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How to add a watermark to pictures with MiniMagick and Ruby

Tagged watermark, overlay, caption, mini_magick, ruby, gravity, draw  Languages ruby

This code can be used to add a watermark to pictures:

require 'rubygems'
require 'mini_magick'

# Read the image
img = MiniMagick::Image.from_file("the_picture.jpg")

# 0,0 0,0 = add the watermark at coordinates: x, y, set watermark size to auto with 0,0
img.draw 'image Over 0,0 0,0 "the_watermark.gif"'


How to add a watermark to the bottom-left corner?

To add a watermark to the bottom-left corner, you need to use the combine_options method to pass more than one command plus parameters to MiniMagick (gravity and draw commands):

require 'rubygems'
require 'mini_magick'

img = MiniMagick::Image.from_file("the_image.jpg")

img.combine_options do |c|
  c.gravity 'SouthWest'
  c.draw 'image Over 0,0 0,0 "the_watermark.gif"'



See mogrify's documentation for details on how to use the draw command.

If you get this error it might mean that mogrify can't find the watermark image, or that the syntax is incorrect:

mogrify: Non-conforming drawing primitive definition image'.