# Hough Transform Example:
#
# This example demonstrates using the Hough transform to find lines in an image.
import sensor, image, time

kernel_size = 1 # kernel width = (size*2)+1, kernel height = (size*2)+1
kernel = [-1, -1, -1,\
          -1, +8, -1,\
          -1, -1, -1]
          
# This is a high pass filter kernel. see here for more kernels:
# http://www.fmwconcepts.com/imagemagick/digital_image_filtering.pdf
thresholds = [(200, 255)] # grayscale thresholds

sensor.reset() # Initialize the camera sensor.
sensor.set_pixformat(sensor.GRAYSCALE) # or sensor.RGB565
sensor.set_framesize(sensor.QQVGA) # or sensor.QVGA (or others)
sensor.skip_frames(30) # Let new settings take affect.
clock = time.clock() # Tracks FPS.

# On the OV7725 sensor, edge detection can be enhanced
# significantly by setting the sharpness/edge registers.
# Note: This will be implemented as a function later.
if (sensor.get_id() == sensor.OV7725):
    sensor.__write_reg(0xAC, 0xDF)
    sensor.__write_reg(0x8F, 0xFF)

while(True):
    clock.tick() # Track elapsed milliseconds between snapshots().
    sensor.set_pixformat(sensor.GRAYSCALE)
    img = sensor.snapshot() # Take a picture and return the image.

    img.morph(kernel_size, kernel)
    img.binary(thresholds)

    # Erode pixels with less than 2 neighbors using a 3x3 image kernel
    img.erode(1, threshold = 2)
    img.draw_rectangle((0, 0, 160, 120), color=0x00)
    
    # Find lines.
    lines = img.find_lines(threshold=40)
    # Switch back to RGB to draw red lines.
    sensor.set_pixformat(sensor.RGB565) # or sensor.RGB565
    img = sensor.snapshot()
    for l in lines:
        img.draw_line(l, color=(0xFF, 0x00, 0x00))

    print(clock.fps()) # Note: Your OpenMV Cam runs about half as fast while
    img = sensor.snapshot() # Take a picture and return the image.

Add Hough Transform example script.
Add Hough Transform example script.
