Swift - 讀取.jpg圖像的像素顏色返回不正確的值

我想從swift中的jpg圖像中獲取每個像素的UIColor，下面的代碼成功獲取每個像素的顏色但是結果令我困惑：Swift - 讀取.jpg圖像的像素顏色返回不正確的值

func renderLandscape() { 

    var landscapeImage = UIImage(named: "test") 

    for var xPos = 0 as CGFloat; xPos < landscapeImage?.size.width; xPos++ { 
     for var yPos = 0 as CGFloat; yPos < landscapeImage?.size.height; yPos++ { 
      var currentColor = landscapeImage?.getPixelColor(CGPointMake(xPos, yPos)) 
      NSLog("Color: %@", currentColor!) 
     } 
    } 
}

我創建的UIImage的延伸位置：

extension UIImage { 
    func getPixelColor(pos: CGPoint) -> UIColor { 

     var pixelData = CGDataProviderCopyData(CGImageGetDataProvider(self.CGImage)) 
     var data: UnsafePointer<UInt8> = CFDataGetBytePtr(pixelData) 

     var pixelInfo: Int = ((Int(self.size.width) * Int(pos.y)) + Int(pos.x)) * 4 

     //NSLog("Data: %@", data.encode()) 

     var r = CGFloat(data[pixelInfo])/CGFloat(255.0) 
     var g = CGFloat(data[pixelInfo+1])/CGFloat(255.0) 
     var b = CGFloat(data[pixelInfo+2])/CGFloat(255.0) 
     var a = CGFloat(data[pixelInfo+3])/CGFloat(255.0) 

     return UIColor(red: r, green: g, blue: b, alpha: a) 
    } 
}

顯然的輸出是極長然而這裏是第41線（圖像的第一列）：

2015-05-12 22:21:58.793 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.793 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.794 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.794 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.794 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.794 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.794 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.794 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.794 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.794 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.795 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.795 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.795 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.797 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.798 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.798 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.798 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.798 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.798 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.799 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.799 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.799 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.799 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.799 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.814 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.814 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.814 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.814 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.814 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.814 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.815 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.815 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.815 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0 0 1 
2015-05-12 22:21:58.815 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0.00392157 0 1 
2015-05-12 22:21:58.815 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0.00392157 0 1 
2015-05-12 22:21:58.830 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0.0470588 0 1 
2015-05-12 22:21:58.831 Game[6542:220967] Color: UIDeviceRGBColorSpace 0 0.141176 0 1 
2015-05-12 22:21:58.831 Game[6542:220967] Color: UIDeviceRGBColorSpace 0.627451 0.694118 0.317647 1 
2015-05-12 22:21:58.832 Game[6542:220967] Color: UIDeviceRGBColorSpace 0.756863 0.121569 0 1 
2015-05-12 22:21:58.832 Game[6542:220967] Color: UIDeviceRGBColorSpace 0.996078 0 0 1 
2015-05-12 22:21:58.832 Game[6542:220967] Color: UIDeviceRGBColorSpace 0.996078 0.00392157 0 1

拳頭32線是UIDeviceRGBColorSpace 0 0 0 1，這是正確的（黑色）之後但是，應該有四個黑像素的綠色（#2aff00）和三個紅（#ff0000）除了有8個非黑色像素，每一個不同的顏色值。

這裏是一個是在Photoshop中創建的圖像：

enter image description here

爲什麼沒有任何紅顏色的RGB相同，爲什麼會有8個非黑色像素？

在此先感謝，約翰

來源

2015-05-13 Johann Burgess

好了，所以之後我掙扎着試圖救了我的圖像作爲PNG文件的公平位。修復了一切。

據朋友JPG圖像像素顏色之間的模糊種類，其中PNG將保持每個像素的純色。使用PNG這種工作更可靠。 - 請原諒我的非技術性談話。

謝謝。

來源

2015-05-15 12:24:33

Swift - 讀取.jpg圖像的像素顏色返回不正確的值

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