人脸识别技术概念

所谓人脸识别技术，即基于人的脸部特征，对输入的人脸图象或者视频流进行判断，首先判断其是否存在人脸。如果存在人脸，则进一步的给出每个脸的位置、大小和各个主要面部器官的位置信息。并依据这些信息，进一步提取每个人脸中所蕴涵的身份特征，并将其与已知的人脸进行对比，从而识别每个人脸的身份。

人脸识别技术的发展前景

在这个刷脸的时代,人脸识别技术怎能不火。人脸识别技术，是目前生物科技上在可行性，稳定性和准确性等专业技术指标中数值最高的技术。也是目前各行各业安全保卫中运用最广，效果最好的一种技术。在未来的几年内，它必将超越指纹识别等生物技术，成为生物识别技术领域的霸主。

列举人脸识别在手机APP上的一些应用

1.美图秀秀邪恶大测试:识别面部表情,给出分数和评价
2.百度图片识图功能
3.百度魔图APP推出了“PK大咖”功能，用户只需要选取一张自己的大头照，就可以通过人脸识别技术跟明星进行PK，找到与你面部形象最为相似的明星大咖
4.百度钱包APP拍照付只是说当你想买一款商品，却不知道商品的具体信息，这时候就可以用到百度钱包的拍照付，拍一下就能搜索到商品，选择购买
5.支付宝APP人脸识别登录
6.iPhoto 在苹果的iPhoto中，同样提供了人脸识别功能，用户可以将图片中的人脸和人名相匹配，该功能通过脸部检测辨别照片中的人物，再通过脸部识别找到与之特征相符的拍摄对象，帮你找到想找的人，甚至是海量的照片库也不费吹灰之力
7.图图搜是先找到淘宝上的同款，然后拿到产品tag，接着根据tag、主颜色等信息进行二次查找。最基本的技术还是相同图像查找，当然也包含了商品主体识别。

Face++ 人脸识别demo

主要实现的功能是:给出两张面孔,判断两张面孔的相似度
封装YYFaceViewController
.h文件

//
//  YYFaceViewController.h
//  Demo_Face++
//
//  Created by yyMae on 15/12/25.
//  Copyright (c) 2015年 yyMae. All rights reserved.
//
#import <UIKit/UIKit.h>

@interface YYFaceViewController : UIViewController<UINavigationControllerDelegate,UIImagePickerControllerDelegate>

@end

.m文件

//
//  YYFaceViewController.m
//  Demo_Face++
//
//  Created by yyMae on 15/12/25.
//  Copyright (c) 2015年 yyMae. All rights reserved.
//

#import "YYFaceViewController.h"
#import "FaceppAPI.h"

#define kwidth self.view.frame.size.width
#define height self.view.frame.size.height
#define btnBorder 40
#define imgBorder 20

@interface YYFaceViewController ()

//显示图片的imageView
@property (nonatomic,strong) UIImageView *firstImgV;
@property (nonatomic,strong) UIImageView *secondImgV;
//触发比较相似度的button
@property (nonatomic,strong) UIButton *recognizedBtn;
//五官的相似度
@property (nonatomic,strong) NSString *eye;
@property (nonatomic,strong) NSString *eyebrow;
@property (nonatomic,strong) NSString *mouth;
@property (nonatomic,strong) NSString *nose;
@property (nonatomic,strong) NSString *similarity;
@property (nonatomic,strong) UITextView *similarityView;
//通过此标记判断选择图片要显示到哪一个相框上
@property (nonatomic,assign) NSInteger imageTag;

@end

@implementation YYFaceViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    [self drawView];
}

- (void)drawView{
    //创建两个按钮,点击事件为选择照片
    UIButton *firstBtn = [UIButton buttonWithType:UIButtonTypeSystem];
    firstBtn.frame = CGRectMake(btnBorder, 100, (kwidth - btnBorder * 3)/2, 30);
    [firstBtn setTitle:@"setFirstPhoto" forState:UIControlStateNormal];
    [firstBtn addTarget:self action:@selector(selectFirstPhoto) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:firstBtn];
    
