给图片增加滤镜有这两种方式: CoreImage / openGLES
Cirelmage
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:
代码语言：javascript复制 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:
代码语言：javascript复制 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];openGLES
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:
代码语言：javascript复制 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
代码语言：javascript复制[filter setValue:vaule forKey:kCIInputIntensityKey];
