defisheye

Python scripts for unwarping the images produced by a fisheye lens.

Code is adapted from Kenneth Jiang from this Medium article, which can be referenced for a more in-depth explanation.

Example

Input

Output

Setup

Install pip packages

python3 -m venv env; source env/bin/activate
pip install -r requirements.txt

Calibrate to your specific fisheye lens

Every lens is different so we must calibrate our program to our lens.

To obtain the proper calibration settings for our lens, we must:

• Print this checkerboard image on regular sized printer paper.
• Stick the checkerboard image we just printed onto a flat surface. A clipboard, or in my case, a shoebox works fine. The key here is the checkerboard must be flat.
• Capture photos of the printed checkerboard from multiple angles using our fisheye lens. We should take photos from as many angles as possible. 30+ photos from different angles will suffice.
• Replace the photos in the photos directory with the photos captured in the previous step. These should be png or jpg format.

Then to obtain our calibration settings (saved to calibrate_config.py):

python calibrate.py

Remove fisheye distortion

# Remove fisheye and resize image to fit original image size (black around edge is cropped)
python defisheye.py input.jpg

# Remove fisheye and keep entire image
python defisheye_retain_all.py input.jpg

The balance value [0, 1.0] used in defisheye_retain_all.py can be modified to crop more or less of the black around the edge of the undistorted image. For example balance=0.0 will produce cropped output with no black edges while balance=1.0 will produce uncropped output. By default, balance is set to 1.0.