When adding text to an image, you will want to make sure the text is readable. Writing over a picture slide can be challenging when the picture is busy and full of color. To effectively add text over images, add an image overlay to your Google Slide. The examples below show a slide without and with an image overlay.
To accomplish this effect, follow the below steps:Insert an image to a slide. Resize image so that it covers the slide Add a rectangle and resize to cover the image
Here’s an animation that shows you the entire process: