Google never takes a break from improving and adding new features to its products and services. Google has now introduced custom gmail themes for its users. Earlier we had three kinds of categories for gmail themes, Color themes, HD themes and classic themes. The fourth option being the custom gmail themes will personalize your gmail inbox background with any photo.
The Gmail background image feature will slowly roll out across all gmail acccounts in the coming days. To check if your gmail inbox has already got the background image option, go to Settings > Themes page and notice the custom themes option there.
Personalize your Inbox With Custom Gmail Themes

Changing gmail themes once in a while does uplift mood a bit, there is no harm in getting a fresh makeover of your gmail inbox. Most other email service providers do offer themes for inbox but it is only limited to color change. At that time also gmail was ahead of others, it not only had color themes but many more classic and hd themes.
Now with custom gmail themes you can easily add a background image by using a wallpaper on your computer, a photo from your last vacation or a memorable photo. In custom gmail themes you get to choose from a Light or Dark theme then further you select a photo of your choice to set it as gmail background image.

To select a background image for gmail go to Settings > Themes > Custom Themes. There are various options to select an image:
- Choose one of the featured image.
- My Photos which are already uploaded photos on google account.
- Photos uploaded from Google+ app for android and iPhone.
- Upload a photo from computer.
- Paste an image URL from web.
The image size does not matter as it will automatically stretch the image to accomodate to background, though it is adviced to use a higher resolution photo for a better view. Whenever you get bored of the inbox look, just change the gmail background image from the custom gmail themes option.
Watch the promo video for custom gmail theme :
