使用CoreImage教程

CoreImage包含有很多实用的滤镜,专业处理图片的库,为了能看到各种渲染效果,请使用如下图片素材.

现在可以开始教程了:

#define FIX_IMAGE(image)  fixImageWidth(image, 320.f)// 固定图片的宽度
UIImage * fixImageWidth(UIImage *image, CGFloat width)
{float newHeight = image.size.height * (width / image.size.width);CGSize size = CGSizeMake(width, newHeight);UIGraphicsBeginImageContextWithOptions(size, NO, 0);CGContextRef context = UIGraphicsGetCurrentContext();CGContextTranslateCTM(context, 0.0, size.height);CGContextScaleCTM(context, 1.0, -1.0);CGContextSetBlendMode(context, kCGBlendModeCopy);CGContextDrawImage(context, CGRectMake(0.0f, 0.0f, size.width, size.height),image.CGImage);UIImage *imageOut = UIGraphicsGetImageFromCurrentImageContext();UIGraphicsEndImageContext();return imageOut;
}代码片段

// 将UIImage转换成CIImageCIImage *ciImage = [[CIImage alloc] initWithImage:[UIImage imageNamed:@"1.jpg"]];// 创建滤镜CIFilter *filter = [CIFilter filterWithName:@"CIPhotoEffectMono"keysAndValues:kCIInputImageKey, ciImage, nil];[filter setDefaults];// 获取绘制上下文CIContext *context = [CIContext contextWithOptions:nil];// 渲染并输出CIImageCIImage *outputImage = [filter outputImage];// 创建CGImage句柄CGImageRef cgImage = [context createCGImage:outputImagefromRect:[outputImage extent]];// 获取图片UIImage *showImage = [UIImage imageWithCGImage:cgImage];// 释放CGImage句柄CGImageRelease(cgImage);// 显示图片UIImageView *imageView = \[[UIImageView alloc] initWithImage:FIX_IMAGE(showImage)];[self.view addSubview:imageView];代码片段

效果如下:

我们对操作进行简易的封装:

CIFilterEffect.h + CIFilterEffect.m

//
//  CIFilterEffect.h
//  CIFilter
//
//  Created by YouXianMing on 14-5-9.
//  Copyright (c) 2014年 Y.X. All rights reserved.
//#import <Foundation/Foundation.h>@interface CIFilterEffect : NSObject@property (nonatomic, strong, readonly) UIImage *result;- (instancetype)initWithImage:(UIImage *)image filterName:(NSString *)name;@end

//
//  CIFilterEffect.m
//  CIFilter
//
//  Created by YouXianMing on 14-5-9.
//  Copyright (c) 2014年 Y.X. All rights reserved.
//#import "CIFilterEffect.h"@interface CIFilterEffect ()@property (nonatomic, strong, readwrite) UIImage *result;@end@implementation CIFilterEffect- (instancetype)initWithImage:(UIImage *)image filterName:(NSString *)name
{self = [super init];if (self){// 将UIImage转换成CIImageCIImage *ciImage = [[CIImage alloc] initWithImage:image];// 创建滤镜CIFilter *filter = [CIFilter filterWithName:namekeysAndValues:kCIInputImageKey, ciImage, nil];[filter setDefaults];// 获取绘制上下文CIContext *context = [CIContext contextWithOptions:nil];// 渲染并输出CIImageCIImage *outputImage = [filter outputImage];// 创建CGImage句柄CGImageRef cgImage = [context createCGImage:outputImagefromRect:[outputImage extent]];_result = [UIImage imageWithCGImage:cgImage];// 释放CGImage句柄CGImageRelease(cgImage);}return self;
}@end

我们来开始尝试其他的滤镜效果,我们可以尝试的至少有这些:

@"CILinearToSRGBToneCurve",
@"CIPhotoEffectChrome",
@"CIPhotoEffectFade",
@"CIPhotoEffectInstant",
@"CIPhotoEffectMono",
@"CIPhotoEffectNoir",
@"CIPhotoEffectProcess",
@"CIPhotoEffectTonal",
@"CIPhotoEffectTransfer",
@"CISRGBToneCurveToLinear",
@"CIVignetteEffect",