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Quality Change

Terakhir diperbarui:2021-10-22 14:17:32

    Overview

    COS uses the imageMogr2 API provided by CI to adjust the quality of an image.

    An image can be processed:

    • Upon download
    • Upon upload
    • In cloud
    Note:

    • Image processing is charged by CI. For detailed pricing, please see the image processing prices of CI.
    • This API supports images in JPG, WebP, TPG, HEIF, or AVIF format.

    API Format

    1. Processing upon download

    download_url?imageMogr2/quality/<Quality>
                         /rquality/<quality>
                         /lquality/<quality>
    

    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/quality/<Quality>
                         /rquality/<quality>
                         /lquality/<quality>"
    }]
    }
    

    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/quality/<Quality>
                         /rquality/<quality>
                         /lquality/<quality>"
    }]
    }
    
    Note:

    Authorization: Auth String (For more information, please see Request Signature.)

    Parameters

    Operation: quality

    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
    /quality/&dxlt;Quality> Absolute quality of the image. Value range: 0−100. Default value: quality of the input image. The smaller value between the input image quality and the specified quality is used. If there is an exclamation mark (!) after &amp;dxlt;Quality&amp;dxgt; (for example, 90!), the specified quality is used.
    /rquality/&dxlt;quality> Relative quality of the image, relative to that of the input image. Value range: 0−100. For example, if the input image quality is 80 and rquality is set to 80, the quality of the output image is 64 (that is, 80 x 80%).
    /lquality/&dxlt;quality> The lowest quality of the output image. Value range: 0−100.
  • If the input image quality is 85 and lquality is set to 80, the quality of the output image is 85.
  • If the input image quality is 60 and lquality is set to 80, the quality of the output image will be improved to 80.
  • /ignore-error/1 If this parameter is carried and the image failed to be processed because it is too large, the input image will be returned with no error reported.

    Examples

    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, please see Persistent Image Processing and use Processing upon upload or Processing in-cloud data.

    Example 1: setting absolute quality

    This example sets the absolute quality to 60:

    http://examples-1251000004.picsh.myqcloud.com/sample.jpeg?imageMogr2/quality/60
    

    Output image:

    Example 2: setting relative quality

    This example sets the relative quality to 60:

    http://examples-1251000004.cos.ap-shanghai.myqcloud.com/sample.jpeg?imageMogr2/rquality/60
    

    Output image:

    Example 3: setting the relative quality to 60 with a signature carried

    This example processes the image in the same way as in the example above except that a signature is carried. The signature is joined with other processing parameters using an ampersand (&):

    http://examples-1251000004.cos.ap-shanghai.myqcloud.com/sample.jpeg?q-sign-algorithm=<signature>&imageMogr2/rquality/60
    
    Note:

    You can obtain the value of <signature> by referring to Request Signature.

    Notes

    To prevent unauthorized users from accessing or downloading the input image by using a URL that does not contain any processing parameter, you can add the processing parameters to the request signature, making the processing parameters the key of the parameter with the value left empty. The following is a simple example for your reference (it might have expired or become inaccessible). For more information, please see Request Signature.

    http://examples-1251000004.cos.ap-shanghai.myqcloud.com/sample.jpeg?q-sign-algorithm=sha1&q-ak=AKID********************&q-sign-time=1593342360;1593342720&q-key-time=1593342360;1593342720&q-header-list=&q-url-param-list=watermark%252f1%252fimage%252fahr0cdovl2v4yw1wbgvzlteyntewmdawmdqucgljc2gubxlxy2xvdwquy29tl3nodwl5aw4uanbn%252fgravity%252fsoutheast&q-signature=26a429871963375c88081ef60247c5746e834a98&watermark/1/image/aHR0cDovL2V4YW1wbGVzLTEyNTEwMDAwMDQucGljc2gubXlxY2xvdWQuY29tL3NodWl5aW4uanBn/gravity/southeast
    

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