前言
iOS16 推出的一键抠图功能，还是挺有趣的，我猜想它可能是通过 Vision 实现的（毕竟 Vision 在最新的开发者大会上也介绍了新的更新），于是想试试看我能不能找到抠图的办法。
实现
具体的思路其实就是借助 Vision 帮助我找到图片中的热力图，然后检测出热力图中显著区域的边缘，并把得到的结果转化为图片上的坐标，然后进行抠图
得到热力图
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| UIImage *originImage = [UIImage imageNamed:@"test.jpg"];
CIImage *ciOriginImg = [CIImage imageWithCGImage:originImage.CGImage];//原始图片
VNImageRequestHandler *imageHandler = [[VNImageRequestHandler alloc] initWithCIImage:ciOriginImg options:@{}];
VNGenerateObjectnessBasedSaliencyImageRequest *attensionRequest = [[VNGenerateObjectnessBasedSaliencyImageRequest alloc] init];//基于物体的显著性区域检测请求
NSError *err = nil;
BOOL haveAttension = [imageHandler performRequests:@[attensionRequest] error:&err];//有物品
if ( haveAttension ) {//有物品
if(attensionRequest.results && [attensionRequest.results count] > 0) {
VNSaliencyImageObservation *observation = [attensionRequest.results firstObject];
/// 热力图
CIImage *heatImage = [CIImage imageWithCVPixelBuffer:observation.pixelBuffer];
}
}
|
热力图边缘检测
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| - (void)heatMapProcess:(CVImageBufferRef)hotRef catOrigin:(CIImage *)catOrigin {
CIImage *heatImage = [CIImage imageWithCVPixelBuffer:hotRef];
VNDetectContoursRequest *contourRequest = [[VNDetectContoursRequest alloc] init];
contourRequest.revision = VNDetectContourRequestRevision1;
contourRequest.contrastAdjustment = 1.0;
contourRequest.detectsDarkOnLight = NO;
contourRequest.maximumImageDimension = 512;
VNImageRequestHandler *handler = [[VNImageRequestHandler alloc] initWithCIImage:heatImage options:@{}];
NSError *err = nil;
BOOL result = [handler performRequests:@[contourRequest] error:&err];
if(result) {
/// 边缘检测结果
VNContoursObservation *contoursObv = [contourRequest.results firstObject];
CIContext *cxt = [[CIContext alloc] initWithOptions:nil];
CGImageRef origin = [cxt createCGImage:catOrigin fromRect:catOrigin.extent];
}
}
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抠图
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| - (UIImage *)drawContourWith:(VNContoursObservation *)contourObv withCgImg:(CGImageRef)img originImg:(CGImageRef)origin{
CGSize size = CGSizeMake(CGImageGetWidth(origin), CGImageGetHeight(origin));
UIImageView *originImgV = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, size.width, size.height)];
originImgV.image = [UIImage imageWithCGImage:origin];
CAShapeLayer *layer = [CAShapeLayer layer];
CGAffineTransform flipMatrix = CGAffineTransformMake(1, 0, 0, -1, 0, size.height);//坐标转换为底部为（0， 0）
CGAffineTransform scaleTranform = CGAffineTransformScale(flipMatrix, size.width, size.height); //对path 进行按图尺寸放大
CGPathRef scaedPath = CGPathCreateCopyByTransformingPath(contourObv.normalizedPath, &scaleTranform);//对归一化的path进行变换
layer.path = scaedPath;
[originImgV.layer setMask:layer];
UIGraphicsBeginImageContext(originImgV.bounds.size);
[originImgV.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}
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总结
从我测试的抠图的结果来看，效果还是有些瑕疵的，我也从更新了 iOS16 的小伙伴那里，体验了一下原生抠图的效果，看起来和我的差不多，都还有些瑕疵，看来进步的空间还很大～
参考
Vision
