x8x2(c), vget_low_s8(mask2)), vtbl2_s8(int8x16_to_8x8x2(c), vget_high_s8(mask2)));
//BBBBBB
const int8x16_t aaaa = vbslq_s8(c, vbslq_s8(b, a, bmask1), bmask2);
a = vcombine_s8(vtbl2_s8(int8x16_to_8x8x2(a), vget_low_s8(smask1)), vtbl2_s8(int8x16_to_8x8x2(a), vget_high_s8(smask1)));
b = vcombine_s8(vtbl2_s8(int8x16_to_8x8x2(b), vget_low_s8(smask1)), vtbl2_s8(int8x16_to_8x8x2(b), vget_high_s8(smask1)));
c = vcombine_s8(vtbl2_s8(int8x16_to_8x8x2(c), vget_low_s8(smask1)), vtbl2_s8(int8x16_to_8x8x2(c), vget_high_s8(smask1)));
//GGGGGG
const int8x16_t bbbb = vbslq_s8(c, vbslq_s8(b, a, bmask3), bmask2);
a = vcombine_s8(vtbl2_s8(int8x16_to_8x8x2(a), vget_low_s8(ssmask1)), vtbl2_s8(int8x16_to_8x8x2(a), vget_high_s8(ssmask1)));
c = vcombine_s8(vtbl2_s8(int8x16_to_8x8x2(c), vget_low_s8(ssmask1)), vtbl2_s8(int8x16_to_8x8x2(c), vget_high_s8(ssmask1)));
b = vcombine_s8(vtbl2_s8(int8x16_to_8x8x2(b), vget_low_s8(ssmask2)), vtbl2_s8(int8x16_to_8x8x2(b), vget_high_s8(ssmask2)));
//RRRRRR
const int8x16_t cccc = vbslq_s8(c, vbslq_s8(b, a, bmask3), bmask4);
/*
int8x8x2_t a1 = vzip_s8(vget_high_s8(aaaa), vget_high_s8(zero));
int8x8x2_t a2 = vzip_s8(vget_low_s8(aaaa), vget_low_s8(zero));
*/
int8x16_t a1 = aaaa;
int8x16_t a2 = zero;
int8x16x2_t temp1 = vzipq_s8(a1, a2);
a1 = temp1.val[0];
a2 = temp1.val[1];
int16x8_t aa1 = vmulq_s16((int16x8_t)a2, B);
int16x8_t aa2 = vmulq_s16((int16x8_t)a1, B);
int8x16_t b1 = bbbb;
int8x16_t b2 = zero;
int8x16x2_t temp2 = vzipq_s8(b1, b2);
b1 = temp2.val[0];
b2 = temp2.val[1];
int16x8_t bb1 = vmulq_s16((int16x8_t)b2, G);
int16x8_t bb2 = vmulq_s16((int16x8_t)b1, G);
int8x16_t c1 = cccc;
int8x16_t c2 = zero;
int8x16x2_t temp3 = vzipq_s8(c1, c2);
c1 = temp3.val[0];
c2 = temp3.val[1];
int16x8_t cc1 = vmulq_s16((int16x8_t)c2, R);
int16x8_t cc2 = vmulq_s16((int16x8_t)c1, R);
aa1 = vaddq_s16(aa1, bb1);
aa1 = vaddq_s16(aa1, cc1);
aa2 = vaddq_s16(aa2, bb2);
aa2 = vaddq_s16(aa2, cc2);
const int shift1 = 8;
aa1 = vshrq_n_s16(aa1, shift1);
aa2 = vshrq_n_s16(aa2, shift1);
uint8x8_t aaa1 = vqmovun_s16(aa1);
uint8x8_t aaa2 = vqmovun_s16(aa2);
uint8x16_t result = vcombine_u8(aaa1, aaa2);
vst1q_u8((uint8_t *)(d), result);
d+=16;
}
}
int main()
{
cv::Mat src = cv::imread("Lenna.bmp");
cv::Mat dest(src.rows, src.cols, CV_8UC1);
cvtBGR2GrayNEON(src, dest);
cv::imwrite("grey.jpg", dest);
return 0;
}
Here is equivalent SSE code (from here):
void cvtBGR2GraySSEShort(Mat& src, Mat& dest)
{
const int size = src.size().area()*src.channels();
uchar* s = src.ptr<uchar>(0);
uchar* d = dest.ptr<uchar>(0);
//data structure
//BGR BGR BGR BGR BGR B
//GR BGR BGR BGR BGR BG
//R BGR BGR BGR BGR BGR
//shuffle to BBBBBBGGGGGRRRRR
const __m128i mask1 = _mm_setr_epi8(0,3,6,9,12,15,1,4,7,10,13,2,5,8,11,14);
const __m128i smask1 = _mm_setr_epi8(6,7,8,9,10,0,1,2,3,4,5,11,12,13,14,15);
const __m128i ssmask1 = _mm_setr_epi8(11,12,13,14,15,0,1,2,3,4,5,6,7,8,9,10);
//shuffle to GGGGGGBBBBBRRRRR
const __m128i mask2 = _mm_setr_epi8(0,3,6,9,12,15, 2,5,8,11,14,1,4,7,10,13);
//const __m128i smask2 = _mm_setr_epi8(6,7,8,9,10,0,1,2,3,4,5,11,12,13,14,15);same as smask1
const __m128i ssmask2 = _mm_setr_epi8(0,1,2,3,4,11,12,13,14,15,5,6,7,8,9,10);
//shuffle to RRRRRRGGGGGBBBBB
//__m128i mask3 = _mm_setr_epi8(0,3,6,9,12,15, 2,5,8,11,14,1,4,7,10,13);//same as mask2
//const __m128i smask3 = _mm_setr_epi8(6,7,8,9,10,0,1,2,3,4,5,6,7,8,9,10);//same as smask1
//const __m128i ssmask3 = _mm_setr_epi8(11,12,13,14,15,0,1,2,3,4,5,6,7,8,9,10);//same as ssmask1
//blend mask
