Fast screenshot of a small part of the screen in Python-CodePudding

I am currently working on a project where I need to take a 30x40 pixels screenshot from a specific area of my screen. This is not very hard to do as there are plenty of methods that do that.

The issue I have is that I need to take about 10 to 15 screenshots/second of the size I mentioned. When I looked at some of these methods that capture the screen, I have seen that when you give them parameters for a smaller selection, there's cropping involved. So a full screenshot is being taken, then the method crops it to the given size. That seems like a waste of resources if I'm only going to use 30x40 image, especially considering I will take thousands of screenshots.

So my question is: Is there a method that ONLY captures a part of the screen without capturing the whole screen cutting the desired section out of the big screenshot? I'm currently using this command:

im = pyautogui.screenshot(region=(0,0, 30, 40)).

CodePudding user response：

The Python mss module ( https://github.com/BoboTiG/python-mss , https://python-mss.readthedocs.io/examples.html ), an ultra fast cross-platform multiple screenshots module in pure Python using ctypes ( where MSS stands for Multiple Screen Shots ), is what you are looking for. The screenshots are fast enough to capture frames from a video and the smaller the part of the screen to grab the faster the capture (so there is apparently no cropping involved ). Check it out. mss.mss().grab() outperforms by far PIL.ImageGrab.grab(). Below a code example showing how to get the data of the screenshot pixels (allows to detect changes):

import mss
from time import perf_counter as T
left  = 0
right = 2
top   = 0
btm   = 2 

with mss.mss() as sct:
    # parameter for sct.grab() can be: 
    monitor = sct.monitors[1]         # entire screen
    bbox    = (left, top, right, btm) # screen part to capture

    sT=T()
    sct_im = sct.grab(bbox) # type: <class 'mss.screenshot.ScreenShot'>
    eT=T();print(" >", eT-sT) #  > 0.0003100260073551908

    print(len(sct_im.raw), sct_im.raw) 
    # 16 bytearray(b'-12\xff\x02DU\xff-12\xff"S_\xff')
    
    print(len(sct_im.rgb), sct_im.rgb) 
    # 12 b'21-UD\x0221-_S"'