Replace a color value of an image

ConstUnsignedCharRgbmax =255;#defineEqualzero (a) ((a) = = 0)voidCVTRGBTOHSI (cgfloat ir,cgfloat IG, cgfloat IB, unsignedChar* RH, unsignedChar* RS, unsignedChar*RI) {    /*When a person observes a colored object, it uses hue, saturation, brightness to describe the object's color. Hsi(hue-saturation-intensity (lightness), the HSI or Hsl) color model describes the color characteristics with H, S, I three parameters, where h defines the wavelength of the color, called the hue, and S indicates the degree of depth of the color, called saturation; I represents strength or brightness. In the HSI color model of the double hexagonal pyramid, I is the intensity axis, the angle range of the hue h is [0,2π], where the pure red angle is 0, the pure green angle is 2Π/3, the pure blue angle is 4Π/3*/    Const   floatPI2 =2*3.1415926; floatR = (float) IR; floatg = (float) IG; floatB = (float) IB; floatMaxval =Max (Max (R, G), b); floatMinval =min (min (R, G), b); floati = (r + G + B)/3; floats =0.0f; floath =0.0f; if(! Equalzero (i) &&! Equalzero (Maxval-minval)) {        floatdiff =0.5f* (R-g + Rb); floatDIFF2 = (r-g) * (r-g) + (r-g) * (g-b);//diff2 Forever > 0        floatSita = ACOs (Diff/sqrt (diff2))/pi2;//angle, PI2 is 1h = (g>=b)? Sita: (1.0f-Sita); S=1.0f-minval/i; }    if(H <0.0f) H + =1.0f; Else if(H >1.0f) H-=1.0f; *RH = (unsignedChar) round (H*rgbmax);//range:0 to 255;*rs = (unsignedChar) round (S*rgbmax);//range:0 to 255;*ri = (unsignedChar) round (I*rgbmax);//range:0 to 255;}unsignedCharSubunsignedchar (unsignedChara,unsignedCharb) {    return(a>b)? (a):(B-a);}-(BOOL) Besimilarcolor: (uicolor*) Color1 Withcolor: (uicolor*) Color2 withdifference: (unsignedChar) difference{cgfloat r1,r2,g1,g2,b1,b2,a1,a2; unsignedCharH1,h2,s1,s2,i1,i2; [Color1 getred:&AMP;R1 green:&g1 blue:&b1 alpha:&A1]; [Color2 getred:&AMP;R2 green:&g2 blue:&b2 alpha:&A2]; CVTRGBTOHSI (R1, G1, B1,&AMP;H1, &AMP;S1, &i1); CVTRGBTOHSI (R2, G2, B2,&AMP;H2, &AMP;S2, &i2); unsignedCharMaxgap =difference; if(A1 = = A2 && (Subunsignedchar (H1, H2) <= maxgap) && (Subunsignedchar (S1, S2) <= maxgap) && ( Subunsignedchar (I1, I2) <=maxgap)) {        returnYES; }    returnNO;}#pragmaMark Picture Replacement Color-(uiimage*) Videopictureimageforreplacecolor: (uicolor*) color Tocolor: (uicolor*) Othercolor withimage: ( uiimage*) Image withdifference: (unsignedChar) difference{cvpixelbufferref pixelbuffer=NULL; Cgimageref img=image.    Cgimage; size_t width=cgimagegetwidth (IMG); size_t Height=cgimagegetheight (IMG); Cvreturn Status= Cvpixelbuffercreate (kcfallocatordefault, width, height, kcvpixelformattype_32bgra, nil, &Pixelbuffer); if(Status! =kcvreturnsuccess) {        returnNULL; } size_t rowbytes=Cvpixelbuffergetbytesperrow (Pixelbuffer); Cvpixelbufferlockbaseaddress (Pixelbuffer,0); void*data =cvpixelbuffergetbaseaddress (Pixelbuffer);    CGFloat R,g,b,a; [Othercolor getred:&r green:&g blue:&b alpha:&a]; Cgcolorspaceref Rgbcolorspace=Cgcolorspacecreatedevicergb (); Cgcontextref Context= Cgbitmapcontextcreate (data, width, height,8, Rowbytes, Rgbcolorspace, (cgbitmapinfo) kcgbitmapbyteorder32little |Kcgimagealphapremultipliedfirst); Cgcontextclearrect (Context, CGRectMake (0,0, width, height)); Cgcontextdrawimage (Context, CGRectMake (0,0, width, height), img); unsignedChar*colorptr = (unsignedChar*) data;  for(size_t h =0; h < height; h++) {         for(size_t w =0; W < width; w++) {                        if([Self Besimilarcolor:[uicolor colorwithred:colorptr[0]/255.0fgreen:colorptr[1]/255.0fblue:colorptr[2]/255.0falpha:colorptr[3]/255.0f] Withcolor:color withdifference:difference]) {//printf ("%d%d%d\n", colorptr[0],colorptr[1],colorptr[2],colorptr[3]);colorptr[0] = Round (r*255); colorptr[1] = Round (g*255); colorptr[2] = Round (b*255); colorptr[3] = Round (A *255); } colorptr+=4; }} cgimageref Imageref=cgbitmapcontextcreateimage (context);    Cgcolorspacerelease (Rgbcolorspace);    Cgcontextrelease (context); Cvpixelbufferunlockbaseaddress (Pixelbuffer,0); UIImage*returnimage =[UIImage Imagewithcgimage:imageref]; // Clean Upcgimagerelease (IMAGEREF);    Cvpixelbufferrelease (Pixelbuffer); returnreturnimage;}

Replace a color value of an image