IOS Gets the Color object (uicolor*) of a point in the picture.

-(uicolor *) Coloratpixel: (cgpoint) Point {

//Cancel If point is outside image coordinates

if (! Cgrectcontainspoint (cgrectmake(0.0f,0.0f, self. ) Size. width,self. size. ( height), point)) {

return Nil;

}

nsinteger pointx = trunc(point. x);

Nsinteger pointy = trunc(point. Y);

cgimageref cgimage = self. Cgimage;

nsuinteger width =self. Size. width;

nsuinteger height =self. Size. Height;

cgcolorspaceref colorspace =Cgcolorspacecreatedevicergb();

int bytesperpixel = 4;

int bytesperrow = bytesperpixel * 1;

nsuinteger bitspercomponent = 8;

unsigned Char pixeldata[4] = {0, 0, 0, 0 };

cgcontextref context = cgbitmapcontextcreate(Pixeldata,

1,

1,

Bitspercomponent,

Bytesperrow,

ColorSpace,

Kcgimagealphapremultipliedlast | kcgbitmapbyteorder32big);

cgcolorspacerelease(colorspace);

Cgcontextsetblendmode(context,kcgblendmodecopy);

//Draw The pixel we are interested in onto the bitmap context

CGCONTEXTTRANSLATECTM (Context,-pointx, pointy-(cgfloat) height);

Cgcontextdrawimage (Context, cgrectmake(0.0f, 0.0f, (cgfloat) width, (cgfloat) height), Cgimage);

cgcontextrelease(context);

//Convert color values [0..255] to floats [0.0..1.0]

cgfloat red = (cgfloat) pixeldata[0]/255.0f;

cgfloat green = (cgfloat) pixeldata[1]/255.0f;

cgfloat blue = (cgfloat) pixeldata[2]/255.0f;

cgfloat alpha = (cgfloat) pixeldata[3]/255.0f;

return [uicolorcolorwithred: Red green: Greenblue: Blue Alpha: Alpha];

}

Uiimage+coloratpixel.h #import <uikit/uikit.h>/* A category on UIImage This enables to query the color value of Arbitrary pixels of the image. */@interface UIImage (Coloratpixel)-(Uicolor *) Coloratpixel: (cgpoint) point; @end #import <coregraphics/ coregraphics.h> #import "Uiimage+coloratpixel.h" @implementation UIImage (Coloratpixel)-(Uicolor *) Coloratpixel: ( Cgpoint) point {//Cancel if point is outside image coordinates if (!    Cgrectcontainspoint (CGRectMake (0.0f, 0.0f, Self.size.width, Self.size.height), point)) {return nil;    } Nsinteger Pointx = Trunc (point.x);    Nsinteger pointy = trunc (POINT.Y); Cgimageref cgimage = self.    Cgimage;    Nsuinteger width = self.size.width;    Nsuinteger height = self.size.height;    Cgcolorspaceref colorspace = Cgcolorspacecreatedevicergb ();    int bytesperpixel = 4;    int bytesperrow = Bytesperpixel * 1;    Nsuinteger bitspercomponent = 8;    unsigned char pixeldata[4] = {0, 0, 0, 0}; Cgcontextref context = CgbitMapcontextcreate (Pixeldata, 1,                                                  1, Bitspercomponent,                                                 Bytesperrow, ColorSpace, Kcgimagealphapremultipliedlast |    KCGBITMAPBYTEORDER32BIG);    Cgcolorspacerelease (ColorSpace);    Cgcontextsetblendmode (context, kcgblendmodecopy); Draw The pixel we is interested in onto the bitmap context Cgcontexttranslatectm (context,-pointx, pointy-(cgfloat)    height);    Cgcontextdrawimage (Context, CGRectMake (0.0f, 0.0f, (cgfloat) width, (cgfloat) height), cgimage);        Cgcontextrelease (context);    Convert color values [0..255] to floats [0.0..1.0] cgfloat red = (cgfloat) pixeldata[0]/255.0f;    CGFloat green = (cgfloat) pixeldata[1]/255.0f;    CGFloat blue = (cgfloat) pixeldata[2]/255.0f; CgfloAt alpha = (cgfloat) pixeldata[3]/255.0f; return [Uicolor colorwithred:red green:green blue:blue alpha:alpha];} @end

IOS Gets the Color object (uicolor*) of a point in the picture.