A few weeks ago I saw a small but very useful hack if you’re working with Power BI Themes. Did you know that you can create a Theme with a background image? Let me show you how!

What is a Theme in Power BI?

Power BI Report Themes helps you to apply design changes to your entire report. With a Theme you can specify what the default color of your visuals should be, changing icon sets, or applying default visual formatting like title text size. Further details can be found here: https://docs.microsoft.com/en-us/power-bi/create-reports/desktop-report-themes

Once a Theme is created you can save it as JSON file and distributed it to your whole organization. Like with every other JSON file you can of course modify it as wished. In our case we wish to add a background image because background images are not saved through the Desktop in the JSON file.

How to create a Theme

Once Power BI Desktop is opened select the View Tab, expand Themes, and hit Customize current theme.

A new window will pop up in which you can customize your current Theme. In my case I choose to go with darker colors in general. You can also customize your Text, Visuals, Page, and Filter pane. Once done hit the Apply button.

You’ll see now that the current Theme is used in your Power BI report. Last step is to save the current Theme as JSON.

If you wish you can try to add a background image in your report but this will not be saved in the Theme / JSON file.

Once saved I open the JSON file in Notepad++ and format it as JSON format through the JSTool plugin. As we can see the data colors has been saved in our JSON file (and nothing else).

To be able to add now a background image we need to add a code snippet and convert our background image to base64 format. Let me walk you through the steps. First, we add following code snippet after the dataColors line.

,”visualStyles”: {“page”: {“*”: {“background”: [{“image”: {“name”: “Demo”,”scaling”: “Fit”,”url”: “data:image/jpg;base64, ” },”transparency”: 50}]}}}

Now we can add our base64 formatted image after the comma of base64 but it has to be before the quote. To convert an image into base64 just search for an online service which can do so. In my case I’m using https://onlinejpgtools.com/convert-jpg-to-base64 and simply drag my image in the necessary field. Once done you’ll get the code right away on the right sight. Hit the “Copy to clipboard” button to have it in your clipboard.

If your image is a PNG just replace the red marked part of your code to be PNG instead of JPG.

Finally I have to save my JSON file and import it into every Power BI report file I wish to use my new Theme.

As you can see the background image is saved within the Theme with the correct settings. In my case I set the transparency to 50%.

Please let me know if this post was helpful and give me some feedback. Also feel free to contact me if you have any questions.

If you’re interested in the files used in this blog check out my GitHub repo https://github.com/PBI-Guy/blog