1. Customize the default theme with your colors, fonts, etc.
2. Export the customized theme.
Save the theme as a JSON file.
3. Encode the background image you want to use in Base64.
Here is a site that will do it for you: Image to Base64 Converter - Encode Images to Base64 - Online - Browserling Web Developer Tools
I took our default slide master in PowerPoint, added the BlueGranite logo, and saved as PNG. Then I took that file and used the above site to encode as Base64. Here's the final JSON file I used if you'd like to utilize it as well.
4. Open the JSON theme in a text editor.
Add the following snippet to the “visualStyles” section of the JSON theme you saved in Step 2:
"name": "<<change this to a name you prefer>>",
"url": "data:image/jpeg;base64,<<insert the Base64 code here>>"
Everything between the “<<” and the “>>” needs to be replaced including the “<<”/”>>”.
5. Browse and import the updated theme.
Here’s what the BGTheme looks like with a blank page in Power BI:
There are many other customizable settings you can specify in a custom theme that aren’t exposed thru the “Customize current theme” option from the View menu. You can go so far as to customize the look-and-feel of each individual visualization type.
If you need help don’t hesitate to contact us here at BlueGranite! And join us for Power BI Office Hours each month to learn even more! If you need advice and guidance on the current standing or future enhancements of your setup, let BlueGranite offer some words of wisdom, contact us today!