ROBUST THRESHOLDING BASED ON WAVELETS AND THINNING ALGORITHMS FOR DEGRADED CAMERA IMAGES C

This paper describes a thresholding method for degraded docu- ments acquired from a low-resolution camera. This technique is based on wavelet denoising and global thresholding for non- uniform illumination. The accent is put on stroke analysis to keep useful information more accurately without breaking cha- racters and by reducing the number of overconnected ones. An improvement of the technique, which uses the thinning algo- rithm, is thus detailed and a particular attention is given to use this optimization in the convenient images only. Moreover, thanks to the wavelet decomposition, complex backgrounds as well as high frequency noise can be considered. This method can handle various corpus of images without need of any prior knowledge of the document image and fine-tuning of parame- ters.