Why it gives me a black image and libpng warning: iCCP

[rickyw2777]

This is my code:

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from picamera2 import Picamera2 import cv2 import numpy as np import time import math import argparse import RPi.GPIO as GPIO GPIO.setmode(GPIO.BOARD) PWM_pin   = 32   #Define pin, frequency and duty cycle freq      = 50 dutyCycle = 7.5 #90 degrees at first#                 #Values 0 - 100 (represents 4%, ~27 deg) minv=20 maxv=48 angles=[90] width=1000 height=1333 rect1=(0,654)  rect2=(1000,1005) x1s=[] x2s=[] y1s=[] y2s=[] x3s=[] y3s=[] GPIO.setup(PWM_pin, GPIO.OUT) # Create PWM instance for pin w freqency pwm = GPIO.PWM(PWM_pin, freq) # picam2 = Picamera2()    parser=argparse.ArgumentParser(description="lower and upper bound for trying") parser.add_argument('--tim',default=2,help="length of time to run") parser.add_argument('--delay',default=1,help="time between image captures") parser.add_argument('--debug',action='store_true',default=True,help="debug mode") args=parser.parse_args()   def get_duty(angle1,angle2):     duty1=(1/18)*angle1 +2.2     duty2=duty1+0.4*(angle2-angle1)*(1/18)     return duty2   def get_points(img,debug):           if img is None:         print("Error: Unable to load image.")         exit()       height, width = (img.shape[:2])           def blank(x):  # Null function for trackbar         pass                 mask = np.zeros(img.shape[:2], dtype=np.uint8)     mask = cv2.rectangle(mask,rect1,rect2, 255, -1)     masked_img = cv2.bitwise_and(img, img, mask=mask)           img=masked_img     img =cv2.GaussianBlur(img, (3, 3), 0)     edge = cv2.Canny(img, minv, maxv)     lines = cv2.HoughLinesP(edge, 1, np.pi / 180, threshold=100, minLineLength=20, maxLineGap=10)       output = img.copy()  # Avoid modifying the original image     if lines is not None:  # Check if lines were detected         for i in range(len(lines)):             for x1, y1, x2, y2 in lines[i]:                 cv2.line(output, (x1, y1), (x2, y2), (0, 255, 0), 2)                 print(f'x1:{x1:0.2f}\ty1:{y1:0.2f}\tx2:{x2:0.2f}\ty2:{y2:0.2f}')                 x1s.append(x1)                 x2s.append(x1)                 y1s.append(y1)                 y2s.append(y2)                 with open('data.txt', 'a') as f:                     f.write(f'{x1:0.2f}\t{y1:0.2f}\t{x2:0.2f}\t{y2:0.2f}')                     f.write('\n')       if debug== True:         # cv2.imshow('image', img)         # cv2.imshow('mask', mask)         # cv2.imshow('masked_image', masked_img)         cv2.imshow("houghline", output)         cv2.waitKey(5000)         cv2.destroyAllWindows()                          # picam2.stop()     return x1s,x2s,y1s,y2s       def get_angle(x1s,x2s,y1s,y2s):     pass                               start_time = time.time() cur_time   = start_time mesg_time  = start_time  i=0 while (start_time + args.tim > cur_time):         time.sleep(0.001)                 cur_time = time.time() # some short delay to avoid busy waits     if (mesg_time + args.delay < cur_time):         i+=1         time_1=time.time()         mesg_time = cur_time         # picam2.start()         img = cv2.imread("hallway.jpg") #take picture into memory         height, width = img.shape[:2]         scale = 0.5         new_size  = (int(height*scale), int(width*scale))         small_img = cv2.resize(img, new_size, interpolation=cv2.INTER_LINEAR)         #å ˆä¸ç¼©å°         # img_RAM_BGR= cv2.cvtColor(img_RAM,cv2.COLOR_RGB2BGR) #change color         #from RGB to BGR         debug=args.debug         # if debug == True:             # cv2.imshow("picture",img_RAM_BGR)             # cv2.waitKey(1000)             # cv2.destroyAllWindows()         # else:             # pass         # img_test = cv2.imread("bluetape.jpg")         x1s,x2s,y1s,y2s=get_points(small_img,debug) #call function         if debug == True:             time_2=time.time()             print(f'{time_2-time_1:0.2f}') #print the time it taken to complete the finding angle process         angle=get_angle(x1s,x2s,y1s,y2s) #         # dutyCycle=get_duty(angle1,angle2) #         # pwm.ChangeDutyCycle(dutyCycle) #         # if debug ==True:             # print(f'PWM:{dutyCycle}')         # else:             # pass

Here is the error:

/home/ricky/Desktop/lab_deliverable/lab6/hallway.py:26: RuntimeWarning: This channel is already in use, continuing anyway. Use GPIO.setwarnings(False) to disable warnings.
GPIO.setup(PWM_pin, GPIO.OUT) # Create PWM instance for pin w freqency
QStandardPaths: wrong permissions on runtime directory /run/user/1000, 0770 instead of 0700
libpng warning: iCCP: known incorrect sRGB profile
libpng warning: iCCP: known incorrect sRGB profile
libpng warning: iCCP: known incorrect sRGB profile
libpng warning: iCCP: known incorrect sRGB profile
libpng warning: iCCP: known incorrect sRGB profile
6.66
0.26

the error happened when I added these lines:

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scale = 0.5 new_size  = (int(height*scale), int(width*scale)) small_img = cv2.resize(img, new_size, interpolation=cv2.INTER_LINEAR)

[rickyw2777]

Problem Solve, I accidentally give the wrong coordinates for the resize function and the rectangle mask function

1 2	new_size  = (int(width*scale), int(height*scale))     img = cv2.resize(img, new_size, interpolation=cv2.INTER_LINEAR)

Notice how that it is width in the first place and height in the second.

and

1	mask = cv2.rectangle(mask,rect1,rect2, 255, -1)

The rect1 and rect2 represents the upper-left and bottom-right coordinates and they should be updated accordingly since the image ins resized as 0.25 times big.