#!/usr/local/bin/python3
import io
import math
import sys
import numpy as np
from PIL import Image
def JPEGSaveWithTargetSize(im, filename, target):
"""Save the image as JPEG with the given name at best quality that makes less than "target" bytes"""
# Min and Max quality
Qmin, Qmax = 25, 96
# Highest acceptable quality found
Qacc = -1
while Qmin <= Qmax:
m = math.floor((Qmin + Qmax) / 2)
# Encode into memory and get size
buffer = io.BytesIO()
im.save(buffer, format="JPEG", quality=m)
s = buffer.getbuffer().nbytes
if s <= target:
Qacc = m
Qmin = m + 1
elif s > target:
Qmax = m - 1
# Write to disk at the defined quality
if Qacc > -1:
im.save(filename, format="JPEG", quality=Qacc)
else:
print("ERROR: No acceptble quality factor found", file=sys.stderr)
################################################################################
# main
################################################################################
# Load sample image
im = Image.open('/Users/mark/sample/images/lena.png')
# Save at best quality under 100,000 bytes
JPEGSaveWithTargetSize(im, "result.jpg", 100000)
如果按原样运行,目标大小为100000字节,则会得到:
-rw-r r @ 1 mark staff 96835 11 Sep 18:21 result.jpg
如果我将目标大小更改为50000字节,我会得到:
-rw-r r @ 1 mark staff 49532 11 Sep 18:26 result.jpg
我仍在学习Python,所以可能有更好的方法,但这里有一个函数,可以将PIL/枕头图像保存为JPEG格式,并允许您指定最大大小
它使用二进制搜索来最小化所需的工作量,并将其编码到
BytesIO
内存缓冲区以将写入的图像保存到磁盘。如果有人对改进有任何建议,请告诉我如果按原样运行,目标大小为100000字节,则会得到:
如果我将目标大小更改为50000字节,我会得到:
关键词:Python、PIL、枕头、JPEG、质量、质量设置、最大大小、最大大小、图像、图像处理、二进制搜索
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