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];