В чем ошибка с функцией cv2.imshow?

Хочу сделать свою функцию inRange, которая позволяла бы в hsv_max кидать значения, меньшие, чем в hsv_min. Зачем это нужно, рассказано здесь.
код:

import cv2
import numpy as np

def my_inRange(img_hsv, hsv_max, hsv_min):
    img_h = np.shape(img_hsv)[0]
    img_w = np.shape(img_hsv)[1]
    img_result = np.array([[255 for i in range(img_w)] for j in range(img_h)])
    for i in range(img_h):
        for j in range(img_w):
            now_hsv = img_hsv[i, j]
            for n in range(3):
                if hsv_max[n] > hsv_min[n]:
                    if now_hsv[n] < hsv_min[n] or now_hsv[n] >= hsv_max[n]:
                        img_result[i, j] = 0
                        break
                else:
                    if now_hsv[n] < hsv_min[n] and now_hsv[n] >= hsv_max[n]:
                        img_result[i, j] = 0
                        break
    return img_result

def nothing(*arg):
    pass

cv2.namedWindow("result")
cv2.namedWindow("pic")
cv2.namedWindow("settings")

img = cv2.imread("roof.png")

cv2.createTrackbar('h1', 'settings', 0, 255, nothing)
cv2.createTrackbar('s1', 'settings', 0, 255, nothing)
cv2.createTrackbar('v1', 'settings', 0, 255, nothing)
cv2.createTrackbar('h2', 'settings', 255, 255, nothing)
cv2.createTrackbar('s2', 'settings', 255, 255, nothing)
cv2.createTrackbar('v2', 'settings', 255, 255, nothing)

while True:
    hsv = cv2.cvtColor(img, cv2.COLOR_BGR2HSV)
    h1 = cv2.getTrackbarPos('h1', 'settings')
    s1 = cv2.getTrackbarPos('s1', 'settings')
    v1 = cv2.getTrackbarPos('v1', 'settings')
    h2 = cv2.getTrackbarPos('h2', 'settings')
    s2 = cv2.getTrackbarPos('s2', 'settings')
    v2 = cv2.getTrackbarPos('v2', 'settings')

    h_min = np.array((h1, s1, v1), np.uint8)
    h_max = np.array((h2, s2, v2), np.uint8)

    thresh = my_inRange(hsv, h_min, h_max)

    cv2.imshow('result', thresh)
    cv2.imshow('pic', img)

    ch = cv2.waitKey(5)
    if ch == 27:
        break
print(type(img))
cv2.destroyAllWindows()

выдает ошибку

Traceback (most recent call last):
  File "D:/.../final6_podbor_1.py", line 52, in <module>
    cv2.imshow('result', thresh)
cv2.error: OpenCV(4.0.0) c:\projects\opencv-python\opencv\modules\imgproc\src\color.hpp:261: error: (-2:Unspecified error) in function '__cdecl cv::CvtHelper<struct cv::Set<1,-1,-1>,struct cv::Set<3,4,-1>,struct cv::Set<0,2,5>,2>::CvtHelper(const class cv::_InputArray &,const class cv::_OutputArray &,int)'
> Unsupported depth of input image:
>     'VDepth::contains(depth)'
> where
>     'depth' is 4 (CV_32S)

Что сделать, чтобы все заработало?