Text Line Dewarping

Dependencies

pip3 install -r requirements.txt

NOTE: If you are using pyenv to install older versions of Python, you might need to install development versions of libsqlite3x, ncurses, readline, and tkinter. For example, on Fedora: dnf install libsq3-devel ncurses-devel readline-devel tk-devel.

Running

To process the entire image

Run the dewarp.py script :

python ./dewarp.py ./sample.png ./output.png

To process the image only where there's text

Run the tight_dewarp.py script :

python ./tight_dewarp.py ./sample.png ./output.png

Both functions exhibit comparable performance, with no discernible advantage in either. The primary distinction lies in their operational scope: dewarp.py operates across the entire image, whereas tight_dewarp.py specifically tracks the leftmost and rightmost black pixels within Otsu's threshold image, concentrating its efforts within that identified range.

Steps

1. Load Image :

2. Convert from RGB to Grayscale :

3. Apply Otsu's Thresholding Method, Erosion and then Dilation :

4. Calculate curve using Generalized Additive Model :

5. Final Image :

Greek Text Example

1. Input Image :

2. Output Image :

Rectification

1. Input Image :

2. Semi-processed Image :

3. Output Image :

The rectification dataset can be viewed and downloaded through this link.

Citation

If you have found value in this repository, we kindly request that you consider citing it as a source of reference:

Stogiannopoulos, Thomas. “Curved Line Text Alignment: A Function That Takes as Input a Cropped Text Line Image, and Outputs the Dewarped Image.” GitHub, December 1, 2022. https://github.com/TomStog/curved-text-alignment.