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Text Watermark

Last updated: 2022-10-19 12:15:46

    Feature Overview

    COS's real-time text watermarking feature is implemented through the watermark API provided by CI. An 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, its total number of pixels (width x height x number of frames) cannot exceed 250 million.

    Note:

    Image processing is charged by CI. For detailed pricing, see Image Processing Fees.

    This feature supports processing:

    • During download
    • During upload
    • In the cloud

    API Sample

    1. Processing during download

    GET /<ObjectKey>?watermark/2/text/<encodedText>
                          /font/<encodedFont>
                          /fontsize/<fontSize>
                          /fill/<encodedColor>
                          /dissolve/<dissolve>
                          /gravity/<gravity>
                          /dx/<dx>
                          /dy/<dy>
                          /batch/<type>
                          /degree/<degree>
                          /shadow/<shadow> HTTP/1.1
    Host: <BucketName-APPID>.cos.<Region>.myqcloud.com
    Date: <GMT Date>
    Authorization: <Auth String>
    
    Note:

    Spaces and line breaks above are for readability only and can be ignored.

    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": "watermark/2/text/<encodedText>
                          /font/<encodedFont>
                          /fontsize/<fontSize>
                          /fill/<encodedColor>
                          /dissolve/<dissolve>
                          /gravity/<gravity>
                          /dx/<dx>
                          /dy/<dy>
                          /batch/<type>
                          /degree/<degree>
                          /shadow/<shadow>"
    }]
    }
    
    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": "watermark/2/text/<encodedText>
                          /font/<encodedFont>
                          /fontsize/<fontSize>
                          /fill/<encodedColor>
                          /dissolve/<dissolve>
                          /gravity/<gravity>
                          /dx/<dx>
                          /dy/<dy>
                          /batch/<type>
                          /degree/<degree>
                          /shadow/<shadow>"
    }]
    }
    
    Note:

    Parameters

    In the code above, watermark is the operation name and the number 2 indicates that the watermark is text.

    Parameter Description
    ObjectKey Object name, such as folder/sample.jpg.
    /text/ Watermark text, which must be URL-safe Base64-encoded.
    /font/ Font of the text, which must be URL-safe Base64-encoded. Default font: Tahoma.ttf (see Supported Fonts).
    /fontsize/ Font size in pt. Default value: 13. To scale the text watermark proportionally based on the original image, convert the text watermark to a PNG image. For more configuration information, see Image Watermarking.
    /fill/ Font color. The value must be in hexadecimal format, for example, #FF0000. For format conversion, see RGB Color Codes Chart. The value must be URL-safe Base64-encoded. Default value: #3D3D3D (gray).
    /dissolve/ Text opacity. Value range: 1−100. Default value: 90 (meaning 90% opacity)
    /gravity/ Position of the text watermark, which is a square in a 3x3 grid. Default value: SouthEast.
    /dx/ Horizontal offset in px. Default value: 0.
    /dy/ Vertical offset in px. Default value: 0.
    /batch/ Whether to tile the text watermark. If this parameter is set to 1, the text watermark will be tiled across the input image.
    /degree/ Angle to rotate the text watermark. This parameter will take effect only when /batch/ is set to 1. Value range: 0−360. Default value: 0.
    /shadow/ Text shadow effect. Value range: 0−100. Default value: 0 (no shadow).

    3x3 Grid Position Diagram

    The 3x3 grid position diagram is as follows. Once you specify the gravity parameter for an operation, the corresponding red dot becomes the reference point, and offsets will be relative to this point.

    Note:

    • If gravity is set to center, dx and dy are invalid.
    • If gravity is set to north or south, dx is invalid.
    • If gravity is set to west or east, dy is invalid.

    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: Adding a text watermark

    http://examples-1251000004.cos.ap-shanghai.myqcloud.com/sample.jpeg?watermark/2/text/6IW-6K6v5LqRwrfkuIfosaHkvJjlm74/fill/IzNEM0QzRA/fontsize/20/dissolve/50/gravity/northeast/dx/20/dy/20/batch/1/degree/45
    

    Output:

    Sample 2: Adding a text watermark 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>&watermark/2/text/6IW-6K6v5LqRwrfkuIfosaHkvJjlm74/fill/IzNEM0QzRA/fontsize/20/dissolve/50/gravity/northeast/dx/20/dy/20/batch/1/degree/45
    
    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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