this is to creata a pad around the image if the crop bbox is less than the origin or grater than the image width and height.

create_pad_for_crop_img.py

import cv2

def pad_img_to_fit_bbox(img, x1, x2, y1, y2):
    img = cv2.copyMakeBorder(img, - min(0, y1), max(y2 - img.shape[0], 0),
                            -min(0, x1), max(x2 - img.shape[1], 0),cv2.BORDER_REPLICATE)
    y2 += -min(0, y1)
    y1 += -min(0, y1)
    x2 += -min(0, x1)
    x1 += -min(0, x1)
    return img, x1, x2, y1, y2

def imcrop(img, bbox):
   x1, y1, x2, y2 = bbox
   if x1 < 0 or y1 < 0 or x2 > img.shape[1] or y2 > img.shape[0]:
        img, x1, x2, y1, y2 = pad_img_to_fit_bbox(img, x1, x2, y1, y2)
   return img[y1:y2, x1:x2, :]

im = cv2.imread("image/acc1.png")
bbox = -1,-299,200,100
crop_img = imcrop(im,bbox)
cv2.imshow("Img", crop_img)
cv2.waitKey(0)
cv2.destroyAllWindows()