    UIButton *secondBtn = [UIButton buttonWithType:UIButtonTypeSystem];
    secondBtn.frame = CGRectMake(CGRectGetMaxX(firstBtn.frame) + btnBorder, 100, (kwidth - btnBorder * 3)/2, 30);
    [secondBtn setTitle:@"setSecondPhoto" forState:UIControlStateNormal];
    [secondBtn addTarget:self action:@selector(selectSecondPhoto) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:secondBtn];
    
    //创建两个相框,显示图片
    UIImageView *firstImgV = [[UIImageView alloc]initWithFrame:CGRectMake(imgBorder, 140, (kwidth - imgBorder *3)/2, (kwidth - imgBorder *3)/2 *height / kwidth)];
    firstImgV.backgroundColor = [UIColor yellowColor];
    [self.view addSubview:firstImgV];
    self.firstImgV = firstImgV;
    
    UIImageView *secondImgV = [[UIImageView alloc]initWithFrame:CGRectMake(CGRectGetMaxX(firstImgV.frame) + imgBorder, 140, (kwidth - imgBorder *3)/2, (kwidth - imgBorder *3)/2 *height / kwidth)];
    secondImgV.backgroundColor = [UIColor yellowColor];
    [self.view addSubview:secondImgV];
    self.secondImgV = secondImgV;
    
    //相似度监测按钮
    UIButton *recognizedBtn = [UIButton buttonWithType:UIButtonTypeSystem];
    recognizedBtn.frame = CGRectMake(self.view.bounds.size.width / 2, CGRectGetMaxY(secondImgV.frame) + 20, (kwidth - btnBorder * 3)/2, 30);
    recognizedBtn.center = CGPointMake(self.view.bounds.size.width / 2, CGRectGetMaxY(secondImgV.frame) + 20);
    [recognizedBtn setTitle:@"相似度计算(%)" forState:UIControlStateNormal];
    [recognizedBtn addTarget:self action:@selector(recognized) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:recognizedBtn];
    recognizedBtn.enabled = NO;
    self.recognizedBtn = recognizedBtn;
    
    //添加输入框显示输出信息
    UITextView *similarityView = [[UITextView alloc]initWithFrame:CGRectMake((kwidth - 300) / 2, CGRectGetMaxY(recognizedBtn.frame) + 10, 300, 150)];
    similarityView.backgroundColor = [UIColor yellowColor];
    [self.view addSubview:similarityView];
    self.similarityView = similarityView;
    
    
}

//设置第一张图片
- (void)selectFirstPhoto{
    self.imageTag = 999;
    [self alertController];
}
//设置第二张图片
- (void)selectSecondPhoto{
    self.imageTag = 888;
    [self alertController];
}

//相似度监测
- (void)recognized{
    //获取到两张面孔的face_id
    NSString *firstFace_id;

    NSData *firstImgVData = UIImageJPEGRepresentation(self.firstImgV.image, 0.6);
    FaceppResult *firstResult = [[FaceppAPI detection] detectWithURL:nil orImageData:firstImgVData];
    NSArray *array1 = firstResult.content[@"face"];
    
    if (array1.count == 1) {
        firstFace_id = [firstResult content][@"face"][0][@"face_id"];
    }else{
        UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"提示" message:@"未检测到五官" delegate:self cancelButtonTitle:@"重新选择图片" otherButtonTitles: nil];
        [alert show];

        return;
    }

    
    NSString *secondFace_id;
    NSData *secondImgVData = UIImageJPEGRepresentation(self.secondImgV.image, 0.6);
    FaceppResult *secondResult = [[FaceppAPI detection] detectWithURL:nil orImageData:secondImgVData];
    NSArray *array2 = secondResult.content[@"face"];
    if (array2.count == 1) {
        secondFace_id = [secondResult content][@"face"][0][@"face_id"];
    }else{
        UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"提示" message:@"未检测到五官" delegate:self cancelButtonTitle:@"重新选择图片" otherButtonTitles: nil];
        [alert show];
        return;

