WebP Compression

Last updated: 2021-12-06 11:41:57

    Overview

    Image compression refers to reducing an image’s size as much as possible without changing its quality, to reduce its cost for storage and traffic and speed up access.

    CI launched the WebP compression feature to convert images into WebP format, a format that outperforms JPG in terms of compression. WebP offers over 25% smaller file sizes at the same quality compared with JPG, making it suitable for more clients.

    Restrictions

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

    Use Directions

    CI uses the imageMogr2 API to provide the WebP compression feature.

    An image can be processed:

    • Upon download
    • Upon upload
    • In cloud
    Note:

    • WebP compression is billed at basic image processing rates.
    • If an image is converted into WebP, 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 (see Rotation) before compressing it.

    API Format

    1. Processing upon download

    download_url?imageMogr2/format/webp
    

    2. Processing upon 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"
    }]
    }
    

    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:

    Processing upon 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 upon upload or Processing in-cloud data instead.

    Parameters

    Parameter Description
    download_url URL of the input image, formatted as &amp;dxlt;BucketName-APPID>.cos.&amp;dxlt;Region>.myqcloud.com/&amp;dxlt;picture name>
    Example: examplebucket-1250000000.cos.ap-shanghai.myqcloud.com/picture.jpeg
    /format/&dxlt;Format> Compression format, which is webp

    Examples

    Assume that the input image is a 1,335.2 KB image in PNG format, as shown below:
    img

    You can convert the image into WebP format using the following URL:

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

    Output image:
    img

    Compression ratio comparison

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