Watermarking Images

This document helps you understand image watermarks.

Operation Scenarios

ZOS supports image watermarks and text watermarks to protect the ownership of images.

Constraints and Restrictions

Image watermarks can only be in the JPG, PNG, WebP, and TIFF formats.
The size of a source image cannot exceed 20 MB. The width or height cannot exceed 30,000 px, and total pixels cannot exceed 250 million px.
Watermark preprocessing does not support the "|" splicing operator.
Image watermarks and the source image must be in the same bucket.

Description

Operator: watermark

Parameters for adding an image or text watermark must be URL Base64 encoded. Encoding steps: Encode the content to Base64 and replace the code in the result.

Basic Parameters

Parameter Name	Purpose	Value	Required
t	Transparency of an image or text watermark	[0,100] Default value: 100	No
x	Horizontal distance from the image edge	[0,4096] Default value: 10	No
y	Vertical distance from the image edge	[0,4096] Default value: 10	No
g	Specifies the watermark position on the image.	nw: top-left (default) north: top-center ne: top-right west: middle-left center: center east: middle-right sw: bottom-left south: bottom-center se: bottom-right	No

Different positions and their reference points are shown in the diagram below.

Watermarking Images Parameters

Parameter Name	Purpose	Value	Required
image	Specifies the object name of the watermark image. The watermark image must be stored in the same bucket as the source image.	Base64-encoded string After encoding, replace the string "/" with "_". The watermark image may be attached directly to the source image or after preprocessing.	Yes

Example

Set the general transparency value t to 50 after watermarking.

Direct Processing

Assume the watermark image is shuiyin.png in the same bucket as the source image, the content to be encoded is "shuiyin.png" and the encoded string is c2h1aXlpbi5wbmc=. The specific request is:

image/watermark, image_c2h1aXlpbi5wbmc=, t_50

Preprocess Watermark

Use the image shuiyin.png. To scale the watermark by 50% and rotate it 180°, Base64 encode shuiyin.png?x-zos-process=image/resize,p_50/rotate,180. After encoding, the result is:

c2h1aXlpbi5wbmc/eC16b3MtcHJvY2Vzcz1pbWFnZS9yZXNpemUscF81MC9yb3RhdGUsMTgw

Replace "/" in the above result with "_". Final request:

image/watermark,image_c2h1aXlpbi5wbmc_eC16b3MtcHJvY2Vzcz1pbWFnZS9yZXNpemUscF81MC9yb3RhdGUsMTgw,t_50

Text Watermark Parameters

Parameter Name	Purpose	Value	Required
text	Specifies the text watermark content.	Base64-encoded string, with "/" in the encoded result replaced by "_".	Yes
color	Specifies the color of the text watermark.	RGB color value Default: FFFFFF (white)	No
size	Specifies the font size of the text watermark.	Default value: 40	No
type	Specifies the font type of the text watermark.	Supported English fonts, such as Arial Supported Chinese fonts include Microsoft YaHei, Heiti, Kaishu, and YouYuan Default: Kaishu	No
rotate	Specifies the clockwise rotation angle of the text watermark.	[0,360] Default value: 0	No

Example

Add the text "Chinatelecom" to the image as a watermark, specify the Heiti font, and set the color to red (FF0000). Set the font size to 40, add it to the bottom right of the source image, and set the opacity to 80. The encoded result of "Chinatelecom" is Q2hpbmF0ZWxlY29t. The specific request is:

image/watermark,text_Q2hpbmF0ZWxlY29t,type_heiti,color_FF0000,size_40,g_se,t_80

FAQ

1. What are the common color codes?

#FFFFFF — White

#0000FF — Blue

#FF0000 — Red

#00FF00 — Green

#808080 — Gray

#FFFF00 — Yellow

#000000 — Black

2. Can I add a background color while adding an image watermark?

A: No.

3. How can I use a local image as a watermark image?

A: Upload the local image to the same bucket as the source image to be watermarked.

Zettabyte Object Storage