Goal

The goal is to extract values from heatmap, given the legend color bar and legend min and max values.

This code was written because this didn't work.

Installation

Seems like colormath doesn't work with newer versions of numpy, so an older version of numpy needs to be used, which means older version of opencv-python needs to be used, which doesn't run well of Python 3.8+...

This is the setup in which the code works:

• Use python 3.6.X
• Upgrade pip using pip install --upgrade pip.
• Install packages with pip install -r requirements.txt

Getting the results

An image like this is expected:

We need to manually extract some information from it:

• (x_start, y_start) and (x_end, y_end) - top left and bottom right positions of the heatmap
• n and m - number of rows and columns in the heatmap
• x_legend - the x coordinate of the legend bar
• y_legend_bottom and y_legend_top - y range of the legend bar
• legend_min and legend_max - range for legend values
• number_of_legend_steps - how many values to extract from the legend

To get these values, you can run preview_image.py. The image will be shown and you can hover above it to identify all the necessary coordinates. Or you can use some other tool to do this.

Fill those values into extract_values script and run it. At the end, the extracted values will be shown on the image and printed in the terminal.