Overview

CI’s Image Watermarking feature is implemented using the watermark API. Currently, only image watermarks stored in CI are supported. 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.

An image can be processed:

• Upon download
• Upon upload
• In cloud

Note：

• You can overlay up to 10 image watermarks over a single image.
• An animated image cannot be used as a watermark.

API Format

1. Processing upon download

download_url?watermark/1/image/<encodedURL>
                      /gravity/<gravity>
                      /dx/<dx>
                      /dy/<dy>
                      /blogo/<type>

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/1/image/<encodedURL>
                      /gravity/<gravity>
                      /dx/<dx>
                      /dy/<dy>
                      /blogo/<type>"
}]
}

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/1/image/<encodedURL>
                      /gravity/<gravity>
                      /dx/<dx>
                      /dy/<dy>
                      /blogo/<type>"
}]
}

Note：

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

Parameters

In the code above, watermark is the operation name and the number 1 indicates that the watermark is an image.

Parameter	Description
download_url	URL of the input image, formatted as &dxlt;BucketName-APPID>.cos.&dxlt;Region>.myqcloud.com/&dxlt;picture name> Example: examplebucket-1250000000.cos.ap-shanghai.myqcloud.com/picture.jpeg
/image/	URL-safe Base64-encoded URL of the image watermark. For example, if the image watermark URL is http://examplebucket-1250000000.cos.ap-shanghai.myqcloud.com/shuiyin_2.png, you should set this parameter to aHR0cDovL2V4YW1wbGVidWNrZXQtMTI1MDAwMDAwMC5jb3MuYXAtc2hhbmdoYWkubXlxY2xvdWQuY29tL3NodWl5aW5fMi5wbmc.
/gravity/	Position of the image 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
/blogo/	Adaptation mode for an image watermark that is larger than the input image. Valid values: 1: scales the image watermark to the size of the input image. 2: crops the image watermark to the size of the input image.
/scatype/	Scaling mode for the image 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 image 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) Example: http://examples-1251000004.cos.ap-shanghai.myqcloud.com/sample.jpeg?watermark/1/image/xxxxxxx/scatype/3/spcent/250
/dissolve/	Opacity of the image watermark. Value range: 1−100. Default value: 90 (meaning 90% opacity)

Note：

An image watermark must:

• Be stored in the same bucket as the input image.
• Have a URL containing a COS domain name (a CDN acceleration domain name such as examplebucket-1250000000.file.myqcloud.com/shuiyin_2.png is unsupported) and be accessible (if the image watermark is set to private-read, it must carry a signature).
• Have a URL starting with http://. Note that “http://” cannot be omitted or changed to “https://”. For example, examplebucket-1250000000.cos.ap-shanghai.myqcloud.com/shuiyin_2.png and https://examplebucket-1250000000.cos.ap-shanghai.myqcloud.com/shuiyin_2.png are invalid watermark URLs.

3x3 Grid Position Diagram

The 3x3 grid position diagram is as follows. Once you specify the gravity parameter to position your watermark, the corresponding red dot becomes the reference point of the square, 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 and the watermark will be centered horizontally.
• If gravity is set to west or east, dy is invalid and the watermark will be centered vertically.

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: adding an image watermark

http://examples-1251000004.cos.ap-shanghai.myqcloud.com/sample.jpeg?watermark/1/image/aHR0cDovL2V4YW1wbGVzLTEyNTEwMDAwMDQucGljc2gubXlxY2xvdWQuY29tL3NodWl5aW4uanBn/gravity/southeast

After an image watermark is added:

Example 2: adding an image 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/1/image/aHR0cDovL2V4YW1wbGVzLTEyNTEwMDAwMDQucGljc2gubXlxY2xvdWQuY29tL3NodWl5aW4uanBn/gravity/southeast

Note：

You can obtain the value of &dxlt;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