Im tr开发者_高级运维ying to find a way to programme/buy an app to use the iphone to detect someones skin tone against an objective scale using RGB froma phot they take of themselves. Anyone got any pointers?
I think the objections to this are correct - its going to be pretty hard work to calibrate it. However, any solution is going to rely on being able to get the colour of a specific pixel in an image (in this case a UIImageView...)
- (UIColor*) getPixelColorAtLocation:(CGPoint)point {
UIColor* color = nil;
CGImageRef inImage = self.image.CGImage;
// Create off screen bitmap context to draw the image into. Format ARGB is 4 bytes for each pixel: Alpa, Red, Green, Blue
CGContextRef cgctx = [self createARGBBitmapContextFromImage:inImage];
if (cgctx == NULL) { return nil; /* error */ }
size_t w = CGImageGetWidth(inImage);
size_t h = CGImageGetHeight(inImage);
CGRect rect = {{0,0},{w,h}};
// Draw the image to the bitmap context. Once we draw, the memory
// allocated for the context for rendering will then contain the
// raw image data in the specified color space.
CGContextDrawImage(cgctx, rect, inImage);
// Now we can get a pointer to the image data associated with the bitmap
// context.
unsigned char* data = CGBitmapContextGetData (cgctx);
if (data != NULL) {
//offset locates the pixel in the data from x,y.
//4 for 4 bytes of data per pixel, w is width of one row of data.
int offset = 4*((w*round(point.y))+round(point.x));
int alpha = data[offset];
int red = data[offset+1];
int green = data[offset+2];
int blue = data[offset+3];
NSLog(@"offset: %i colors: RGB A %i %i %i %i",offset,red,green,blue,alpha);
color = [UIColor colorWithRed:(red/255.0f) green:(green/255.0f) blue:(blue/255.0f) alpha:(alpha/255.0f)];
}
// When finished, release the context
CGContextRelease(cgctx);
// Free image data memory for the context
if (data) { free(data); }
return color;
}
This code is from a colourPicker class which carries the following (c)
// Created by markj on 3/6/09. // Copyright 2009 Mark Johnson. All rights reserved.
The full article is here http://www.markj.net/iphone-uiimage-pixel-color/
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