tencent cloud

Feature Description

Image compression is the process of downsizing an image as much as possible without sacrificing quality so that it can be stored at a lower cost and accessed more quickly.

COS launched the WebP compression feature based on CI to convert images to .webp format, which is superior to .jpg in terms of compression. A .webp image is over 25% smaller than a .jpg image with the same quality. This format is suitable for multi-terminal use cases.

Restrictions

• Format: Images in JPG, PNG, BMP, GIF, HEIF, or AVIF format can be converted to WebP format.
• Size: The input image cannot be larger than 32 MB, with its width and height not exceeding 30,000 pixels respectively, and the total number of pixels not exceeding 250 million. The width and height of the output image cannot exceed 9,999 pixels respectively. For an animated input image, the total number of pixels (width * height * number of frames) cannot exceed 250 million.
• Frames (for animated images): For GIF images, the number of frames cannot exceed 300.

Directions

COS uses CI's imageMogr2 API to provide the WebP compression feature.

This feature supports processing:

• During download
• During upload
• In the cloud

Note：

• WebP compression is a paid service charged by CI at the basic image processing prices. For detailed pricing, see Image Processing Fees.
• If an image is converted to WebP format, some browsers may not be able to read its EXIF data. As a result, the image cannot be rotated. You can add the auto-orient parameter to rotate the input image first before compressing it (see Rotation) .
• WebP compression inherits the quality parameters of the input image by default. You can adjust the compression ratio by modifying the image quality as instructed in Quality Change.

API Sample

1. Processing during download

GET /<ObjectKey>?imageMogr2/format/webp HTTP/1.1
Host: <BucketName-APPID>.cos.<Region>.myqcloud.com
Date: <GMT Date>
Authorization: <Auth String>

2. Processing during upload

PUT /<ObjectKey> HTTP/1.1
Host: <BucketName-APPID>.cos.<Region>.myqcloud.com
Date: GMT Date
Authorization: Auth String
Pic-Operations: 
{
"is_pic_info": 1,
"rules": [{
  "fileid": "exampleobject",
  "rule": "imageMogr2/format/webp"
}]
}

Note：

Pic-Operations is a JSON string. Its parameters are as described in Persistent Image Processing.

3. Processing in-cloud data

POST /<ObjectKey>?image_process HTTP/1.1
Host: <BucketName-APPID>.cos.<Region>.myqcloud.com
Date: GMT Date
Content-length: Size
Authorization: Auth String
Pic-Operations: 
{
"is_pic_info": 1,
"rules": [{
  "fileid": "exampleobject",
  "rule": "imageMogr2/format/webp"
}]
}

Note：

• Authorization: Auth String (for more information, see Request Signature).
• When this feature is used by a sub-account, relevant permissions must be granted. For more information, see Authorization Granularity Details.

Parameters

Parameter	Description
ObjectKey	Object name, such as folder/sample.jpg.
/format/<Format>	Compression format, which is webp here.

Samples

Note：

Processing during download is used as an example here, which does not store the output image in a bucket. If you need to store the output image, use processing during upload or processing in-cloud data instead.

Assume the input image is a 1,335.2 KB image in PNG format.

You can convert the image to WebP format by using the following request URL:

http://example-1258125638.cos.ap-shanghai.myqcloud.com/sample.png?imageMogr2/format/webp

Output:

Compression ratio comparison

Format	Image Size
PNG (input image)	1,335.2 KB
WebP	65 KB (compression ratio: 95.13%)