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:

 1 　　//导入CIImage
 2     CIImage *ciImage = [[CIImage alloc] initWithImage:[UIImage imageNamed:@"hua"]];
 3
 4     //创建出Filter滤镜
 5     CIFilter *filter = [CIFilter filterWithName:@"CIPixellate"];
 6
 7     [filter setValue:ciImage forKey:kCIInputImageKey];
 8
 9     [filter setDefaults];
10
11     CIImage *outImage = [filter valueForKey:kCIOutputImageKey];
12
13     //用CIContext将滤镜中的图片渲染出来
14     CIContext *context = [CIContext contextWithOptions:nil];
15
16     CGImageRef cgImage = [context createCGImage:outImage
17                                        fromRect:[outImage extent]];
18
19     //导出图片
20     UIImage *showImage = [UIImage imageWithCGImage:cgImage];
21
22     CGImageRelease(cgImage);
23
24     UIImageView *imageView = [[UIImageView alloc] initWithImage:showImage];
25     imageView.center       = self.view.center;
26     [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:

 1 //导入CIImage
 2     CIImage *ciImage = [[CIImage alloc] initWithImage:[UIImage imageNamed:@"hua.jpeg"]];
 3
 4     //创建出Filter滤镜
 5     CIFilter *filter = [CIFilter filterWithName:@"CIPixellate"];
 6
 7     [filter setValue:ciImage forKey:kCIInputImageKey];
 8
 9     [filter setDefaults];
10
11     CIImage *outImage = [filter valueForKey:kCIOutputImageKey];
12
13     CIFilter *filterTwo = [CIFilter filterWithName:@"CIHueAdjust"];
14
15     [filterTwo setValue:outImage forKey:kCIInputImageKey];
16
17     [filterTwo setDefaults];
18
19     [filterTwo setValue:@(1.0f) forKey:kCIInputAngleKey]; //如果不增加这行新增的滤镜不会生效
20
21     CIImage *outputImage = [filterTwo valueForKey:kCIOutputImageKey];
22
23     //用CIContext将滤镜中的图片渲染出来
24     CIContext *context = [CIContext contextWithOptions:nil];
25
26     CGImageRef cgImage = [context createCGImage:outputImage
27                                        fromRect:[outputImage extent]];
28
29     //导出图片
30     UIImage *showImage = [UIImage imageWithCGImage:cgImage];
31
32     CGImageRelease(cgImage);
33
34     UIImageView *imageView = [[UIImageView alloc] initWithImage:showImage];
35     imageView.center       = self.view.center;
36     [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:

 1 //导入要渲染的图片
 2     UIImage *showImage = [UIImage imageNamed:@"hua.jpeg"];
 3     CGRect rect        = CGRectMake(0, 0, showImage.size.width, showImage.size.height);
 4
 5     //获取OpenGLES渲染的上下文
 6     EAGLContext *eagContext = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2];
 7
 8     //创建出渲染的buffer
 9     GLKView *glkView = [[GLKView alloc] initWithFrame:rect
10                                               context:eagContext];
11     [glkView bindDrawable];
12     [self.view addSubview:glkView];
13
14     //创建出CoreImage的上下文
15     CIContext *ciContext = [CIContext contextWithEAGLContext:eagContext
16                                                      options:@{kCIContextWorkingColorSpace: [NSNull null]}];
17
18     //CoreImage相关设置
19     CIImage *ciImage = [[CIImage alloc] initWithImage:showImage];
20
21     CIFilter *filter = [CIFilter filterWithName:@"CISepiaTone"];
22
23     [filter setValue:ciImage forKey:kCIInputImageKey];
24     [filter setValue:@(0) forKey:kCIInputIntensityKey];
25
26     //开始渲染
27     [ciContext drawImage:[filter valueForKey:kCIOutputImageKey]
28                   inRect:CGRectMake(0, 0, glkView.drawableWidth, glkView.drawableHeight)
29                 fromRect:[ciImage extent]];
30
31     [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];