1. Generally, the picture frame should be covered with cardboard to set off the painting. If there are photos in it, you don't need to mount cardboard, just put the photos directly. However, there is a kind of rounded Chinese frame that is not suitable for holding photos.
2. photo Frame: (frame), which is similar to a square, with an empty inside and just a common photo in the blank. It is mainly used to locate the four sides of a photo and enhance its aesthetics. It is also beneficial to protect the quality of photos, such as photo frames with glass, which can prevent photos from changing color and yellowing. It's a decorative object hollowed out.