How to Apply Background Patterns to Collage

On the top Collage menu, click Background button and then the background dialog box pops up.

Color fill: In the background dialog box, you can select Color Fill to make an artistic background, the background pattern format can be set as Solid Fill, Gradient (Top to Bottom), Gradient (Left to Right).

Image fill: Select Image Fill to the set background, drag the slider to choose one background you like, there are ways to display the image background: Tile, Center, Stretch, Stretch Crop, you can preview the image background on the right part of dialog.