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This project focuses on developing an automated system for replacing faces in photographs, revolutionizing the process currently done manually by graphic artists. Key components include face detection, head pose estimation, illumination extraction, facial expression synthesis, and merging/replacement algorithms. By considering light estimation, skin tone approximation, 3D model fitting, basis image generation, and color blending techniques, the system achieves realistic results. The system enables various applications in Hollywood special effects, personalized movies, and more. Further research areas include enhancing face detection and tracking for videos, improving expression synthesis, refining reflectance models, and advancing model-fitting accuracy.
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Digital Face Replacement in Photographs CSC2530F Project Presentation By: Shahzad Malik January 28, 2003
Face Replacement Motivation • Currently done manually by graphic artists using photo editing software • An automatic system has many potential uses: • Hollywood special effects • “Personalized” movies • Framing someone…
Required Components • Need the following subsystems: • Face detection (and tracking for videos) • Head pose estimator • Illumination extractor (*) • Facial expression synthesis • Merging/replacement algorithm (*)
Light Estimation • Assuming a Lambertian reflectance model: • Any image can then be represented by:
Approximate Skin Tone • Cannot assume 3 basis images for arbitrary photographs • Use an approximate image to generate basis
Fitting a Generic 3D Model • Need geometry to create basis images • Fit a generic 3D face mesh to images • “Lift” a texture using planar mapping
Generate Basis Images • Set 3 linearly independent light positions • Relight skin tone model with each light
Determining the Coefficients • Compute a least squares solution to: • Solve separately for each RGB channel
Re-illuminating the Target Face • Set intensities of the 3 light sources to the coefficient values • Render the target face with these lights
Flesh Pixel Detection • Match non-mesh skin pixels to new skin tone • Use a histogram-based skin classifier
Histogram Matching • Generate histograms for newly lit face • Match the Gaussian distribution from original face to newly lit face • For each flesh pixel in original image, choose a new color with a similar location on the Gaussian bell curve
Weighted Color Blending • Blend converted flesh pixels with face mesh pixels
Summary • Presented a face replacement system • Takes lighting and merging into account • Future research areas: • Face detection and tracking (for videos) • Expression synthesis • More sophisticated reflectance model • Automatic and precise model-fitting