Computer Vision Tricks with OpenCV and Other Computer Vision Libraries

Projects

• qrcode_science: Detect QR codes with OpenCV erosion and dilations
• polygon_science: Mask regions in a certain HSV color range and calculate polygons with OpenCV and Shapely

Color Space

To find a color in HSV see the colorspace plot below. In OpenCV hue (H) is in the range 0-179, saturation (S) 0-255 and value (V) 0-255. In the plot below, V is set to a constant value of 255.

See hsv_colorspace_plotter.py to see how this image was made with the matplotlib library.

Helper scripts

To explore interactively upper and lower values for the HSV values (the hue, saturation and value), the app/tool color_thresholder.py may be used on an image (check the script to set the input image).

To determine upper and lower values for colors using RGB values, the find_hsv_ranges.py will provide this (check the script to set input RGB values).

To explore HSV masks and image results try out explore_hsv_masks.py (check the script to set the input image - right now it's set for two red ranges).