机器之心·2025-05-16 04:39Core Viewpoint - Google has launched LightLab, a project that allows precise control over lighting in images, enabling users to adjust light source intensity, color, and insert virtual light sources into scenes [1][2]. Group 1: Technology and Methodology - LightLab utilizes a fine-tuned diffusion model trained on a specially constructed dataset to achieve precise control over lighting in images [7][11]. - The dataset combines real images with controlled lighting changes and synthetic images generated by a physical renderer, allowing the model to learn complex lighting effects [10]. - The model can simulate indirect lighting, shadows, and reflections, providing a photorealistic prior for lighting control [10][11]. Group 2: Data Collection and Processing - The research team captured 600 pairs of original photos depicting the same scene with a single light source turned on and off, ensuring good exposure through automatic settings [22][23]. - The dataset was expanded to approximately 36,000 images through post-processing to cover a range of intensities and colors [27]. - The team employed a consistent tone mapping strategy and separated target light source changes from ambient light in the images [17][18]. Group 3: Model Training and Evaluation - The model was trained for 45,000 steps at a resolution of 1024 × 1024, using a learning rate of 10−5 and a batch size of 128, taking about 12 hours on 64 v4 TPUs [28]. - Evaluation metrics included Peak Signal-to-Noise Ratio (PSNR) and Structural Similarity Index Measure (SSIM), with user studies conducted to validate results [29]. - The model demonstrated superior performance compared to previous methods, achieving a PSNR of 23.2 and an SSIM of 0.818 [31][33]. Group 4: Applications and Features - LightLab offers a range of lighting control features, allowing users to adjust light source intensity and color interactively [12][38][41]. - The technology enables the insertion of virtual point light sources into scenes, enhancing creative possibilities [44]. - The separation of target light sources from ambient light allows for control over natural light entering a scene, which is typically challenging to manage [45].