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Object Storage Service:Image quality assessment

Last Updated:Feb 05, 2025

The image quality assessment feature assesses the visual quality of an image based on a set of metrics, such as the resolution, noise, distortion, color saturation, and exposure. Image quality assessment provides an overall score that indicates the image quality. Image quality assessment can be used to select a high-quality cover image for articles and a thumbnail for videos, remove duplicate images, and filter out low-quality images. This topic describes the parameters and examples of image quality assessment.

Scenarios

  • Document cover image selection: Image quality assessment helps document creators select high-quality and visually appealing cover images, which can contribute to high click-through rates and visits.

  • Video thumbnail selection: Image quality assessment helps video content creators select high-quality and visually appealing images as video thumbnails, which can contribute to high click-through rates and enhanced viewer experience.

  • Low-quality image filtering: In image processing and storage systems, low-quality images may occupy a large amount of storage space and degrade system performance and user experience. Image quality assessment can be used to automatically filter out blurry, distorted, or noisy images. You can use this feature to increase image library quality and usability.

Prerequisites

  • Intelligent Media Management (IMM) is activated. For information, see Activate IMM.

  • An Object Storage Service (OSS) bucket is associated with your Intelligent Media Management (IMM) project. For more information about how to associate an IMM project with an OSS bucket in the OSS console, see Getting started. For more information about how to associate an IMM project with a bucket by calling an API operation, see AttachOSSBucket.

Usage notes

  • Image quality assessment supports only synchronous processing (x-oss-process).

  • Anonymous access will be denied.

  • You must have the required permissions to use the feature. For more information, see permissions.

Parameters

Action: image/score

Note

For more information about the response parameters, see DetectImageScore.

Examples

Use OSS SDKs

The following sample code provides examples on how to obtain the quality score of an image by using OSS SDKs for common programming languages. If you want to obtain the quality score of an image by using SDKs for other programming languages, modify the parameters based on the following sample code.

Java

OSS SDK for Java V3.17.4 or later is required.

import com.aliyun.oss.ClientBuilderConfiguration;
import com.aliyun.oss.OSS;
import com.aliyun.oss.OSSClientBuilder;
import com.aliyun.oss.common.auth.CredentialsProviderFactory;
import com.aliyun.oss.common.auth.EnvironmentVariableCredentialsProvider;
import com.aliyun.oss.common.comm.SignVersion;
import com.aliyun.oss.model.OSSObject;
import com.aliyun.oss.model.GetObjectRequest;
import com.aliyuncs.exceptions.ClientException;

import java.io.ByteArrayOutputStream;
import java.io.IOException;

public class Demo {
    public static void main(String[] args) throws ClientException, ClientException {
        // Specify the endpoint of the region in which the bucket is located. 
        String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
        // Specify the region of the bucket in which the image is stored. Example: cn-hangzhou. 
        String region = "cn-hangzhou";
        // Obtain a credential from the environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
        EnvironmentVariableCredentialsProvider credentialsProvider = CredentialsProviderFactory.newEnvironmentVariableCredentialsProvider();
        // Specify the name of the bucket. 
        String bucketName = "examplebucket";
        // If the image is stored in the root directory of the bucket, enter the image name. If the image is not stored in the root directory of the bucket, you must specify the full path of the image. Example: exampledir/example.jpg. 
        String key = "example.jpg";

        // Create an OSSClient instance. 
        ClientBuilderConfiguration clientBuilderConfiguration = new ClientBuilderConfiguration();
        clientBuilderConfiguration.setSignatureVersion(SignVersion.V4);
        OSS ossClient = OSSClientBuilder.create()
                .endpoint(endpoint)
                .credentialsProvider(credentialsProvider)
                .clientConfiguration(clientBuilderConfiguration)
                .region(region)
                .build();

        try {
            // Create an image quality assessment instruction. 
            GetObjectRequest getObjectRequest = new GetObjectRequest(bucketName, key);
            getObjectRequest.setProcess("image/score");

            // Use the process parameter of the getObject method to pass the processing instruction. 
            OSSObject ossObject = ossClient.getObject(getObjectRequest);

            // Read and display the query results. 
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            byte[] buffer = new byte[1024];
            int bytesRead;
            while ((bytesRead = ossObject.getObjectContent().read(buffer)) != -1) {
                baos.write(buffer, 0, bytesRead);
            }
            String imageScore = baos.toString("UTF-8");
            System.out.println("Image Score:");
            System.out.println(imageScore);
        } catch (IOException e) {
            System.out.println("Error: " + e.getMessage());
        } finally {
            // Stop the OSSClient instance. 
            ossClient.shutdown();
        }
    }
}

Python

OSS SDK for Python V2.18.4 or later is required.

# -*- coding: utf-8 -*-
import oss2
from oss2.credentials import EnvironmentVariableCredentialsProvider

# Obtain a credential from the environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
auth = oss2.ProviderAuthV4(EnvironmentVariableCredentialsProvider())

# Specify the endpoint of the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the endpoint to https://oss-cn-hangzhou.aliyuncs.com. 
endpoint = 'https://oss-cn-hangzhou.aliyuncs.com'
# Specify the ID of the Alibaba Cloud region in which the bucket is located. 
region = 'cn-hangzhou'
bucket = oss2.Bucket(auth, endpoint, 'examplebucket', region=region)

# If the image is stored in the root directory of the bucket, enter the image name. If the image is not stored in the root directory of the bucket, you must specify the full path of the image. Example: exampledir/example.jpg. 
key = 'example.jpg'