const __m128i bmask1 = _mm_setr_epi8
(255,255,255,255,255,255,0,0,0,0,0,0,0,0,0,0);
const __m128i bmask2 = _mm_setr_epi8
(255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0);
const __m128i bmask3 = _mm_setr_epi8
(255,255,255,255,255,0,0,0,0,0,0,0,0,0,0,0);
const __m128i bmask4 = _mm_setr_epi8
(255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0);
const int shift = 8;
const int amp = 1<<shift;
const int _R_=(int)(amp*0.299);
const int _G_=(int)(amp*0.587);
const int _B_=(int)(amp*0.114);
const __m128i R = _mm_set1_epi16(_R_);
const __m128i G = _mm_set1_epi16(_G_);
const __m128i B = _mm_set1_epi16(_B_);
const __m128i zero = _mm_setzero_si128();
for(int i=0;i<size;i+=48)
{
__m128i a = _mm_shuffle_epi8(_mm_load_si128((__m128i*)(s+i)),mask1);
__m128i b = _mm_shuffle_epi8(_mm_load_si128((__m128i*)(s+i+16)),mask2);
__m128i c = _mm_shuffle_epi8(_mm_load_si128((__m128i*)(s+i+32)),mask2);
const __m128i aaaa = _mm_blendv_epi8(c,_mm_blendv_epi8(b,a,bmask1),bmask2);
a = _mm_shuffle_epi8(a,smask1);
b = _mm_shuffle_epi8(b,smask1);
c = _mm_shuffle_epi8(c,smask1);
const __m128i bbbb =_mm_blendv_epi8(c,_mm_blendv_epi8(b,a,bmask3),bmask2);
a = _mm_shuffle_epi8(a,ssmask1);
c = _mm_shuffle_epi8(c,ssmask1);
b = _mm_shuffle_epi8(b,ssmask2);
const __m128i cccc =_mm_blendv_epi8(c,_mm_blendv_epi8(b,a,bmask3),bmask4);
__m128i a1 = _mm_unpackhi_epi8(aaaa,zero);
__m128i a2 = _mm_unpacklo_epi8(aaaa,zero);
a1 = _mm_mullo_epi16(a1,B);
a2 = _mm_mullo_epi16(a2,B);
__m128i b1 = _mm_unpackhi_epi8(bbbb,zero);
__m128i b2 = _mm_unpacklo_epi8(bbbb,zero);
b1 = _mm_mullo_epi16(b1,G);
b2 = _mm_mullo_epi16(b2,G);
__m128i c1 = _mm_unpackhi_epi8(cccc,zero);
__m128i c2 = _mm_unpacklo_epi8(cccc,zero);
c1 = _mm_mullo_epi16(c1,R);
c2 = _mm_mullo_epi16(c2,R);
a1 = _mm_add_epi16(a1,b1);
a1 = _mm_add_epi16(a1,c1);
a2 = _mm_add_epi16(a2,b2);
a2 = _mm_add_epi16(a2,c2);
a1 = _mm_srli_epi16(a1,8);
a2 = _mm_srli_epi16(a2,8);
a = _mm_packus_epi16(a1,a2);
_mm_stream_si128((__m128i*)(d),a);
d+=16;
}
}
解决方案
Ok, below is a FULLY OPTIMIZED version of that function I just wrote (Beware that this function simply returns if size is smaller than 32.)
/*
* Created on: 2014. 7. 27.
* Author: Jake Lee
* Project FANIC - Fastest ARM NEON Implementaion Challenge
*/
// void fanicCvtBGR2GrayNEON(void *pDst, void *pSrc, unsigned int size);
// Y = 0.114*B + 0.587*G + 0.299*R
.text
.arm
.global fanicCvtBGR2GrayNEON
pDst .req r0
pSrc .req r1
size .req r2
.align 5
.func
fanicCvtBGR2GrayNEON:
pld [pSrc]
subs size, size, #32
pld [pSrc, #64]
bxmi lr
pld [pSrc, #64*2]
vmov.i8 d0, #29
vmov.i8 d1, #150
vmov.i8 d2, #77
.align 5
1:
vld3.8 {d20, d21, d22}, [pSrc]!
vld3.8 {d23, d24, d25}, [pSrc]!
vld3.8 {d26, d27, d28}, [pSrc]!
vld3.8 {d29, d30, d31}, [pSrc]!
vmull.u8 q8, d20, d0
vmlal.u8 q8, d21, d1
vmlal.u8 q8, d22, d2
vmull.u8 q9, d23, d0
vmlal.u8 q9, d24, d1
vmlal.u8 q9, d25, d2
vmull.u8 q10, d26, d0
vmlal.u8 q10, d27, d1
vmlal.u8 q10, d28, d2
vmull.u8 q11, d29, d0
vmlal.u8 q11, d30, d1
vmlal.u8 q11, d31, d2
vrshrn.u16 d24, q8, #8
vrshrn.u16 d25, q9, #8
vrshrn.u16 d26, q10, #8
vrshrn.u16 d27, q11, #8
subs size, size, #32
pld [pSrc, #64*3]
pld [pSrc, #64*4]
vst1.8 {q12, q13}, [pDst]!
bpl 1b
cmp size, #-32
add pSrc, pSrc, size
bxle lr
add pSrc, pSrc, size, lsl #1
add pDst, pDst, size
b 1b
.endfunc
.end
As you can see, it's so much easier and shorter writing NEON codes in assembly than in intrinsics despite the heavy unrolling.
Have fun.
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