Capacitor ML Kit GenAI Image Description Plugin

Unofficial Capacitor plugin for ML Kit GenAI Image Description.[^1]

[!WARNING] The ML Kit GenAI APIs are currently in beta. The API surface and behavior may change in future releases.

Use Cases

The GenAI Image Description plugin is typically used to generate a natural-language description of an image on-device using Gemini Nano, for example:

• Accessibility: Generate alternative text for images to support screen readers.
• Content moderation: Get a textual summary of user-uploaded images.
• Search and organization: Describe images to make them searchable or to auto-tag a photo library.

Requirements

This plugin uses Gemini Nano, which runs entirely on-device. It is only available on Android and has the following device requirements:

• The device must support Gemini Nano (see supported devices).
• The device must run Android API level 26 or higher.
• The device must not have an unlocked bootloader.

Use the checkFeatureStatus(...) method to check whether the feature is available on the device.

Compatibility

| Plugin Version | Capacitor Version | Status | | -------------- | ----------------- | -------------- | | 8.x.x | >=8.x.x | Active support |

Installation

You can use our AI-Assisted Setup to install the plugin. Add the Capawesome Skills to your AI tool using the following command:

npx skills add capawesome-team/skills --skill capacitor-plugins

Then use the following prompt:

Use the `capacitor-plugins` skill from `capawesome-team/skills` to install the `@capacitor-mlkit/genai-image-description` plugin in my project.

If you prefer Manual Setup, install the plugin by running the following commands and follow the platform-specific instructions below:

npm install @capacitor-mlkit/genai-image-description
npx cap sync

Android

API level

This plugin requires a minimum API level of 26. Make sure to set the minSdkVersion in your variables.gradle file to at least 26.

Variables

This plugin will use the following project variables (defined in your app’s variables.gradle file):

• $mlkitGenaiImageDescriptionVersion version of com.google.mlkit:genai-image-description (default: 1.0.0-beta1)

Usage

The following example shows how to check the feature status, download the feature and describe an image.

The image description is currently only available in English.

Check the feature status

Before using the image description feature, check whether it is available on the device:

import {
  FeatureStatus,
  GenAiImageDescription,
} from '@capacitor-mlkit/genai-image-description';

const checkFeatureStatus = async () => {
  const { featureStatus } = await GenAiImageDescription.checkFeatureStatus();
  return featureStatus === FeatureStatus.Available;
};

Download the feature

If the feature status is DOWNLOADABLE, download the feature before using it. Add a listener for the downloadProgress event to get notified about the download progress:

import { GenAiImageDescription } from '@capacitor-mlkit/genai-image-description';

const downloadFeature = async () => {
  await GenAiImageDescription.addListener('downloadProgress', event => {
    console.log('Total bytes downloaded:', event.totalBytesDownloaded);
  });
  await GenAiImageDescription.downloadFeature();
};

Describe an image

Pass the local file path of the image to describeImage(...) to generate a description. Add a listener for the inferenceProgress event to receive partial results as they are generated:

import { GenAiImageDescription } from '@capacitor-mlkit/genai-image-description';

const describeImage = async () => {
  await GenAiImageDescription.addListener('inferenceProgress', event => {
    console.log('Partial result:', event.text);
  });
  const { description } = await GenAiImageDescription.describeImage({
    path: 'file:///path/to/image.jpg',
  });
  return description;
};

API

• checkFeatureStatus()
• describeImage(...)
• downloadFeature()
• addListener('downloadProgress', ...)
• addListener('inferenceProgress', ...)
• removeAllListeners()
• Interfaces
• Enums

checkFeatureStatus()

checkFeatureStatus() => Promise<CheckFeatureStatusResult>

Check the current availability status of the image description feature.

If the status is DOWNLOADABLE, you can download the feature using downloadFeature(...).

Only available on Android.

Returns: Promise<CheckFeatureStatusResult>

Since: 8.2.0

describeImage(...)

describeImage(options: DescribeImageOptions) => Promise<DescribeImageResult>

Generate a natural-language description of the given image.

The inferenceProgress event listener will notify you about partial results as they are generated. The returned promise resolves with the full result.

The description is currently only available in English.

Only available on Android.

| Param | Type | | ------------- | --------------------------------------------------------------------- | | options | DescribeImageOptions |

Returns: Promise<DescribeImageResult>

Since: 8.2.0

downloadFeature()

downloadFeature() => Promise<void>

Download the image description feature.

The downloadProgress event listener will notify you about the download progress. The returned promise resolves when the download is complete or the feature is already available.

Only available on Android.

