Implementing TensorFlowjs model in Ionic framework with Capacitor - ionic-framework

Question

I am working on a project where I am using Ionic and TensorFlow for machine learning. I have converted my TensorFlow model to a tensorflowjs model. I have put the model.json file and shard files of the tensorflowjs model in the assets folder in Ionic. Basically, I have put my tensorflowjs model in the assets folder of ionic. I am wanting to use Capacitor to access the camera and allow users to take photos. Then, the photos will be passed to the tensorflowjs model in assets to get and display a prediction for that user.
Here is my typescript code:
import { Component, OnInit, ViewChild, ElementRef, Renderer2 } from '#angular/core';
import { Plugins, CameraResultType, CameraSource} from '#capacitor/core';
import { DomSanitizer, SafeResourceUrl} from '#angular/platform-browser';
import { Platform } from '#ionic/angular';
import * as tf from '#tensorflow/tfjs';
import { rendererTypeName } from '#angular/compiler';
import { Base64 } from '#ionic-native/base64/ngx';
import { defineCustomElements } from '#ionic/pwa-elements/loader';
const { Camera } = Plugins;
#Component({
  selector: 'app-predict',
  templateUrl: './predict.page.html',
  styleUrls: ['./predict.page.scss'],
})
export class PredictPage{
  linearModel : tf.Sequential;
  prediction : any;
  InputTaken : any;
  ctx: CanvasRenderingContext2D;
  pos = { x: 0, y: 0 };
  canvasElement : any;
  photo: SafeResourceUrl;
  model: tf.LayersModel;
  constructor(public el : ElementRef , public renderer : Renderer2 , public platform : Platform, private base64: Base64,
    private sanitizer: DomSanitizer) 
  {}
  
  async takePicture() {
    const image = await Camera.getPhoto({
        quality: 90,
        allowEditing: true,
        resultType: CameraResultType.DataUrl,
        source: CameraSource.Camera});
      const model = await tf.loadLayersModel('src/app/assets/model.json');
      this.photo = this.sanitizer.bypassSecurityTrustResourceUrl(image.base64String);
      defineCustomElements(window);
    const pred = await tf.tidy(() => {
          // Make and format the predications
        const output = this.model.predict((this.photo)) as any;
                                
          // Save predictions on the component
        this.prediction = Array.from(output.dataSync()); 
        });
  }
}
In this code, I have imported the necessary tools. Then, I have my constructor function and a takepicture() function. In the takepicture function, I have included functionality for the user to take pictures. However, I am having trouble with passing the pictures taken to the tensorflowjs model to get a prediction. I am passing the picture taken to the tensorflowjs model in this line of code:
const output = this.model.predict((this.photo)) as any;
However, I am getting an error stating that:
Argument of type 'SafeResourceUrl' is not assignable to parameter of type 'Tensor | Tensor[]'.\n Type 'SafeResourceUrl' is missing the following properties from type 'Tensor[]': length, pop, push, concat, and 26 more.
It would be appreciated if I could receive some guidance regarding this topic.

Answer 1

The model is expecting you to pass in a Tensor input, but you're passing it some other image format that isn't in the tfjs ecosystem. You should first convert this.photo to a Tensor, or perhaps easier, convert image.base64String to tensor.
Since you seem to be using node, try this code
// Move the base64 image into a buffer
const b = Buffer.from(image.base64String, 'base64')
// get the tensor
const image = tf.node.decodeImage(b)
// Compute the output
const output = this.model.predict(image) as any;
Other conversion solutions here: convert base64 image to tensor