Usage: fill(color[,fill_transparent])

This filter permit to return an image sized exactly as requested wherever is its ratio by filling with chosen color the missing parts. Usually used with "fit-in" or "adaptive-fit-in"

• color - the color name (like in HTML) or hexadecimal RGB expression without the "#" character (see https://en.wikipedia.org/wiki/Web_colors for example).

  If color is "transparent" and the format supports transparency, the filling color is transparent.

  If color is "auto", a color is smartly chosen (based on the image pixels) as the filling color.

• fill_transparent - a boolean to specify whether transparent areas of the image should be filled or not. Accepted values are either true, false, 1 or 0. This argument is optional and the default value is false.

As original image is : Original picture

http://localhost:8888/unsafe/fit-in/300x300/filters:fill(blue)/https://github.com/globocom/thumbor/wiki/tom_before_brightness.jpg

Picture after the fill(blue) filter

http://localhost:8888/unsafe/fit-in/300x300/filters:fill(f00)/https://github.com/globocom/thumbor/wiki/tom_before_brightness.jpg

Picture after the fill(f00) filter

http://localhost:8888/unsafe/fit-in/300x300/filters:fill(add8e6)/https://github.com/globocom/thumbor/wiki/tom_before_brightness.jpg

Picture after the fill(add8e6) filter

http://localhost:8888/unsafe/fit-in/300x300/filters:fill(auto)/https://github.com/globocom/thumbor/wiki/tom_before_brightness.jpg

Picture after the fill(auto) filter (since 3.7.1)