# Edge Detection Example

# Original Sketch from Processing's Topics/ImageProcessing/EdgeDetection Example code

#

# In this adaptation of Processing's Edge Detection example, OpenCV is used to

# perform the edge detection. The edge detection mode can be changed by pressing

# 't' for tight, 'w' for wide, or any other key for auto.

#

# Canny edge detection algorithm adapted from:

# https://pyimagesearch.com/2015/04/06/zero-parameter-automatic-canny-edge-detection-with-python-and-opencv/

import traceback

import numpy as np

import cv2

from jpype import JClass

import py5_tools

import py5

def filter_image(img: py5.Py5Image, img_filtered: py5.Py5Image, mode: str):

try:

img.load_np_pixels()

if mode == 'auto':

sigma = 0.33

median = np.median(img.np_pixels)

lower_limit = int(max(0, (1 - sigma) * median))

upper_limit = int(min(255, (1 + sigma) * median))

elif mode == 'tight':

lower_limit, upper_limit = 225, 250

elif mode == 'wide':

lower_limit, upper_limit = 10, 200

img_array_gray = cv2.cvtColor(img.np_pixels, cv2.COLOR_BGR2GRAY)

img_array_blurred = cv2.GaussianBlur(img_array_gray, (5, 5), 0)

img_array_edges = cv2.Canny(

img_array_blurred, lower_limit, upper_limit)

img_filtered.set_np_pixels(img_array_edges, bands='L')

except Exception as e:

traceback.print_exc()

return JClass('java.lang.RuntimeException')(str(e))

py5_tools.register_processing_mode_key("filter_image", filter_image)

# run the sketch in processing mode, specifying the Java class to instantiate

py5.run_sketch(jclassname='test.Example4Sketch')