@vladmandic/face-api/src/ssdMobilenetv1/mobileNetV1.ts

FaceAPI: AI-powered Face Detection & Rotation Tracking, Face Description & Recognition, Age & Gender & Emotion Prediction for Browser and NodeJS using TensorFlow/JS

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

import { pointwiseConvLayer } from './pointwiseConvLayer';
import { MobileNetV1 } from './types';

const epsilon = 0.0010000000474974513;

function depthwiseConvLayer(x: tf.Tensor4D, params: MobileNetV1.DepthwiseConvParams, strides: [number, number]) {
  return tf.tidy(() => {
    let out = tf.depthwiseConv2d(x, params.filters, strides, 'same');
    out = tf.batchNorm<tf.Rank.R4>(
      out,
      params.batch_norm_mean,
      params.batch_norm_variance,
      params.batch_norm_offset,
      params.batch_norm_scale,
      epsilon,
    );
    return tf.clipByValue(out, 0, 6);
  });
}

function getStridesForLayerIdx(layerIdx: number): [number, number] {
  return [2, 4, 6, 12].some((idx) => idx === layerIdx) ? [2, 2] : [1, 1];
}

export function mobileNetV1(x: tf.Tensor4D, params: MobileNetV1.Params) {
  return tf.tidy(() => {
    let conv11;
    let out = pointwiseConvLayer(x, params.conv_0, [2, 2]);

    const convPairParams = [
      params.conv_1,
      params.conv_2,
      params.conv_3,
      params.conv_4,
      params.conv_5,
      params.conv_6,
      params.conv_7,
      params.conv_8,
      params.conv_9,
      params.conv_10,
      params.conv_11,
      params.conv_12,
      params.conv_13,
    ];

    convPairParams.forEach((param, i) => {
      const layerIdx = i + 1;
      const depthwiseConvStrides = getStridesForLayerIdx(layerIdx);
      out = depthwiseConvLayer(out, param.depthwise_conv, depthwiseConvStrides);
      out = pointwiseConvLayer(out, param.pointwise_conv, [1, 1]);
      if (layerIdx === 11) conv11 = out;
    });

    if (conv11 === null) {
      throw new Error('mobileNetV1 - output of conv layer 11 is null');
    }

    return {
      out,
      conv11: conv11 as any,
    };
  });
}