Since: 8.2.0

addListener('downloadProgress', ...)

addListener(eventName: 'downloadProgress', listenerFunc: (event: DownloadProgressEvent) => void) => Promise<PluginListenerHandle>

Called while the image description feature is being downloaded.

Only available on Android.

| Param | Type | | ------------------ | ------------------------------------------------------------------------------------------- | | eventName | 'downloadProgress' | | listenerFunc | (event: DownloadProgressEvent) => void |

Returns: Promise<PluginListenerHandle>

Since: 8.2.0

addListener('inferenceProgress', ...)

addListener(eventName: 'inferenceProgress', listenerFunc: (event: InferenceProgressEvent) => void) => Promise<PluginListenerHandle>

Called when a new partial result is available during inference.

Only available on Android.

| Param | Type | | ------------------ | --------------------------------------------------------------------------------------------- | | eventName | 'inferenceProgress' | | listenerFunc | (event: InferenceProgressEvent) => void |

Returns: Promise<PluginListenerHandle>

Since: 8.2.0

removeAllListeners()

removeAllListeners() => Promise<void>

Remove all listeners for this plugin.

Since: 8.2.0

Interfaces

CheckFeatureStatusResult

| Prop | Type | Description | Since | | ------------------- | ------------------------------------------------------- | ----------------------------------------------------------------- | ----- | | featureStatus | FeatureStatus | The current availability status of the image description feature. | 8.2.0 |

DescribeImageResult

| Prop | Type | Description | Since | | ----------------- | ------------------- | ---------------------------------------------- | ----- | | description | string | The natural-language description of the image. | 8.2.0 |

DescribeImageOptions

| Prop | Type | Description | Since | | ---------- | ------------------- | --------------------------------------------- | ----- | | path | string | The local file path of the image to describe. | 8.2.0 |

PluginListenerHandle

| Prop | Type | | ------------ | ----------------------------------------- | | remove | () => Promise<void> |

DownloadProgressEvent

| Prop | Type | Description | Since | | -------------------------- | ------------------- | -------------------------------------------- | ----- | | totalBytesDownloaded | number | The total number of bytes downloaded so far. | 8.2.0 |

InferenceProgressEvent

| Prop | Type | Description | Since | | ---------- | ------------------- | ----------------------------------- | ----- | | text | string | The new text of the partial result. | 8.2.0 |

Enums

FeatureStatus

| Members | Value | Description | Since | | ------------------ | --------------------------- | ----------------------------------------------------------- | ----- | | Available | 'AVAILABLE' | The feature is available to use. | 8.2.0 | | Downloadable | 'DOWNLOADABLE' | The feature can be downloaded using downloadFeature(...). | 8.2.0 | | Downloading | 'DOWNLOADING' | The feature is currently being downloaded. | 8.2.0 | | Unavailable | 'UNAVAILABLE' | The feature is not available on this device. | 8.2.0 |

FAQ

What are the requirements to use this plugin?

The image description is performed on-device by Gemini Nano. This requires a device that supports Gemini Nano, Android API level 26 or higher and a locked bootloader (see Requirements). Use the checkFeatureStatus(...) method to check whether the feature is available on the device.

Why is this plugin only available on Android?

The ML Kit GenAI APIs are based on Gemini Nano and AICore, which are currently only available on Android. On iOS and Web, all methods reject with an appropriate error.

In which language is the description generated?

The image description is currently only available in English. Support for more languages is planned for future releases.

How do I get the description as a stream?

Add a listener for the inferenceProgress event before calling describeImage(...). The listener is called with each partial result as it is generated. The promise returned by describeImage(...) resolves with the full result.

Can I use this plugin with Ionic, React, Vue or Angular?

Yes, the plugin is framework-agnostic. It works in any Capacitor app regardless of the web framework, including Ionic with Angular, React, or Vue, as well as plain JavaScript projects.

Related Plugins

• Translation: Unofficial Capacitor plugin for ML Kit Translation.
• Smart Reply: Unofficial Capacitor plugin for ML Kit Smart Reply.
• GenAI Prompt: Run custom GenAI prompts, for example to expand on a generated image description.

Terms & Privacy

This plugin uses the Google ML Kit:

• Terms & Privacy
• Android Data Disclosure
• iOS Data Disclosure

Newsletter

Stay up to date with the latest news and updates about the Capawesome, Capacitor, and Ionic ecosystem by subscribing to our Capawesome Newsletter.

Changelog

See CHANGELOG.md.

License

See LICENSE.

[^1]: This project is not affiliated with, endorsed by, sponsored by, or approved by Google LLC or any of their affiliates or subsidiaries.