This article introduces the key technologies behind the popular Mia鸭 Camera on WeChat Moments. Firstly, it utilizes the diffusion model technology behind AI-generated paintings. The diffusion model gradually adds noise to the original data and then reverses the process to generate new samples, capable of producing high-quality, diverse data. The article further explores the theoretical background, basic principles, and applications of the diffusion model, which is widely used in image generation, such as Stable Diffusion, DALLE·2, and Midjourney, resulting in high-quality, realistic photos generated by Mia鸭 Camera. Overall, Mia鸭 Camera employs the diffusion model technology to achieve high-quality image generation.