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(0, 0, 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:@(0) forKey:kCIInputIntensityKey];
//开始渲染
[ciContext drawImage:[filter valueForKey:kCIOutputImageKey]
inRect:CGRectMake(0, 0, 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];
