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Quality Change

Last updated: 2024-02-18 10:36:35

    Feature Overview

    CI uses the imageMogr2 API to adjust the quality of an image.
    An image can be processed:
    During download
    During upload
    In the cloud
    Note:
    This API supports images in JPG, WebP, TPG, HEIF, or AVIF format.

    API Sample

    1. Processing during download

    GET /<ObjectKey>?imageMogr2/quality/<Quality>
                               /rquality/<quality>
                               /lquality/<quality> 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/quality/<Quality>
                           /rquality/<quality>
                           /lquality/<quality>"
      }]
    }
    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/quality/<Quality>
                           /rquality/<quality>
                           /lquality/<quality>"
      }]
    }
    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

    Operation name: quality.
    Parameter
    Description
    ObjectKey
    Object name, such as folder/sample.jpg.
    /quality/<Quality>
    Absolute quality of the image. The value can be 0–100. Use the value of the original image quality (default) or the specified quality, whichever is smaller. If there is an exclamation mark (!) after <Quality> (such as 90!), the specified quality value is forcibly used.
    /rquality/<quality>
    Image quality relative to that of the input image. The value can be 0−100. For example, if the input image quality is 80 and rquality is set to 80, the quality of the output image will be 64 (80 * 80%).
    /lquality/<quality>
    Minimum quality of the image. Value range: 0−100.
    If the input image quality is 85 and lquality is set to 80, the quality of the output image will be 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 fails to be processed because the image is too large or a parameter value exceeds the limit, the input image will be returned with no error reported.

    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, see Persistent Image Processing and use the processing during upload or processing in-cloud data feature.

    Sample 1: Setting an absolute quality

    This example sets the absolute quality to 60:
    http://examples-1251000004.picsh.myqcloud.com/sample.jpeg?imageMogr2/quality/60
    Output:
    
    

    Sample 2: Setting a relative quality

    This example sets the relative quality to 60:
    http://examples-1251000004.cos.ap-shanghai.myqcloud.com/sample.jpeg?imageMogr2/rquality/60
    Output:
    
    

    Sample 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 concatenated with other processing parameters by an ampersand (&).
    http://examples-1251000004.cos.ap-shanghai.myqcloud.com/sample.jpeg?q-sign-algorithm=<signature>&imageMogr2/rquality/60
    Note:
    You can get the value of <signature> as instructed in 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 sample for your reference (it might have expired or become inaccessible). For more information, see Upload via Pre-Signed URL.
    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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