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Text Watermark

Last updated: 2024-06-12 15:20:05

    Feature Overview

    COS uses the watermark API provided by CI to add text watermarks in real time.
    Note:
    Image Processing is charged by CI. For detailed pricing, see Basic image processing fee in Billing and Pricing.
    An image can be processed:
    Upon download
    Upon upload
    In cloud

    Restrictions

    Format: JPG, BMP, GIF, PNG, and WebP images can be processed, and HEIF images can be decoded and processed.
    Static image size: The input image cannot be larger than 32 MB. Its dimensions cannot exceed 50,000 pixels and its resolution cannot exceed 250 million pixels. The dimensions of the output image cannot exceed 50,000 pixels.
    WebP image size: The input image cannot be larger than 32 MB. Its dimensions cannot exceed 16,383 pixels and its resolution cannot exceed 250 million pixels. The dimensions of the output image cannot exceed 16,383 pixels.
    Animated image size: For the input or output 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.

    API Format

    1. Processing upon 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 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": "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:
    Authorization: Auth String (see Request Signature for more information)
    When this feature is used by a sub-account, relevant permissions must be granted as instructed in Authorization Granularity Details.

    Parameters

    In the code above, watermark is the operation name and the number 2 indicates that the watermark is a text.
    Parameter
    Description
    ObjectKey
    Object name, such as folder/sample.jpg.
    /text/
    Watermark text, which must be Base64 URL-safe 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 pixels. Default value: 0
    /dy/
    Vertical offset in pixels. 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.
    /spacing/
    The horizontal and vertical spacing (in tile mode) relative to the width and height of the text watermark image, respectively, in percentage. Value range: [0,100]. Default value: 10
    /degree/
    Angle to rotate text watermarks. This parameter is valid 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, indicating no shadow.
    /scatype/
    Scaling mode for the text watermark (relative to the input image). This parameter must be used together with /spcent/. Valid values:
    1: Scales by width.
    2: Scales by height.
    3: Scales by area.
    /spcent/
    Scale ratio of the watermark, in permillage. This parameter must be used together with /scatype/. Value range:
    1−1000 (if /scatype/ is set to 1)
    1−1000 (if /scatype/ is set to 2)
    1−250 (if /scatype/ is set to 3)

    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.

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

    Example 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
    After text watermarks are added:
    
    

    Example 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 joined with other processing parameters using 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 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 not be valid or accessible anymore). 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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