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visualize_annotations.py
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[Usage]: python3 visualize_annotations.py --img_dir image_dir --math_dir math_dir --out_dir output_dir --char_dir char_dir

"visualize_annotations.py": visualize math regions and character regions on images. 

This script takes 3 or 4 parameters.
<image_dir>: directory path containing 600 DPI images.
<math_dir>: directory path containing annotations for math regions (".math files")
<output_dir>: directory path to store rendered images for corresponding PDF files.
<char_dir>: directory path containing annotations for character regions (".char files")

<char_dir> is optional parameter. 
<math_dir> is optional parameter.
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