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];

滤镜有哪些可选可以参看以下文章:http://www.jianshu.com/p/3e2cca585ccc

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, 代码如下:

 //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

参考代码如下:

 //导入要渲染的图片
     UIImage *showImage = [UIImage imageNamed:@"hua.jpeg"];
     CGRect rect        = CGRectMake(, , showImage.size.width, showImage.size.height);

     //获取OpenGLES渲染的上下文
     EAGLContext *eagContext = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2];

     //创建出渲染的buffer
     GLKView *glkView = [[GLKView alloc] initWithFrame:rect
                                               context:eagContext];
     [glkView bindDrawable];
     [self.view addSubview:glkView];

     //创建出CoreImage的上下文
     CIContext *ciContext = [CIContext contextWithEAGLContext:eagContext
                                                      options:@{kCIContextWorkingColorSpace: [NSNull null]}];

     //CoreImage相关设置
     CIImage *ciImage = [[CIImage alloc] initWithImage:showImage];

     CIFilter *filter = [CIFilter filterWithName:@"CISepiaTone"];

     [filter setValue:ciImage forKey:kCIInputImageKey];
     [filter setValue:@() forKey:kCIInputIntensityKey];

     //开始渲染
     [ciContext drawImage:[filter valueForKey:kCIOutputImageKey]
                   inRect:CGRectMake(, , glkView.drawableWidth, glkView.drawableHeight)
                 fromRect:[ciImage extent]];

     [glkView display];

如果要动态渲染, 可以通过UISilder动态调整一下代码的vaule值

[filter setValue:vaule forKey:kCIInputIntensityKey];