You can add color filters to your mash. Filters are available on the iOS app with a Pro subscription.
Add a filter
From the mash editor, tap Filters.
The filters are grouped into named categories—Enhanced, Vibrant, and others—that you scroll through sideways. Tap one to select it.
The filter shows on your mash preview.
Tap the yellow checkmark to finish, or the X at the top left to leave the mash as it was.

