ios - 比较两个图像并找出差异百分比

Question

我一直在尝试通过图像制作一个动物识别应用程序。我的方法是将所选图像与图像数组中的其他图像进行比较，并列出相似度超过 90% 的所有比较。还有其他方法可以比较两个相似但不相似的图像吗？任何建议，将不胜感激。这些计算还必须运行多次迭代，因此非常感谢不耗时的方法。

请尝试提供一些带有答案的代码，因为我对 Swift 经验不是很丰富。

Answer 1

您可以像我一样通过分析一帧到下一帧并对差异进行阈值处理(我还没有缩小图像，可能应该)

// called everytime a frame is captured
func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {

    guard let imageBufferRef = CMSampleBufferGetImageBuffer(sampleBuffer) else {
        return
    }

    CVPixelBufferLockBaseAddress(imageBufferRef, []);

    // set up for comparisons between prev and next images
    if prevPB == nil {
        prevPB = imageBufferRef
    }

    if (!isPlaying && motionIsDetected(prevPB, imageBufferRef) == 1) {
        isPlaying = true
        print("play video")
    }
    CVPixelBufferUnlockBaseAddress(imageBufferRef,[]);


    // if true, play the video
    prevPB = imageBufferRef
}


func pixelFrom(x: Int, y: Int, current: CVPixelBuffer) -> (UInt8, UInt8, UInt8) {
    let baseAddress = CVPixelBufferGetBaseAddress(current)
    let bytesPerRow = CVPixelBufferGetBytesPerRow(current)
    let buffer = baseAddress!.assumingMemoryBound(to: UInt8.self)
    let index = x*bytesPerRow+y

    let b = buffer[index]
    let g = buffer[index+1]
    let r = buffer[index+2]

    return (r, g, b)
}

func motionIsDetected(_ prev:CVPixelBuffer, _ current:CVPixelBuffer) -> Int {

    var differences = 0

    let baseAddress = CVPixelBufferGetBaseAddress(current)

    let width = CVPixelBufferGetWidth(current)
    let height = CVPixelBufferGetHeight(current)


    // THRESHOLDING: clamp by abs(aa-bb) for tuple of r,b,g  if 150 difference and at least 10 different pixels
    var MAGIC_THRESHOLD = 120
    var ENOUGH_DIFFERENCES = 10

    if (current != nil && prev != nil) {
        for x in 0..<height { //rows
            for y in 0..<width { //cols
                var setA = pixelFrom(x: x, y: y, current: prev)
                var setB = pixelFrom(x: x, y: y, current: current)
                if abs(Int(setA.0) - Int(setB.0)) > MAGIC_THRESHOLD && abs(Int(setA.1) - Int(setB.1)) > MAGIC_THRESHOLD && abs(Int(setA.2) - Int(setB.2)) > MAGIC_THRESHOLD {
                    differences = differences + 1
                }
            }
        }
    }
    print(" difference" )
    print(differences)

    if differences > ENOUGH_DIFFERENCES {
        return 1
    }
    return 0

}