# 人脸比对

## 适用场景

输入的两张比对图片是同一个人的照片时，系统返回的比对结果为"同一个人"，置信分数比较高；当两张比对图片不是同一个人的照片时，系统返回的比对结果为"非同一个人"，置信分数很低。该功能可用于人脸比对的场景，例如身份验证、人脸解锁等安全相关场景。

效果如下图所示：

![](https://contentcenter-vali-drcn.dbankcdn.cn/pvt_2/DeveloperAlliance_scene_100_1/de/v3/xTcLid0WR8GYvqmmPHvO4g/zh-cn_image_0000002794491645.png?HW-CC-KV=V1&HW-CC-Date=20261015T104512Z&HW-CC-Expire=31536000000&HW-CC-Sign=9FC29550C274BBBB516F9C79513ABD9EAB20C9702A6ED6E2659921A73B38F377)

## 开发步骤

1. 在使用人脸比对时，将实现人脸比对相关的类添加至工程。

   ```typescript
   import { faceComparator } from '@kit.CoreVisionKit';
   import { image } from '@kit.ImageKit';
   import { hilog } from '@kit.PerformanceAnalysisKit';
   import { BusinessError } from '@kit.BasicServicesKit';
   import { fileIo } from '@kit.CoreFileKit';
   import { photoAccessHelper } from '@kit.MediaLibraryKit';
   ```

2. 初始化和释放：在aboutToAppear中调用[faceComparator.init()](https://developer.huawei.com/consumer/cn/doc/harmonyos-references/core-vision-facecomparator-api#facecomparatorinit)初始化人脸比对分析器（加载模型），在aboutToDisappear中调用[faceComparator.release()](https://developer.huawei.com/consumer/cn/doc/harmonyos-references/core-vision-facecomparator-api#facecomparatorrelease)释放资源。

   ```typescript
   async aboutToAppear(): Promise<void> {
     const initResult = await faceComparator.init();
     hilog.info(0x0000, TAG, `Face comparator initialization result:${initResult}`);
   }

   async aboutToDisappear(): Promise<void> {
     await faceComparator.release();
     hilog.info(0x0000, TAG, 'Face comparator released successfully');
   }
   ```

3. 通过photoAccessHelper.PhotoViewPicker拉起图库选择两张待比对的图片，使用fileIo与image模块将URI转换为[PixelMap](https://developer.huawei.com/consumer/cn/doc/harmonyos-references/arkts-apis-image-pixelmap)，为后续比对接口准备输入数据。

   ```typescript
   Button('选择图片')
     .type(ButtonType.Capsule)
     .fontColor(Color.White)
     .alignSelf(ItemAlign.Center)
     .width('80%')
     .margin(10)
     .onClick(() => {
       // 拉起图库，获取图片资源
       void this.selectImage();
     })
   ```

   选择图片与解码图片的方法实现如下：

   ```typescript
   private async selectImage() {
     let uri = await this.openPhoto();
     if (uri === undefined) {
       hilog.error(0x0000, TAG, 'Failed to get two image uris.');
       return;
     }
     this.loadImage(uri);
   }

   private async openPhoto(): Promise<string[]> {
     return new Promise<string[]>((resolve, reject) => {
       let photoPicker: photoAccessHelper.PhotoViewPicker = new photoAccessHelper.PhotoViewPicker();
       photoPicker.select({
         MIMEType: photoAccessHelper.PhotoViewMIMETypes.IMAGE_TYPE,
         maxSelectNumber: 2
       }).then(res => {
         resolve(res.photoUris);
       }).catch((err: BusinessError) => {
         hilog.error(0x0000, TAG, `Failed to get photo image uris. code: ${err.code}, message: ${err.message}`);
         reject();
       });
     });
   }

   private loadImage(names: string[]) {
     setTimeout(async () => {
       let imageSource: image.ImageSource | undefined = undefined;
       let fileSource: fileIo.File;
       fileSource = await fileIo.open(names[0], fileIo.OpenMode.READ_ONLY);
       imageSource = image.createImageSource(fileSource.fd);
       this.chooseImage = await imageSource.createPixelMap();
       fileSource = await fileIo.open(names[1], fileIo.OpenMode.READ_ONLY);
       imageSource = image.createImageSource(fileSource.fd);
       this.chooseImage1 = await imageSource.createPixelMap();
       await fileIo.close(fileSource);
     }, 100);
   }
   ```

4. 构造[VisionInfo](https://developer.huawei.com/consumer/cn/doc/harmonyos-references/core-vision-facecomparator-api#visioninfo)对象并传入两张图片的PixelMap，调用[faceComparator.compareFaces](https://developer.huawei.com/consumer/cn/doc/harmonyos-references/core-vision-facecomparator-api#facecomparatorcomparefaces)方法，获取相似度分数，并将结果展示在界面上。

   ```typescript
   Button('人脸比对')
     .type(ButtonType.Capsule)
     .fontColor(Color.White)
     .alignSelf(ItemAlign.Center)
     .width('80%')
     .margin(10)
     .onClick(() => {
       if (!this.chooseImage || !this.chooseImage1) {
         hilog.error(0x0000, TAG, 'Failed to choose image');
         return;
       }
       // 调用人脸比对接口
       let visionInfo: faceComparator.VisionInfo = {
         pixelMap: this.chooseImage
       };
       let visionInfo1: faceComparator.VisionInfo = {
         pixelMap: this.chooseImage1
       };
        faceComparator.compareFaces(visionInfo, visionInfo1)
        .then((data: faceComparator.FaceCompareResult) => {
          if (data !== undefined) {
            let faceString = `degree of similarity: ${this.toPercentage(data.similarity)}${(data.isSamePerson) ? '. is' : '. no'} same person`;
            hilog.info(0x0000, TAG, 'faceString data is ' + faceString);
            this.dataValues = faceString;
          } else {
            hilog.error(0x0000, TAG, 'Invalid data received from face comparison');
            this.dataValues = 'Error: Invalid data';
          }
        })
        .catch((error: BusinessError) => {
          hilog.error(0x0000, TAG, `Face comparison failed. Code: ${error.code}, message: ${error.message}`);
          this.dataValues = `Error: ${error.message}`;
        });
      })
   ```

