在Python中将所有RGB像素的亮度降低20％？

Question

I have been trying to teach myself more advanced methods in Python but can't seem to find anything similar to this problem to base my code off of.

First question: Is this only way to display an image in the terminal to install Pillow? I would prefer not to, as I'm trying to then teach what I learn to a very beginner student. My image.show() function doesn't do anything.

Second question: What is the best way to go about lowering the brightness of all RGB pixels in an image by 20%? What I have below doesn't do anything to the alter the brightness, but it also can compile completely. I would prefer the most simple way to go about this as far as importing minimal libraries.

Third Question: How do I made a new picture instead of changing the original? (IE- lower brightness 20%, "image-decreasedBrightness.jpg" is created from "image.jpg")

here is my code - sorry it isn't formatted correctly. Every time i tried to indent it would tab down to the tags bar.

import Image
import ImageEnhance

fileToBeOpened = raw_input("What is the file name? Include file type.")
image = Image.open(fileToBeOpened)

def decreaseBrightness(image):
    image.show()
    image = image.convert('L')
    brightness = ImageEnhance.Brightness(image) 
    image = brightness.enhance(20) 
    image.show() 
    return image

decreaseBrightness(image)

Answer 1

To save the image as a file, there's an example on the documentation:

from PIL import ImageFile

fp = open("lena.pgm", "rb")

p = ImageFile.Parser()

while 1:
    s = fp.read(1024)
    if not s:
        break
    p.feed(s)

im = p.close()

im.save("copy.jpg")

The key function is im.save .

For a more in-depth solution, get a nice beverage, find a comfortable place to sit and enjoy your read: Pillow 3.4.x Documentation .