Background

background - bg - bg_<color value>

Value	Type	Description
color value	string, hex	Default Value: white Value can be; 3-8 Digit RGB or RGBA Hex (without #) A named color Eg. bg_orange, bg_FFF, bg_C40087

Changes the background color of an image if there is any space left after cropping.

https://demo.imagemash.io/w_500,h_200,c_contain,bg_palegreen/eg1.png

To see all named colors: https://drafts.csswg.org/css-color/#named-colors

This function does not change the default background of an image.

Auto

Auto property calculates the proper background color for your image's theme

https://demo.imagemash.io/w_500,h_200,c_contain,bg_auto/eg1.png