[英]CIFilter output image nil
I am using core image and I am applying a CIFilter sepia tone to my image. 我正在使用核心图像,我正在为我的图像应用CIFilter棕褐色调。 I run a filter once in viewDidLoad and then immediately call another function that adds the filter again.
我在viewDidLoad中运行一次过滤器,然后立即调用另一个再次添加过滤器的函数。 For some reason, when I try to access the output image, the app crashes and says the output image is nil.
出于某种原因,当我尝试访问输出图像时,应用程序崩溃并说输出图像为零。 Anyone know why this is happening?
任何人都知道为什么会这样吗?
Thanks 谢谢
import UIKit
class ViewController: UIViewController {
@IBOutlet weak var myimage: UIImageView!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
let image = CIImage(image: myimage.image)
let filter = CIFilter(name: "CISepiaTone")
filter.setDefaults()
filter.setValue(image, forKey: kCIInputImageKey)
myimage.image = UIImage(CIImage: filter.outputImage)
self.reapplyFilter()
}
func reapplyFilter(){
let image = CIImage(image: myimage.image)
let filter = CIFilter(name: "CISepiaTone")
filter.setDefaults()
filter.setVa lue(image, forKey: kCIInputImageKey)
//ERROR HERE: fatal error: unexpectedly found nil while unwrapping an Optional value
myimage.image = UIImage(CIImage: filter.outputImage)
//ERROR
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
You cannot call UIImage(CIImage:)
and use that UIImage as the image of a UIImageView. 你不能调用
UIImage(CIImage:)
并使用UIImage作为UIImageView的图像。 UIImageView requires a UIImage backed by a bitmap (CGImage). UIImageView需要一个由位图(CGImage)支持的UIImage。 A UIImage instantiated with CIImage has no bitmap;
用CIImage实例化的UIImage没有位图; it has no actual image, it's just a set of instructions for applying a filter.
它没有实际图像,它只是一组应用过滤器的指令。 That is why your UIImageView's image is nil.
这就是你的UIImageView图像为零的原因。
A couple of things here: 这里有几件事:
1) Using the CIImage constructor to create a CIImage based on a non CIImage backed UIImage is dangerous and will return nil or an empty CIImage. 1)使用CIImage构造函数基于非CIImage支持的UIImage创建CIImage是危险的,并且将返回nil或空CIImage。
2) When creating the image back I'd suggest you to use CIContext instead of UIImage(CIImage:). 2)当创建图像时,我建议你使用CIContext而不是UIImage(CIImage :)。
Example: 例:
class ViewController: UIViewController {
@IBOutlet weak var myimage: UIImageView!
override func viewDidLoad() {
super.viewDidLoad()
myimage.backgroundColor = UIColor.redColor()
self.applyFilter()
self.applyFilter()
}
func applyFilter(){
let image = CIImage(CGImage: myimage.image?.CGImage)
let filter = CIFilter(name: "CISepiaTone")
filter.setDefaults()
filter.setValue(image, forKey: kCIInputImageKey)
let context = CIContext(options: nil)
let imageRef = context.createCGImage(filter.outputImage, fromRect: image.extent())
myimage.image = UIImage(CGImage: imageRef)
}
}
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