face-api/src/faceFeatureExtractor/FaceFeatureExtractor.ts

import * as tf from '../../dist/tfjs.esm';

import { NetInput, TNetInput, toNetInput } from '../dom/index';
import { NeuralNetwork } from '../NeuralNetwork';
import { normalize } from '../ops/index';
import { denseBlock4 } from './denseBlock';
import { extractParams } from './extractParams';
import { extractParamsFromWeightMap } from './extractParamsFromWeightMap';
import { FaceFeatureExtractorParams, IFaceFeatureExtractor } from './types';

export class FaceFeatureExtractor extends NeuralNetwork<FaceFeatureExtractorParams> implements IFaceFeatureExtractor<FaceFeatureExtractorParams> {
  constructor() {
    super('FaceFeatureExtractor');
  }

  public forwardInput(input: NetInput): tf.Tensor4D {
    const { params } = this;

    if (!params) {
      throw new Error('FaceFeatureExtractor - load model before inference');
    }

    return tf.tidy(() => {
      const batchTensor = tf.cast(input.toBatchTensor(112, true), 'float32');
      const meanRgb = [122.782, 117.001, 104.298];
      const normalized = normalize(batchTensor, meanRgb).div(tf.scalar(255)) as tf.Tensor4D;

      let out = denseBlock4(normalized, params.dense0, true);
      out = denseBlock4(out, params.dense1);
      out = denseBlock4(out, params.dense2);
      out = denseBlock4(out, params.dense3);
      out = tf.avgPool(out, [7, 7], [2, 2], 'valid');

      return out;
    });
  }

  public async forward(input: TNetInput): Promise<tf.Tensor4D> {
    return this.forwardInput(await toNetInput(input));
  }

  protected getDefaultModelName(): string {
    return 'face_feature_extractor_model';
  }

  protected extractParamsFromWeightMap(weightMap: tf.NamedTensorMap) {
    return extractParamsFromWeightMap(weightMap);
  }

  protected extractParams(weights: Float32Array) {
    return extractParams(weights);
  }
}