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Computer Vision

This paper by Kim Nam Woo from Dongseo University presents a comprehensive overview of color models in digital image processing. It includes detailed algorithms for conversions among the RGB, HSI, and YCbCr color formats. The RGB-to-YCbCr conversion is explained with specific formulas, and the HSI model is elaborated through code for color extraction and manipulation. Additionally, the paper discusses skin color detection using the Hsu-Mottaleb-Jain approach, emphasizing practical applications in computer vision.

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Computer Vision

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  1. Computer Vision Kim Nam Woo

  2. RGB Color Model G R B Digital Image Processing, Kim Nam Woo, Dongseo Univ.

  3. YMC Color Model 2014-09-19 Digital Image Processing, Kim Nam Woo, Dongseo Univ. 3

  4. HSI Color Model 2014-09-19 Digital Image Processing, Kim Nam Woo, Dongseo Univ. 4

  5. RGB →YCbCr void RGBtoYCbCr(BYTE R, BYTE G, BYTE B, float *pfY, float *pfCb, float *pfCr) { *pfY = (77.*R + 150.*G + 29.*B)/256.; *pfCb = (-44.*R - 87.*G + 131.*B)/256. + 128; *pfCr = (131.*R - 110.*G - 21.*B)/256. + 128; } 2014-09-19 Digital Image Processing, Kim Nam Woo, Dongseo Univ. 5

  6. RGB →HSI void RGBtoHSI(int H, int S, int I){    int min;    unsigned char r,g,b;    float H,S,I;    float angle;    if(r==0 && g==0 && b==0)        H=0;S=0;I=0;    if((r<=g) && (r<=b))         min=r;    else if((g<=r) && (g<=b))        min=g;    else         min=b; if((r==g) && (g==b))    {        H=0.0f;        S=0.0f;    } else    {        if(b>g)        {            H=360.0f-H;        }        else        {            H=(float)acos(angle);            H *=57.29577951f;        }        S=(1.0f-(3.0f/(r+b+g)) * min);        angle = (r-0.5f*g-0.5f*b)                /(float)sqrt((r-g)*(r-g)+(r-b)*(g-b));    }    I=(r+g+b)/3.0;} Digital Image Processing, Kim Nam Woo, Dongseo Univ.

  7. Skin Color BOOL HsuMottalebJain_Ellipse2002(BYTE R, BYTE G, BYTE B) { float Y, Cb, Cr, x, y; const float Cx=109.38, Cy=152.02, theta=2.53, ECx=1.6, ECy=2.41, a=25.39, b=14.03; RGBtoYCbCr(R, G, B, &Y, &Cb, &Cr); x=((cos(theta))*(Cb-Cx)) + ((sin(theta))*(Cr-Cy)); y=((-sin(theta))*(Cb-Cx)) + ((cos(theta))*(Cr-Cy)); if((((x-ECx)*(x-ECx))/(a*a)) + (((y-ECy)*(y-ECy))/(b*b)) <= 1) return true; else return false; } Digital Image Processing, Kim Nam Woo, Dongseo Univ.

  8. Skin Color BOOL HsuMottalebJain_Central2002(BYTE R, BYTE G, BYTE B) { float Y, Cb, Cr, wCb, wCr, BCb, BCr; const float Cx=109.38, Cy=152.02, theta=2.53, ECx=1.6, ECy=2.41, a=25.39, b=14.03; RGBtoYCbCr(R, G, B, &Y, &Cb, &Cr); HsuMottalebJain_CentralEg2002(Y, &wCb, &wCr, &BCb, &BCr); if((Cb < BCb+0.35*wCb && Cb > BCb-0.35*wCb) && (Cr > BCr-0.35*wCr && Cr < BCr+0.35*wCr)) return true; else return false; } 2014-09-19 Digital Image Processing, Kim Nam Woo, Dongseo Univ. 8

  9. Skin Color void HsuMottalebJain_CentralEg2002(float Y, float *wCb, float *wCr, float *BCb, float *BCr) { const float Kl=125., Kh=188., Ymin=16., Ymax=235., cWCb=46.97, cWLCb=23. ; if(Y<125.) { *wCb = 23.+(23.97*Y + 383.52)/109.; *wCr = 20.+(18.76*Y + 2.76)/109.; *BCb = 108.+(1250.-10*Y)/109.; *BCr = 154.-(1250.-10*Y)/109.; } else if(Y>188.) { *wCb = 14.+(-32.97*Y + 7747.95)/47.; *wCr = 10.+(-28.76*Y + 675.86)/47.; *BCb = 108.+(10*Y-1880.)/47.; *BCr = 154.+(22*Y-4136.)/109.; } else { *wCb = 46.97; *wCr = 38.76; *BCb = 108.; *BCr = 108.; } } 2014-09-19 Digital Image Processing, Kim Nam Woo, Dongseo Univ. 9

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