If you want to use a presentation app like PowerPoint to showcase images only, or images with captions, you’ll get a nicer and more consistent overall look if you follow the steps below instead of simply inserting images into the default slide layout.
STEP 1: INSERT INTO BACKGROUND
As long as your images are of an appropriate quality and size, you can insert them into the background of each slide, which will expand the image to fill the whole slide.
To do that, start by choosing blank slide layout. Right-click on each slide, choose Format Background, choose the image to use, and apply it to that slide.
(If you’re using Google Slides as a PowerPoint alternative, click on the Background button to accomplish the same thing.)
Images that are taller than they are wide may end up being stretched out of proportion, which ruins the effect. So in that case, try centering them on blank slides and adding a drop shadow, from the options on the image formatting ribbon.
STEP 2: ADD CAPTIONS:
To add captions, click on the Shapes tool, choose a rectangle shape, and draw it on your slide. Double click in it to type onto the shape, and use your theme’s color options to change the background and text color of the shape.