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];

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];

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