The quality adjustment operation uses the format of a source image to compress the image. You can use quality adjustment parameters to adjust the quality of source images stored in Object Storage Service (OSS). This topic describes the parameters and examples for image quality adjustment.
Quality adjustment takes effect only on JPG and WebP images.
Parameters
Action: quality
The following table describes the parameters that you can configure to adjust the quality of a source image.
Parameter | Description | Valid value |
q | Specifies the relative quality of the image and compresses the source image based on percentage. If the source image quality is 100%, you can obtain an image whose quality is 90% after you add the Note The q parameter takes effect on only JPG images to specify the relative quality of the images. If a source image is in the WebP format, this parameter works in the same manner as the Q parameter and specifies the absolute quality of the image. | [1,100] |
Q | Specifies the absolute quality of the image.
Note The Q parameter takes effect on only JPG and WebP images. | [1,100] |
Methods
Adjust the quality of a public-read or public-read-write image
You can add image processing (IMG) parameters to the URL of a public-read or public-read write image to adjust the quality of the image.
This section provides examples on how to adjust the quality of an image named example.jpg in the oss-console-img-demo-cn-hangzhou bucket in the China (Hangzhou) region. The image is hosted at the following URL:
Adjust the relative quality of the image
Set the relative quality of the image to 80%: quality,q_80. The following URL is used to process the image based on the preceding parameter: https://oss-console-img-demo-cn-hangzhou.oss-cn-hangzhou.aliyuncs.com/example.jpg?x-oss-process=image/quality,q_80.
Adjust the absolute quality of the image
Set the absolute quality of the image to 90%: quality,Q_90. The following URL is used to process the image based on the preceding parameter: https://oss-console-img-demo-cn-hangzhou.oss-cn-hangzhou.aliyuncs.com/example.jpg?x-oss-process=image/quality,Q_90.
Adjust the quality of a private image
You can use OSS SDKs and API operations to adjust the quality of private images.
Use OSS SDKs
The following sample code provides examples on how to adjust the quality of a private image by using OSS SDKs for common programming languages. For more information about how to adjust the quality of a private image by using other programming languages, see Overview.
Java
OSS SDK for Java 3.17.4 or later is required.
import com.aliyun.oss.*;
import com.aliyun.oss.common.auth.*;
import com.aliyun.oss.common.comm.SignVersion;
import com.aliyun.oss.model.GetObjectRequest;
import java.io.File;
public class Demo {
public static void main(String[] args) throws Throwable {
// In this example, the endpoint of the China (Hangzhou) region is used. Specify your actual endpoint.
String endpoint = "https://oss-cn-hangzhou.aliyuncs.com";
// Specify the region of the bucket in which the private image is stored. Example: cn-hangzhou.
String region = "cn-hangzhou";
// Obtain access credentials from 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. Example: examplebucket.
String bucketName = "examplebucket";
// Specify the full path of the object. Do not include the bucket name in the full path.
String objectName = "example.jpg";
// Specify the full path of the local file. Example: D:\\dest.jpg. If a file that has the same name already exists in the path, the processed image overwrites the file. Otherwise, the processed image is saved in the path.
String pathName = "D:\\dest.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 {
// Set the absolute quality of the source image to 80%.
String image = "image/quality,Q_80";
GetObjectRequest request = new GetObjectRequest(bucketName, objectName);
request.setProcess(image);
// Set the name of the processed image to dest.jpg and save it to your local computer.
// If you specify only the name of the local file such as dest.jpg without specifying the local path of the file, the processed image is saved to the local path of the project to which the sample program belongs.
ossClient.getObject(request, new File("D:\\dest.jpg"));
} catch (OSSException oe) {
System.out.println("Caught an OSSException, which means your request made it to OSS, "
+ "but was rejected with an error response for some reason.");
System.out.println("Error Message:" + oe.getErrorMessage());
System.out.println("Error Code:" + oe.getErrorCode());
System.out.println("Request ID:" + oe.getRequestId());
System.out.println("Host ID:" + oe.getHostId());
} catch (ClientException ce) {
System.out.println("Caught an ClientException, which means the client encountered "
+ "a serious internal problem while trying to communicate with OSS, "
+ "such as not being able to access the network.");
System.out.println("Error Message:" + ce.getMessage());
} finally {
if (ossClient != null) {
ossClient.shutdown();
}
}
}
}PHP
OSS SDK for PHP 2.7.0 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;
// Obtain access credentials from 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";
// Specify the full path of the object. Example: exampledir/exampleobject.jpg. Do not include the bucket name in the full path.
$object = "src.jpg";
// Specify the full path of the local file. Example: D:\\dest.jpg. If a file that has the same name already exists in the path, the processed image overwrites the file. Otherwise, the processed image is saved in the path.
// If you specify only the name of the local file such as dest.jpg without specifying the local path of the file, the processed image is saved to the local path of the project to which the sample program belongs.
$download_file = "D:\\dest.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);
// Set the absolute quality of the source image to 80%.
$image = "image/quality,Q_80";
$options = array(
OssClient::OSS_FILE_DOWNLOAD => $download_file,
OssClient::OSS_PROCESS => $image);
// Save the processed image to your local computer.
$ossClient->getObject($bucket, $object, $options); Python
OSS SDK for Python 2.18.4 or later is required.
# -*- coding: utf-8 -*-
import oss2
from oss2.credentials import EnvironmentVariableCredentialsProvider
# Obtain access credentials from 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.
## 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)
# Specify the name of the source image. 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 = 'src.jpg'
# Specify the name of the processed image.
new_pic = 'D:\\dest.jpg'
# Set the absolute quality of the source image to 80%.
image = 'image/quality,Q_80'
bucket.get_object_to_file(key, new_pic, process=image)Go
OSS SDK for Go 3.0.2 or later is required.
package main
import (
"fmt"
"os"
"github.com/aliyun/aliyun-oss-go-sdk/oss"
)
func HandleError(err error) {
fmt.Println("Error:", err)
os.Exit(-1)
}
func main() {
// Obtain access credentials from 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.
client, err := oss.New("https://oss-cn-hangzhou.aliyuncs.com", "", "", oss.SetCredentialsProvider(&provider), oss.AuthVersion(oss.AuthV4), oss.Region("cn-hangzhou"))
if err != nil {
HandleError(err)
}
// Specify the name of the bucket in which the source image is stored. Example: examplebucket.
bucketName := "examplebucket"
bucket, err := client.Bucket(bucketName)
if err != nil {
HandleError(err)
}
// Specify the name of the source image. 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.
sourceImageName := "src.jpg"
// Specify the name of the processed image.
targetImageName := "D://dest.jpg"
// Set the absolute quality of the source image to 80%.
image := "image/quality,Q_80"
err = bucket.GetObjectToFile(sourceImageName, targetImageName, oss.Process(image))
if err != nil {
HandleError(err)
}
}Use the OSS 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, see GetObject.
You can process images by using quality adjustment parameters when you call the GetObject operation.
GET /oss.jpg?x-oss-process=image/quality,Q_80 HTTP/1.1
Host: oss-example.oss-cn-hangzhou.aliyuncs.com
Date: Fri, 28 Oct 2022 06:40:10 GMT
Authorization: OSS qn6q**************:77Dv****************