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POCreate a mask from difference between two images (iPhone)
 

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  1. POCreate a mask from difference between two images (iPhone)
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    <p>How can I detect the difference between 2 images, creating a mask of the area that's different in order to process the area that's common to both images (gaussian blur for example)?</p> <p><img src="https://i.stack.imgur.com/dICyo.png" alt="sketch"></p> <p><strong>EDIT:</strong> I'm currently using this code to get the RGBA value of pixels:</p> <pre><code>+ (NSArray*)getRGBAsFromImage:(UIImage*)image atX:(int)xx andY:(int)yy count:(int)count { NSMutableArray *result = [NSMutableArray arrayWithCapacity:count]; // First get the image into your data buffer CGImageRef imageRef = [image CGImage]; NSUInteger width = CGImageGetWidth(imageRef); NSUInteger height = CGImageGetHeight(imageRef); CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); unsigned char *rawData = malloc(height * width * 4); NSUInteger bytesPerPixel = 4; NSUInteger bytesPerRow = bytesPerPixel * width; NSUInteger bitsPerComponent = 8; CGContextRef context = CGBitmapContextCreate(rawData, width, height, bitsPerComponent, bytesPerRow, colorSpace, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big); CGColorSpaceRelease(colorSpace); CGContextDrawImage(context, CGRectMake(0, 0, width, height), imageRef); CGContextRelease(context); // Now your rawData contains the image data in the RGBA8888 pixel format. int byteIndex = (bytesPerRow * yy) + xx * bytesPerPixel; for (int ii = 0 ; ii &lt; count ; ++ii) { CGFloat red = (rawData[byteIndex] * 1.0) / 255.0; CGFloat green = (rawData[byteIndex + 1] * 1.0) / 255.0; CGFloat blue = (rawData[byteIndex + 2] * 1.0) / 255.0; CGFloat alpha = (rawData[byteIndex + 3] * 1.0) / 255.0; byteIndex += 4; UIColor *acolor = [UIColor colorWithRed:red green:green blue:blue alpha:alpha]; [result addObject:acolor]; } free(rawData); return result; } </code></pre> <p>The problem is, the images are being captured from the iPhone's camera so they are not exactly the same position. I need to create areas of a couple of pixels and extracting the general color of the area (maybe by adding up the RGBA values and dividing by the number of pixels?). How could I do this and then translate it to a CGMask?</p> <p>I know this is a complex question, so any help is appreciated.</p> <p>Thanks. </p>
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