Recognize.js

Node.js image detection and recognition framework

Installation

First download and install GraphicsMagick. In Mac OS X, you can simply use Homebrew and do:

brew install graphicsmagick

Then download the Recognizejs using npm:

npm i recognizejs

Getting started

Import Recognizejs into your project:

const Recognizejs = require('recognizejs');

Try Recognizejs

1. Create a model with Recognizejs and initialize it:

const myModel = new Recognizejs();
 
// initialize it
// The init function returns a Promise object
await myModel.init();

PS: Model initialization may take up to 1-2 minutes (depending on the performance of your device), so please be patient. 😉

1. Read your image file

const fs = require('fs');
 
const myImgBuffer = fs.readFileSync(myImagePath);

1. Call the model's recognize function and pass the image buffer as a parameter:

// The recognize function will return a Promise object, we recommend that you use await statement to get the return value.
const results = await myModel.recognize(myImgBuffer);
 
/*
    [
        {
            className: ['className1', 'className2', 'className...'],
            probability: 0.9
        },
        {
            className: ['className1', 'className2', 'className...'],
            probability: 0.599
        }
    ]
*/
console.log(results);

The code for this example can be found in the examples folder.

API

Create a Recognizejs model object

new Recognizejs(config?);

Args: config is an optional parameter and has the following attributes:

{
    cocoSsd?: {
        // base: Controls the base cnn model, can be 'mobilenet_v1', 'mobilenet_v2' or 'lite_mobilenet_v2'. Defaults to 'lite_mobilenet_v2'. lite_mobilenet_v2 is smallest in size, and fastest in inference speed. mobilenet_v2 has the highest classification accuracy.
        base?: ObjectDetectionBaseModel,
 
        // An optional string that specifies custom url of the model. This is useful for area/countries that don't have access to the model hosted on GCP.
        modelUrl?: string
    },
    mobileNet?: {
        // The MobileNet version number. Use 1 for MobileNetV1, and 2 for MobileNetV2. Defaults to 1.
        version: 1,
 
        // Controls the width of the network, trading accuracy for performance. A smaller alpha decreases accuracy and increases performance. 0.25 is only available for V1. Defaults to 1.0.
        alpha?: 0.25 | .50 | .75 | 1.0,
 
        // Optional param for specifying the custom model url or tf.io.IOHandler object. Returns a model object.
        // If you are in mainland China, please change modelUrl to the link of the model on https://hub.tensorflow.google.cn
        modelUrl?: string
 
        // Optional param specifying the pixel value range expected by the trained model hosted at the modelUrl. This is typically [0, 1] or [-1, 1].
        inputRange?: [number, number]
    }
}

cocoSsd and mobileNet are different neural networks. cocoSsd is used to identify and classify multiple objects in an image, while mobileNet is used to accurately identify an object.

Initialize the training model

model.init(modelType?);

The init function returns a Promise object, you can use await statement to handle it.

Args: modelType can be a string or an array. You can set the model to be loaded here to avoid loading the model that is not needed. [If you don't set modelType, it will load both cocoSsd and mobileNet models]

Example:

model.init();
 
// or
 
model.init(['cocoSsd', 'mobileNet']);
 
// or
 
model.init('cocoSsd');
 
// or
 
model.init('mobileNet');

If you don't use the init function to load the model, the model will load automatically when you need to use them, but it may take a long time to load the model, so please choose the loading method as appropriate.

Identify objects in image

model.recognize(buf);

The recognize function returns a Promise object, you can use await statement to get its return value.

Args: The buf parameter requires you to pass a buffer type of image data. You can read the image through the fs module.

Return value:

[
    {
        className: [
            'giant panda',
            'panda',
            'panda bear',
            'coon bear',
            'Ailuropoda melanoleuca'
        ],
        probability: 0.9819085597991943
    },
    {
        className: [ 'Chihuahua' ],
        probability: 0.006128392647951841
    },
    {
        className: [ 'French bulldog' ],
        probability: 0.0026271280366927385
    }
]

Example:

const myImgBuf = require('fs').readFileSync(myImgPath);
 
model.recognize(myImgBuf);

Detect all objects in the image

model.detect(buf)

The detect function returns a Promise object, you can use await statement to get its return value.

Args: The buf parameter requires you to pass a buffer type of image data. You can read the image through the fs module.

Return value:

[
    {
        bbox: {
            x: 66.92952662706375,
        y: 158.30181241035461,
        width: 157.67111629247665,
        height: 165.00252485275269
        },
        class: 'bear',
        score: 0.9642460346221924
    },
    {
      bbox: {
          x: 180.56899309158325,
          y: -0.32786130905151367,
        width: 246.6680407524109,
        height: 308.3251893520355
        },
        class: 'bear',
        score: 0.9133073091506958
    }
]

Example:

const myImgBuf = require('fs').readFileSync(myImgPath);
 
model.detect(myImgBuf);

Detect all objects in the image and identify them

model.detectAndRecognize(buf);

The detectAndRecognize function returns a Promise object, you can use await statement to get its return value.

Args: The buf parameter requires you to pass a buffer type of image data. You can read the image through the fs module.

Return value:

[
    recognizeObject,
    recognizeObject,
    recognizeObject
]

Example:

const myImgBuf = require('fs').readFileSync(myImgPath);
 
model.detectAndRecognize(myImgBuf);

License

MIT

Copyright ©️ 2020, Yingxuan (Bill) Dong