1. material websites: There are many websites that provide free or paid material downloads, such as Pexels, Unsplash, Pixabay, etc. All kinds of high-quality photos, textures, backgrounds and other materials can be searched on these websites.

2. Social media platforms: On social media platforms such as Instagram and Pinterest, many photographers or artists will share their photos and works. You can search for keywords or browse the accounts of relevant photographers to find materials suitable for the later stage of Cos photography.

3. Photographer cooperation: If you know or know some photographers, you can ask them for photos or cooperate with them and use their photos as post-production materials. You can contact photographers through email, social media or their personal websites.

4. Shoot by yourself: If you have photographic equipment, you can also take photos by yourself as post-production material. You can find suitable models, scenes, costumes and take photos according to your own needs.

It should be noted that when using other people's photos as post-materials, you should abide by the copyright law and relevant laws and regulations to ensure that you are legally authorized or use free materials. In addition, when using the material, we should pay attention to the consistency with the theme and the matching of tone and style, so as to make the post-processing more harmonious and natural.