Image manipulation library for web written in Go.
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watermark.go Initial working version. 2020-02-09 18:32:32 +02:00


Image manipulation library for web written in Go.


Currently webimg library supports following functionality:

  • Watermarking add PNG logo on top of JPEG file at desired bottom-right offset in pixels, set desired transparency of PNG logo.

Use in your Go project

Download sources to your GOPATH:

go get -d -u

Mind the arguments: -d flag instructs get to stop after downloading the packages; -u flag instructs get to use the network to update the named packages and their dependencies.

Include in your application:

import (

And then call function:

// Input image, watermark image, result image, bottom-right offset X, bottom-right offset Y, watermark alpha
doWatermark := webimg.Watermark("smplayer_preferences.jpg", "watermark_inretio-logo.png", "result_img.jpg", 30, 30, 70)
if doWatermark != nil {
  fmt.Println("There was an error watermarking image...")

Currently the library is able to watermark JPEG image with PNG watermark (which should have transparent background). You can set offset in pixels from bottom-right corner (in example 30, 30) and transparency of watermark image (in example 70, scale is 0-255 where 0 is solid and 255 is transparent).


Sources are published on privately hosted instance of Gitea: To get sources either use go get as described above or clone repository:

git clone


Follow webimg blog for news and changelog from fediverse:

If you have any feedback or ideas, drop me an email at or on Mastodon at