iOS给图片添加滤镜&使用openGLES动态渲染图片
给图片增加滤镜有这两种方式: CoreImage / openGLES
下面先说明如何使用CoreImage给图片添加滤镜, 主要为以下步骤:
#1.导入CIImage格式的原始图片
#2.创建CIFilter滤镜
#3.用CIContext将滤镜中的图片渲染出来
#4.导出渲染后的图片
参考代码:
//导入CIImage
CIImage *ciImage = [[CIImage alloc] initWithImage:[UIImage imageNamed:@"hua"]];
//创建出Filter滤镜
CIFilter *filter = [CIFilter filterWithName:@"CIPixellate"];
[filter setValue:ciImage forKey:kCIInputImageKey];
[filter setDefaults];
CIImage *outImage = [filter valueForKey:kCIOutputImageKey];
//用CIContext将滤镜中的图片渲染出来
CIContext *context = [CIContext contextWithOptions:nil];
CGImageRef cgImage = [context createCGImage:outImage
fromRect:[outImage extent]];
//导出图片
UIImage *showImage = [UIImage imageWithCGImage:cgImage];
CGImageRelease(cgImage);
UIImageView *imageView = [[UIImageView alloc] initWithImage:showImage];
imageView.center = self.view.center;
[self.view addSubview:imageView];
当要设置多个滤镜的时候, 出了新创建一个CIFilter外还要额外设定kCIInputAngleKey,
//导入CIImage
CIImage *ciImage = [[CIImage alloc] initWithImage:[UIImage imageNamed:@"hua.jpeg"]];
//创建出Filter滤镜
CIFilter *filter = [CIFilter filterWithName:@"CIPixellate"];
[filter setValue:ciImage forKey:kCIInputImageKey];
[filter setDefaults];
CIImage *outImage = [filter valueForKey:kCIOutputImageKey];
CIFilter *filterTwo = [CIFilter filterWithName:@"CIHueAdjust"];
[filterTwo setValue:outImage forKey:kCIInputImageKey];
[filterTwo setDefaults];
[filterTwo setValue:@(1.0f) forKey:kCIInputAngleKey]; //如果不增加这行新增的滤镜不会生效
CIImage *outputImage = [filterTwo valueForKey:kCIOutputImageKey];
//用CIContext将滤镜中的图片渲染出来
CIContext *context = [CIContext contextWithOptions:nil];
CGImageRef cgImage = [context createCGImage:outputImage
fromRect:[outputImage extent]];
//导出图片
UIImage *showImage = [UIImage imageWithCGImage:cgImage];
CGImageRelease(cgImage);
UIImageView *imageView = [[UIImageView alloc] initWithImage:showImage];
imageView.center = self.view.center;
[self.view addSubview:imageView];
下面来介绍怎么用openGLES来使用滤镜渲染图片
使用openGlES的步骤大致如下:
#1.导入要渲染的图片
#2.获取OpenGLES渲染的上下文
#3.创建出渲染的GLKView buffer
#4.创建CoreImage的上下文
#5.进行CoreImage的相关设置
#6.开始渲染并显示图片
参考
