1. Optimization-based Image Decolorization Why Grayscale Image? Student Name: XU Zhinan Advisor: Professor Chiew-Lan Tai a)Widely used in pattern recognition & image processing b) Small scale of data & simple to code c) Monochrome printing

2. Previous Work [Neumann et al. 2007] [Gooch et al. 2005] [Grundland et al. 2007] CIE Y

3. Local contrast [Kim et al. 2009] Disadvantage: Global contrast is ignored. Advantages: Global mapping Local contrast preserving Conversion: (Lch to grayscale) Objective Function:

4. Global contrast—Lch & RGB Input LchRGBKim et al. CIE Y Global contrast: statistics in CIE Lch

5. Global contrast—Gaussian Pairing Input Kim et al. Gaussian Displacement vector:

6. Optimization-based Image Decolorization