scalebar - Processing tools for scale bars in images

Author: Dimitri Korsch

This package is meant to estimate the scale of a standardized scale bar in images captured by automatic light traps. An example of the visualization output can be seen below. The main function scalebar.get_scale outputs for a given image a float number representing the scale of the image in pixels per mm. This scale can later be used to estimate the size of the objects, insects, or animals in the picture.

Installation

python >= 3.7 required. Tested on Ubuntu 18.04 and Python v3.9 so far

With pip

pip install scalebar

From Source

git clone https://github.com/cvjena/scalebar
cd scalebar
# create a new environment, if you want (e.g. with conda create -n scalebar python~=3.9.0)
pip install -r requirements.txt

then either

make install

or

pip install .

or

python setup.py install

Usage

In your code

import cv2
import scalebar

im = cv2.imread(path_to_your_image)
px_per_mm = scalebar.get_scale(im, pos=scalebar.Position.top_left)
# process the scale as you want

From the console

python -m scalebar.estimate path/to/image.jpg
# outputs the scale to stdout
42.0

python -m scalebar.estimate path/to/image.jpg -o output.txt
# writes the scale to output.txt

# requires cvargparse, matplotlib, pyqt5
python -m scalebar.visualize path/to/image.jpg
# visualizes the estimation process

Licence

This work is licensed under a GNU Affero General Public License.