Фильтр поиска чёрного цвета работает, но после добавления строк для увеличения контрастности появилась ошибка

import cv2 as cv2
import numpy as np
import skimage
import imutils
from imutils import contours
from skimage import measure
import argparse
import array

image = cv2.imread('1.jpeg',0)
cv2.imshow("tests", image)
cv2.waitKey()

theta = 1
phi = 1
maxIntensity = 255.0
# Decrease intensity such that
# dark pixels become much darker,
# bright pixels become slightly dark
newImage1 = (maxIntensity/phi)*(image/(maxIntensity/theta))**2
newImage1 = np.array(newImage1, dtype=np.uint8)
cv2.imshow("tests", newImage1)
cv2.waitKey()
blur = cv2.GaussianBlur(newImage1, (7,7), 0)
hsv = cv2.cvtColor(blur, cv2.COLOR_BGR2HSV)
mask = cv2.inRange(hsv, (0,0,0), (179,50,55))
cv2.imshow("tests", mask)
#cv2.waitKey()

kernel = cv2.getStructuringElement(cv2.MORPH_ELLIPSE, (7,7))
opening = cv2.morphologyEx(mask, cv2.MORPH_OPEN, kernel, iterations=1)
cv2.imshow("tests", opening)
cv2.waitKey()
close = cv2.morphologyEx(opening, cv2.MORPH_CLOSE, kernel, iterations=2)
cv2.imshow("tests", close)
cv2.waitKey()
cnts,_ = cv2.findContours(close, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)

for c in cnts:
    approx = cv2.approxPolyDP(c, 0.04 * cv2.arcLength(c, True), True)
    area = cv2.contourArea(c)
    if len(approx) > 3 and area > 200:
        cv2.drawContours(image, [c], -1, (0,255,0), -1)

cv2.imshow('image', image)
if cv2.waitKey(0):
    cv2.destroyAllWindows()

    hsv = cv2.cvtColor(blur, cv2.COLOR_BGR2HSV)
cv2.error: OpenCV(4.5.3) c:\users\runneradmin\appdata\local\temp\pip-req-build-sn_xpupm\opencv\modules\imgproc\src\color.simd_helpers.hpp:92: error: (-2:Unspecified error) in function '__cdecl cv::impl::`anonymous-namespace'::CvtHelper<struct cv::impl::`anonymous namespace'::Set<3,4,-1>,struct cv::impl::A0x2f9e5da8::Set<3,-1,-1>,struct cv::impl::A0x2f9e5da8::Set<0,5,-1>,2>::CvtHelper(const class cv::_InputArray &,const class cv::_OutputArray &,int)'
> Invalid number of channels in input image:
>     'VScn::contains(scn)'
> where
>     'scn' is 1