The following are some useful picture material websites: 1. Pixabay: It has more than 4.5 million high-quality pictures and video materials, allowing you to easily deal with various design scenarios.

2. Photo Network: Provides a collection of hand-drawn illustrations, posters, ppt templates, technology, cities, business, architecture, scenery, food, home, exteriors, backgrounds and other beautiful picture design materials for download.

3. Nitu.com: Provides massive original materials, picture downloads, photography works, design materials, video materials, ppt templates, PSD source files, vector graphics, AI, CDR, EPS and other high-definition picture downloads.