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Percentage difference between images: Difference between revisions
Percentage difference between images (view source)
Revision as of 22:06, 19 December 2016
, 7 years agoAdded Swift 3.0 version of algorithm
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(Added Swift 3.0 version of algorithm) |
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</pre>
=={{header|Swift}}==
<lang swift>func pixelValues(fromCGImage imageRef: CGImage?) -> [UInt8]?
{
var width = 0
var height = 0
var pixelValues: [UInt8]?
if let imageRef = imageRef {
width = imageRef.width
height = imageRef.height
let bitsPerComponent = imageRef.bitsPerComponent
let bytesPerRow = imageRef.bytesPerRow
let totalBytes = height * bytesPerRow
let bitmapInfo = imageRef.bitmapInfo
let colorSpace = CGColorSpaceCreateDeviceRGB()
var intensities = [UInt8](repeating: 0, count: totalBytes)
let contextRef = CGContext(data: &intensities,
width: width,
height: height,
bitsPerComponent: bitsPerComponent,
bytesPerRow: bytesPerRow,
space: colorSpace,
bitmapInfo: bitmapInfo.rawValue)
contextRef?.draw(imageRef, in: CGRect(x: 0.0, y: 0.0, width: CGFloat(width), height: CGFloat(height)))
pixelValues = intensities
}
return pixelValues
}
func compareImages(image1: UIImage, image2: UIImage) -> Double? {
guard let data1 = pixelValues(fromCGImage: image1.cgImage),
let data2 = pixelValues(fromCGImage: image2.cgImage),
data1.count == data2.count else {
return nil
}
let width = Double(image1.size.width)
let height = Double(image1.size.height)
return zip(data1, data2)
.enumerated()
.reduce(0.0) {
$1.offset % 4 == 3 ? $0 : $0 + abs(Double($1.element.0) - Double($1.element.1))
}
* 100 / (width * height * 3.0) / 255.0
}</lang>
=={{header|Tcl}}==
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