   相似度数值转百分比展示的辅助方法：

   ```typescript
   private toPercentage(num: number): string {
     return `${(num * 100).toFixed(2)}%`;
   }
   ```

## 开发实例

### Index.ets

```typescript
import { faceComparator } from '@kit.CoreVisionKit';
import { image } from '@kit.ImageKit';
import { hilog } from '@kit.PerformanceAnalysisKit';
import { BusinessError } from '@kit.BasicServicesKit';
import { fileIo } from '@kit.CoreFileKit';
import { photoAccessHelper } from '@kit.MediaLibraryKit';

const TAG: string = 'FaceCompareSample';

@Entry
@Component
struct Index {
  @State chooseImage: PixelMap | undefined = undefined;
  @State chooseImage1: PixelMap | undefined = undefined;
  @State dataValues: string = '';

  async aboutToAppear(): Promise<void> {
    const initResult = await faceComparator.init();
    hilog.info(0x0000, TAG, `Face comparator initialization result:${initResult}`);
  }

  async aboutToDisappear(): Promise<void> {
    await faceComparator.release();
    hilog.info(0x0000, TAG, 'Face comparator released successfully');
  }

  build() {
    Column() {
      Image(this.chooseImage)
        .objectFit(ImageFit.Fill)
        .height('30%')
        .accessibilityDescription('默认图片1')
      Image(this.chooseImage1)
        .objectFit(ImageFit.Fill)
        .height('30%')
        .accessibilityDescription('默认图片2')
      Text(this.dataValues)
        .copyOption(CopyOptions.LocalDevice)
        .height('15%')
        .margin(10)
        .width('60%')
      Button('选择图片')
        .type(ButtonType.Capsule)
        .fontColor(Color.White)
        .alignSelf(ItemAlign.Center)
        .width('80%')
        .margin(10)
        .onClick(() => {
          // 拉起图库
          void this.selectImage();
        })
      Button('人脸比对')
        .type(ButtonType.Capsule)
        .fontColor(Color.White)
        .alignSelf(ItemAlign.Center)
        .width('80%')
        .margin(10)
        .onClick(() => {
          if (!this.chooseImage || !this.chooseImage1) {
            hilog.error(0x0000, TAG, 'Failed to choose image');
            return;
          }
          // 调用人脸比对接口
          let visionInfo: faceComparator.VisionInfo = {
            pixelMap: this.chooseImage
          };
          let visionInfo1: faceComparator.VisionInfo = {
            pixelMap: this.chooseImage1
          };
          faceComparator.compareFaces(visionInfo, visionInfo1)
            .then((data: faceComparator.FaceCompareResult) => {
              if (data !== undefined) {
                let faceString = `degree of similarity: ${this.toPercentage(data.similarity)}${(data.isSamePerson) ? '. is' : '. no'} same person`;
                hilog.info(0x0000, TAG, 'faceString data is ' + faceString);
                this.dataValues = faceString;
              } else {
                hilog.error(0x0000, TAG, 'Invalid data received from face comparison');
                this.dataValues = 'Error: Invalid data';
              }
            })
            .catch((error: BusinessError) => {
              hilog.error(0x0000, TAG, `Face comparison failed. Code: ${error.code}, message: ${error.message}`);
              this.dataValues = `Error: ${error.message}`;
            });
        })
    }
    .width('100%')
    .height('100%')
    .justifyContent(FlexAlign.Center)
  }

  private toPercentage(num: number): string {
    return `${(num * 100).toFixed(2)}%`;
  }

  private async selectImage() {
    let uris: string[] = await this.openPhoto();
    if (uris === undefined || uris.length < 2) {
      hilog.error(0x0000, TAG, 'Failed to get two image uris.');
      return;
    }
    this.loadImage(uris);
  }

  private async openPhoto(): Promise<string[]> {
    return new Promise<string[]>((resolve, reject) => {
      let photoPicker: photoAccessHelper.PhotoViewPicker = new photoAccessHelper.PhotoViewPicker();
      photoPicker.select({
        MIMEType: photoAccessHelper.PhotoViewMIMETypes.IMAGE_TYPE,
        maxSelectNumber: 2
      }).then(res => {
        resolve(res.photoUris);
      }).catch((err: BusinessError) => {
        hilog.error(0x0000, TAG, `Failed to get photo image uris. code: ${err.code}, message: ${err.message}`);
        reject();
      });
    });
  }

  private loadImage(names: string[]) {
    setTimeout(async () => {
      let imageSource: image.ImageSource | undefined = undefined;
      let fileSource: fileIo.File;
      fileSource = await fileIo.open(names[0], fileIo.OpenMode.READ_ONLY);
      imageSource = image.createImageSource(fileSource.fd);
      this.chooseImage = await imageSource.createPixelMap();
      fileSource = await fileIo.open(names[1], fileIo.OpenMode.READ_ONLY);
      imageSource = image.createImageSource(fileSource.fd);
      this.chooseImage1 = await imageSource.createPixelMap();
      await fileIo.close(fileSource);
    }, 100);
  }
}
```