如何将OpenCV（cv2）图像（BGR和BGRA）转换为pygame.Surface对象 [英] How do I convert an OpenCV (cv2) image (BGR and BGRA) to a pygame.Surface object

问题描述

我从

 导入pygame 
导入cv2 
 
 def cv2ImageToSurface（cv2Image）：
如果cv2Image.dtype.name =='uint16'：
 cv2Image =（cv2Image / 256）.astype（'uint8'）
 size = cv2Image.shape [1 ::-1] 
 format ='RGBA'if cv2Image.shape [2] == 4 else'RGB'
 cv2Image [:,：，[0，2]] = cv2Image [:,： ，[2，0]] 
 surface = pygame.image.frombuffer（cv2Image.tostring（），大小，格式）
返回surface.convert_alpha（ ）如果format =='RGBA'else surface.convert（）
 
 pygame.init（）
 window = pygame.display.set_mode（（300，300））
 clock = pygame.time.Clock（）
 
 cv2ImageJPG = cv2.imread（'woodtiles.jpg'，cv2.IMREAD_UNCHANGED）
 cv2ImagePNG = cv2.imread（'apple.png'，cv2。 IMREAD_UNCHANGED）
 pygameSurfaceJpg = cv2ImageToSurface（cv2ImageJPG）
 pygameSurfacePng = cv2ImageToSurface（cv2ImagePNG）
 
 run =真实
运行时：
 clock.tick（60） pygame.event.get（）中事件的
：如果event.type == pygame.QUIT：
：
 run = False 
 
 window.fill（0） 
 window.blit（pygameSurfaceJpg，pygameSurfaceJpg.get_rect（center = window.get_rect（）。center））
 window.blit（pygameSurfacePng，pygameSurfacePng.get_rect（center = window.get_rect（）。center）） 
 pygame.display.flip（）
  

I created images from OpenCV/opencv-python (numpy.array) and I want to convert them to a pygame.Surface object:

def cv2ImageToSurface(cv2Image):

    pygameSurface = # ? create from "cv2Image"

    return pygameSurface 

surface = cv2ImageToSurface(cv2Image)

Some of the images have 3 channels (BGR) and some of the images also have an alpha channel (BGRA). What do I have to do in cv2ImageToSurface to convert images with one of the formats into a pygame.Surface object?

解决方案

The shape attribute of a numpy.array is the number of elements in each dimension. The first element is the height, the second the width and the third the number of channels.
A pygame.Surface can be generated by pygame.image.frombuffer. The 1st argument can be a numpy.array and the 2nd argument is the format (RGB or RGBA).

Get the size (widht, height) for the pygame.Surface object by slicing:

size = cv2Image.shape[1::-1]

Determine the target format for the pygame.Surface object, depending on the third channel:

format = 'RGBA' if cv2Image.shape[2] == 4 else 'RGB'

Since the source format is BGR or BGRA, but the target format is RGB or RGBA, the red and blue channels have to be swapped:

cv2Image[:, :, [0, 2]] = cv2Image[:, :, [2, 0]]

With his data the pygame.Surface object can be generated by pygame.image.frombuffer`:

surface = pygame.image.frombuffer(cv2Image.tostring(), size, format)

To ensure that the image has the same pixel format as the display Surface and for optimal performance, the Surface should be converted with either convert or convert_alpha:

surface = surface.convert_alpha() if format == 'RGBA' else surface.convert()

Complete function cv2ImageToSurface:

def cv2ImageToSurface(cv2Image):
    if cv2Image.dtype.name == 'uint16':
        cv2Image = (cv2Image / 256).astype('uint8')
    size = cv2Image.shape[1::-1]
    format = 'RGBA' if cv2Image.shape[2] == 4 else 'RGB'
    cv2Image[:, :, [0, 2]] = cv2Image[:, :, [2, 0]]
    surface = pygame.image.frombuffer(cv2Image.tostring(), size, format)
    return surface.convert_alpha() if format == 'RGBA' else surface.convert()

Minimal example:

import pygame
import cv2

def cv2ImageToSurface(cv2Image):
    if cv2Image.dtype.name == 'uint16':
        cv2Image = (cv2Image / 256).astype('uint8')
    size = cv2Image.shape[1::-1]
    format = 'RGBA' if cv2Image.shape[2] == 4 else 'RGB'
    cv2Image[:, :, [0, 2]] = cv2Image[:, :, [2, 0]]
    surface = pygame.image.frombuffer(cv2Image.tostring(), size, format)
    return surface.convert_alpha() if format == 'RGBA' else surface.convert()

pygame.init()
window = pygame.display.set_mode((300, 300))
clock = pygame.time.Clock()

cv2ImageJPG = cv2.imread('woodtiles.jpg', cv2.IMREAD_UNCHANGED)
cv2ImagePNG = cv2.imread('apple.png', cv2.IMREAD_UNCHANGED)
pygameSurfaceJpg = cv2ImageToSurface(cv2ImageJPG)
pygameSurfacePng = cv2ImageToSurface(cv2ImagePNG)

run = True
while run:
    clock.tick(60)
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            run = False

    window.fill(0)
    window.blit(pygameSurfaceJpg, pygameSurfaceJpg.get_rect(center = window.get_rect().center))
    window.blit(pygameSurfacePng, pygameSurfacePng.get_rect(center = window.get_rect().center))
    pygame.display.flip()

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