If you do not have a suitable panoramic picture, you can crop it on standard format picture (4/3 or 16/9).
Here's how to proceed:
1. Go to the site convertimage.net.
2. Go to part 1: "Choose the output picture format :".
Click on the icon "JPG".
3. Go to part 3: "Select your image".
Click on "select your image" and select in your folders the chosen picture.
Click on the icon to see the "YES" from "I agree to the terms of use".
Finally, click on "Convert this image".
4. Define an area on the image that has one of the following criteria:
- Dimension of 1920x252 pixels OR
- A width/height ratio of about 7.6.
Then click on "Validate".
5. Click on "Download the image".
Save it under a new name so you do not overwrite the original image.
6. Use this image as an introduction panoramic picture.