我有以下UIImage:
任何帮助都将不胜感激。
任何帮助都将不胜感激。
使用CIContext
代替-UIImage:CIImage
(请参阅https://dev59.com/gIfca4cB1Zd3GeqPlqY6#28386697),并在@wtznc的回答的基础上构建,这里是一个自包含的IBDesignable:
@IBDesignable
class InvertImage: UIImageView {
@IBInspectable var originalImage:UIImage? = nil
@IBInspectable var invert:Bool = false {
didSet {
var inverted = false
if let originalImage = self.originalImage {
if(invert) {
let image = CIImage(CGImage: originalImage.CGImage!)
if let filter = CIFilter(name: "CIColorInvert") {
filter.setDefaults()
filter.setValue(image, forKey: kCIInputImageKey)
let context = CIContext(options: nil)
let imageRef = context.createCGImage(filter.outputImage!, fromRect: image.extent)
self.image = UIImage(CGImage: imageRef)
inverted = true
}
}
}
if(!inverted) {
self.image = self.originalImage
}
}
}
}
extension UIImage {
func invertedImage() -> UIImage? {
guard let cgImage = self.cgImage else { return nil }
let ciImage = CoreImage.CIImage(cgImage: cgImage)
guard let filter = CIFilter(name: "CIColorInvert") else { return nil }
filter.setDefaults()
filter.setValue(ciImage, forKey: kCIInputImageKey)
let context = CIContext(options: nil)
guard let outputImage = filter.outputImage else { return nil }
guard let outputImageCopy = context.createCGImage(outputImage, from: outputImage.extent) else { return nil }
return UIImage(cgImage: outputImageCopy, scale: self.scale, orientation: .up)
}
}
- (UIImage *)negativeImage
{
// get width and height as integers, since we'll be using them as
// array subscripts, etc, and this'll save a whole lot of casting
CGSize size = self.size;
int width = size.width;
int height = size.height;
// Create a suitable RGB+alpha bitmap context in BGRA colour space
CGColorSpaceRef colourSpace = CGColorSpaceCreateDeviceRGB();
unsigned char *memoryPool = (unsigned char *)calloc(width*height*4, 1);
CGContextRef context = CGBitmapContextCreate(memoryPool, width, height, 8, width * 4, colourSpace, kCGBitmapByteOrder32Big | kCGImageAlphaPremultipliedLast);
CGColorSpaceRelease(colourSpace);
// draw the current image to the newly created context
CGContextDrawImage(context, CGRectMake(0, 0, width, height), [self CGImage]);
// run through every pixel, a scan line at a time...
for(int y = 0; y < height; y++)
{
// get a pointer to the start of this scan line
unsigned char *linePointer = &memoryPool[y * width * 4];
// step through the pixels one by one...
for(int x = 0; x < width; x++)
{
// get RGB values. We're dealing with premultiplied alpha
// here, so we need to divide by the alpha channel (if it
// isn't zero, of course) to get uninflected RGB. We
// multiply by 255 to keep precision while still using
// integers
int r, g, b;
if(linePointer[3])
{
r = linePointer[0] * 255 / linePointer[3];
g = linePointer[1] * 255 / linePointer[3];
b = linePointer[2] * 255 / linePointer[3];
}
else
r = g = b = 0;
// perform the colour inversion
r = 255 - r;
g = 255 - g;
b = 255 - b;
if ( (r+g+b) / (3*255) == 0 )
{
linePointer[0] = linePointer[1] = linePointer[2] = 0;
linePointer[3] = 0;
}
else
{
// multiply by alpha again, divide by 255 to undo the
// scaling before, store the new values and advance
// the pointer we're reading pixel data from
linePointer[0] = r * linePointer[3] / 255;
linePointer[1] = g * linePointer[3] / 255;
linePointer[2] = b * linePointer[3] / 255;
}
linePointer += 4;
}
}
// get a CG image from the context, wrap that into a
// UIImage
CGImageRef cgImage = CGBitmapContextCreateImage(context);
UIImage *returnImage = [UIImage imageWithCGImage:cgImage];
// clean up
CGImageRelease(cgImage);
CGContextRelease(context);
free(memoryPool);
// and return
return returnImage;
}
我在UIImage扩展类中添加了上述方法。
#import <CoreImage/CoreImage.h>
初始化一个UIImage
对象来存储原始文件。
UIImage *inputImage = [UIImage imageNamed:@"imageNamed"];
CIFilter
,定义您想要如何修改原始的 UIImage
对象。CIFilter* filter = [CIFilter filterWithName:@"CIColorInvert"];
[filter setDefaults];
[filter setValue:inputImage.CIImage forKey:@"inputImage"];
UIImage
对象来保存修改后的图像。UIImage *outputImage = [[UIImage alloc] initWithCIImage:filter.outputImage];
完成!希望能对您有所帮助。
针对 Xamarin C#(仅限iOS,不是跨平台解决方案):
public static UIImage InvertImageColors( UIImage original )
{
return ApplyFilter( original, new CIColorInvert() );
}
public static UIImage ApplyFilter( UIImage original, CIFilter filter )
{
UIImage result;
try {
CIImage coreImage = original.CGImage;
filter.SetValueForKey( coreImage, CIFilterInputKey.Image );
CIImage output = filter.OutputImage;
CIContext context = CIContext.FromOptions( null );
CGImage cgImage = context.CreateCGImage( output, output.Extent );
result = UIImage.FromImage( cgImage );
} catch (Exception ex) {
// .. Log error here ..
result = original;
}
return result;
}
注意1:这是从别人的回答中改编而来,我已经追不上原始来源了。
注意2:故意每行只做一小步,以便您可以看到中间类型,并轻松地适应其他情况。