无法在python 3.6.5中打开.png文件

Question

我试图理解一个pygame代码，但我无法在我的计算机上运行它。我在python中非常新。出错的代码部分就在这里..

from pygame.locals import *
from random import randint
import pygame
import time

class App:

windowWidth = 800
windowHeight = 600
player = 0
apple = 0

def __init__(self):
    self._running = True
    self._display_surf = None
    self._image_surf = None
    self._apple_surf = None
    self.game = Game()
    self.player = Player(5) 
    self.apple = Apple(8,5)
    self.computer = Computer(5)

def on_init(self):
    pygame.init()
    self._display_surf = pygame.display.set_mode((self.windowWidth,self.windowHeight), pygame.HWSURFACE)

    pygame.display.set_caption('Pygame pythonspot.com example')
    self._running = True
    self._image_surf = pygame.image.load("pygame.png").convert()
    self._apple_surf = pygame.image.load("apple.png").convert()
if __name__ == "__main__" :
    theApp = App()
    theApp.on_execute()

错误信息与此完全相同......

RESTART: C:/Users/Dipto/AppData/Local/Programs/Python/Python36/gametest1.py 
Traceback (most recent call last):
File "C:/Users/Dipto/AppData/Local/Programs/Python/Python36/gametest1.py", 
line 263, in <module>
theApp.on_execute()
File "C:/Users/Dipto/AppData/Local/Programs/Python/Python36/gametest1.py", 
line 233, in on_execute
if self.on_init() == False:
File "C:/Users/Dipto/AppData/Local/Programs/Python/Python36/gametest1.py", 
line 185, in on_init
self._image_surf = pygame.image.load("pygame.png").convert()
pygame.error: Couldn't open pygame.png