    }
    
    //比较二者的相似度
    FaceppResult *similarResult = [[FaceppAPI recognition] compareWithFaceId1:firstFace_id andId2:secondFace_id async:NO];
    if ([similarResult success]) {
        self.eye = [similarResult content][@"component_similarity"][@"eye"];
        self.eyebrow = [similarResult content][@"component_similarity"][@"eyebrow"];
        self.mouth = [similarResult content][@"component_similarity"][@"mouth"];
        self.nose = [similarResult content][@"component_similarity"][@"nose"];
        self.similarity = [similarResult content][@"similarity"];
        
        
        NSString *content = [NSString stringWithFormat:@"眼睛:%@\n眉毛:%@\n嘴巴:%@\n鼻子:%@\n综合:%@",self.eye,self.eyebrow,self.mouth,self.nose,self.similarity];
        self.similarityView.text = content;
    }else{
        UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"提示" message:@"未检测到五官" delegate:self cancelButtonTitle:@"error" otherButtonTitles: nil];
        [alert show];

        return;
    }
    
    

}

- (void)alertController{
    UIAlertController * alertController = [UIAlertController alertControllerWithTitle:nil message:nil preferredStyle:UIAlertControllerStyleActionSheet];
    //添加Button
    [alertController addAction: [UIAlertAction actionWithTitle: @"拍照" style: UIAlertActionStyleDefault handler:^(UIAlertAction *action) {
        //处理点击拍照
        if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
            // 跳转到相机或相册页面
            UIImagePickerController *imagePickerController = [[UIImagePickerController alloc] init];
            imagePickerController.delegate = self;
            imagePickerController.allowsEditing = YES;
            [self presentViewController:imagePickerController animated:YES completion:^{}];
        }else{
            UIAlertView *alert = [[UIAlertView alloc]initWithTitle:nil message:@"打开相机失败" delegate:self cancelButtonTitle:@"取消" otherButtonTitles: nil];
            [alert show];
        }
        
    }]];
    [alertController addAction: [UIAlertAction actionWithTitle: @"从相册选取" style: UIAlertActionStyleDefault handler:^(UIAlertAction *action){
        //处理点击从相册选取
        if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary]) {
            // 跳转到相机或相册页面
            UIImagePickerController *imagePickerController = [[UIImagePickerController alloc] init];
            
            imagePickerController.delegate = self;
            
            imagePickerController.allowsEditing = YES;
            
            
            [self presentViewController:imagePickerController animated:YES completion:^{}];
        }else{
            UIAlertView *alert = [[UIAlertView alloc]initWithTitle:nil message:@"打开相机失败" delegate:self cancelButtonTitle:@"取消" otherButtonTitles: nil];
            [alert show];
        }
    }]];
    [alertController addAction: [UIAlertAction actionWithTitle: @"取消" style: UIAlertActionStyleCancel handler:nil]];
    [self presentViewController:alertController animated:YES completion:nil];
}

-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{
    [picker dismissViewControllerAnimated:YES completion:nil];
    UIImage *image = [info objectForKey:UIImagePickerControllerOriginalImage];
    if (self.imageTag == 999) {
        self.firstImgV.image = image;
    }
    if (self.imageTag == 888) {
        self.secondImgV.image = image;
    }
    if (self.firstImgV.image && self.secondImgV.image) {
        self.recognizedBtn.enabled = YES;
    }
   
}

-(void)imagePickerControllerDidCancel:(UIImagePickerController *)picker{
    [self dismissViewControllerAnimated:YES completion:nil];
}

-(void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated{

    
}

@end

效果见下图: