RGB to YUV Conversion Example

Intel® oneAPI DPC++/C++ Compiler Developer Guide and Reference

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ID 767253

Date 3/22/2024

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RGB to YUV Conversion Example

This example converts a 2D image from the RGB format to the YUV format. It demonstrates how storing both images in 2D SoA n_containers can improve performance.

#include <iostream>
#include <sdlt/sdlt.h>
using namespace sdlt;
#define WIDTH 1024
#define HEIGHT 1024

struct RGBs {
    float r;
    float g;
    float b;
};

struct YUVs {
    float y;
    float u;
    float v;
    
    YUVs(){ };

    YUVs& operator=(const RGBs &tmp){
        y = 0.229f * tmp.r + 0.587f * tmp.g + 0.114f * tmp.b;
        u = -0.147f * tmp.r - 0.289f * tmp.g + 0.436f * tmp.b;
        v = 0.615 * tmp.r - 0.515f * tmp.g - 0.100 * tmp.b;
        return *this;
    }
    YUVs(const RGBs &tmp){
        y = 0.229f * tmp.r + 0.587f * tmp.g + 0.114f * tmp.b;
        u = -0.147f * tmp.r - 0.289f * tmp.g + 0.436f * tmp.b;
        v = 0.615 * tmp.r - 0.515f * tmp.g - 0.100 * tmp.b;
   }
};

SDLT_PRIMITIVE(RGBs, r, g, b)
SDLT_PRIMITIVE(YUVs, y, u, v)

int main(){
    typedef layout::soa<> LayoutT;
    n_extent_t<int, int> extents(HEIGHT, WIDTH);

    /*  Creating a typedef for SoA N-dimensional container.
        RGBTy and YUVTy are user defined structures whose collection needs to be stored in SoA format in memory.
        Layout in memory specified as layout::soa.
        In the below case N-dimensional SoA container is used in 2-D context
    */
    typedef sdlt::n_container< RGBs, LayoutT, decltype(extents) > ContainerRGB;
    typedef sdlt::n_container< YUVs, LayoutT, decltype(extents) > ContainerYUV;

    //Instantiate Input and Output Containers
    ContainerRGB inputRGB(extents);
    ContainerYUV outputYUV(extents);

    auto input = inputRGB.const_access();   //Get Constant Accessor object for inputRGB
    auto output = outputYUV.access();       //Get Accessor object for outputYUV

    //Select the iteration range in each dimension
    const auto iRGB1 = bounds_d<1>(input);  //bound_d<1>(input);
    const auto iRGB0 = bounds_d<0>(input);  //bound_d<0>(input);

    for(int y = iRGB0.lower(); y < iRGB0.upper(); y++)
    {
        #pragma simd
        for (int x = iRGB1.lower(); x < iRGB1.upper(); x++){
            const RGBs temp1 = input[y][x];
            YUVs temp2 = temp1;
            output[y][x] = temp2;
        }
    }
    return 0;
}

Parent topic: Examples

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Intel® oneAPI DPC++/C++ Compiler Developer Guide and Reference

RGB to YUV Conversion Example