To make an image transparent in PowerPoint, you have to change the opacity of the image - and you can do it for the whole image or a part.

You can make a picture transparent in your PowerPoint slides so that you can add text over it or use it as a background.

After making the image a bit transparent, you’re ready to add the lines that create the collage effect. How to insert lines to create a collage effect in PowerPoint ...

To add alt text to images in PowerPoint, or edit an image's existing alt text, select the photo and choose "Edit Alt Text." ...

If you don’t want the same rectangular pictures for your Microsoft PowerPoint slide show, create a custom-shaped picture placeholder and make it available to the presentation via a layout slide.