# Create an image quality assessment instruction. 
process = 'image/score'

try:
    # Use the get_object method and pass the processing instruction by using the process parameter. 
    result = bucket.get_object(key, process=process)

    # Read and display the query results. 
    image_score = result.read().decode('utf-8')
    print("Image Score:")
    print(image_score)
except oss2.exceptions.OssError as e:
    print("Error:", e)

Go

OSS SDK for Go V3.0.2 or later is required.

package main

import (
	"fmt"
	"io"
	"os"

	"github.com/aliyun/aliyun-oss-go-sdk/oss"
)

func main() {
	// Obtain a temporary credential from the environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
	provider, err := oss.NewEnvironmentVariableCredentialsProvider()
	if err != nil {
		fmt.Println("Error:", err)
		os.Exit(-1)
	}
	// Create an OSSClient instance. 
	// Specify the endpoint of the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the endpoint to https://oss-cn-hangzhou.aliyuncs.com. Specify your actual endpoint. 
	// Specify the ID of the Alibaba Cloud region in which the bucket is located. Example: cn-hangzhou. 
	client, err := oss.New("https://oss-cn-hangzhou.aliyuncs.com", "", "", oss.SetCredentialsProvider(&provider), oss.AuthVersion(oss.AuthV4), oss.Region("cn-hangzhou"))
	if err != nil {
		fmt.Println("Error:", err)
		os.Exit(-1)
	}
	// Specify the name of the bucket. Example: examplebucket. 
	bucketName := "examplebucket"

	bucket, err := client.Bucket(bucketName)
	if err != nil {
		fmt.Println("Error:", err)
		os.Exit(-1)
	}
	// If the image is stored in the root directory of the bucket, enter the image name. If the image is not stored in the root directory of the bucket, you must specify the full path of the image. Example: exampledir/example.jpg. 
	// Create an image quality assessment instruction by using the oss.Process method. 
	body, err := bucket.GetObject("example.jpg", oss.Process("image/score"))
	if err != nil {
		fmt.Println("Error:", err)
		os.Exit(-1)
	}

	defer body.Close()

	data, err := io.ReadAll(body)
	if err != nil {
		fmt.Println("Error:", err)
		os.Exit(-1)
	}
	fmt.Println("data:", string(data))
}

PHP

OSS SDK for PHP V2.7.0 or later is required.

<?php
if (is_file(__DIR__ . '/../autoload.php')) {
    require_once __DIR__ . '/../autoload.php';
}
if (is_file(__DIR__ . '/../vendor/autoload.php')) {
    require_once __DIR__ . '/../vendor/autoload.php';
}
use OSS\Credentials\EnvironmentVariableCredentialsProvider;
use OSS\OssClient;

try {
    // Obtain a credential from the environment variables. Before you run the sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are configured. 
    $provider = new EnvironmentVariableCredentialsProvider(); 
    // Specify the endpoint of the region in which the bucket is located. For example, if the bucket is located in the China (Hangzhou) region, set the endpoint to https://oss-cn-hangzhou.aliyuncs.com. 
    $endpoint = 'https://oss-cn-hangzhou.aliyuncs.com';
    // Specify the name of the bucket. Example: examplebucket. 
    $bucket = 'examplebucket';
    // If the image is stored in the root directory of the bucket, enter the image name. If the image is not stored in the root directory of the bucket, you must specify the full path of the image. Example: exampledir/example.jpg. 
    $key = 'example.jpg'; 

    $config = array(
        "provider" => $provider,
        "endpoint" => $endpoint,        
        "signatureVersion" => OssClient::OSS_SIGNATURE_VERSION_V4,
        // Specify the ID of the Alibaba Cloud region in which the bucket is located. 
        "region" => "cn-hangzhou"
    );
    $ossClient = new OssClient($config);
  // Create an image quality assessment instruction. 
  $options[$ossClient::OSS_PROCESS] = "image/score";
  $result = $ossClient->getObject($bucket,$key,$options);
  var_dump($result);
} catch (OssException $e) {
  printf($e->getMessage() . "\n");
  return;
}

Use the RESTful API

If your business requires a high level of customization, you can directly call RESTful APIs. To directly call an API, you must include the signature calculation in your code. For more information about how to calculate the Authorization header, see (Recommended) Include a V4 signature in the Authorization header.

You can process images by specifying the x-oss-process parameter in the GetObject request. For more information, see GetObject.

Sample request

GET /example.jpg?x-oss-process=image/score HTTP/1.1
Host: image-demo.oss-cn-hangzhou.aliyuncs.com
Date: Fri, 21 Jul 2023 08:28:33 GMT
Authorization: SignatureValue

Sample response

HTTP/1.1 200 OK
Server: AliyunOSS
Date: Fri, 21 Jul 2023 08:28:34 GMT
Content-Type: application/json;charset=utf-8
Content-Length: 96
Connection: keep-alive
x-oss-request-id: 64BA41B2F326DB30370FEBC9
ETag: "2CE2EA370531B7CC1D23BE6015CF5DA5"
Last-Modified: Mon, 10 Jul 2023 13:07:30 GMT
x-oss-object-type: Normal
x-oss-hash-crc64ecma: 13420962247653419692
x-oss-storage-class: Standard
x-oss-ec: 0048-00000104
Content-Disposition: attachment
x-oss-force-download: true
x-oss-server-time: 466


{
  "ImageScore":
  {
    "OverallQualityScore":0.705
  },
  "RequestId":"E4B48BE7-46D9-589D-AB6D-C16E9A09A075"
}