Page dewarp

• Faster version of page_dewarp in C++.
• A dockerized test environment is available.
• [Update: 2021-06-15]
  • CLI options(contributed by zvezdochiot) added as in section 5.
  • Supports parallel processing.

1. Requirements

• Opencv 4.0 or greater.

• g++ 9.3 or greater.

2. Compile

• Pull the docker image

# host shell
docker pull stnamjef/opencv-4.0.0:1.0

• Run the docker image

# pwd -> a host directory containing all the sources(.h, .cpp)
docker run -it -v $(pwd):/source stnamjef/opencv-4.0.0:1.0

• Compile

# container shell
g++ -o page_dewarp main.cpp -std=c++17 -pthread $(pkg-config --cflags --libs opencv4)

3. Run

• Run page_dewarp.
• Warning: an input directory(-idir) must be given. Please check the CLI options below.

# container shell
./page_dewarp -idir=./test_images

4. Example

5. CLI options

Options	dtype	description
-idir	string	Input directory containing images to process (default=NONE).
-odir	string	Output directory where dewarped images should be saved (default=./dewarped).
-nw	integer	The number of workers(threads) for parallel processing (default=1). It is not recommended to set this option greater than the number of CPU cores.
-it	string	Input image type(default=text). It must be either "text" or "table".
-mx	integer	Reduced pixel to ignore near L/R edge of an image(default=50).
-my	integer	Reduced pixel to ignore near T/B edge of an image(default=20).
-m	integer	Reduced pixel to ignore near L/R/T/B edge of an image.
-z	float	How much to zoom output relative to the original image(default=1.0).
-d	integer	Just affects stated DPI of PNG, not appearance(default=300).
-r	integer	Downscaling factor for remapping an image(default=16).
-tw	integer	Min reduced pixel width of detected text contour(default=15).
-th	integer	Min reduced pixel height of detected text contour(default=2).
-t	integer	Min reduced pixel width and height of detected text contour.
-ta	float	Min text w/h ratio; Text contours below this value will be filtered out(default=1.5).
-tt	integer	Max reduced pixel thickness of detected text contour(default=10).
-eo	float	Max reduced pixel horizontal overlap of contours in span(default=1.0).
-el	float	Max reduced pixel length of edge connecting contours(default=100.0).
-ea	float	Cost of an angles in edges(default=10.0).
-em	float	Max change in angle allowed between contours(default=7.5).
-sw	integer	Min reduced pixel width for span(default=30).
-sp	integer	Reduced pixel spacing for sampling along spans(default=20).
-fl	float	Normalized focal length of camera(default=1.2).
-ro		Remap only (no threshold).
-db		Debug mode (default=0).