peicheng

How to compress PDF using ghostscript

As a developer, it bothers me when someone sends me a large pdf file compared to the number of pages. Recently, I recieved a 12MB scanned document for just one letter-sized page... so I got to googlin, like I usually do, and found ghostscript!

to learn more abot ghostscript (gs): https://www.ghostscript.com/

What we are interested in, is the gs command line tool, which provides many options for manipulating PDF, but we are interested in compressign those large PDF's into small yet legible documents.

credit goes to this answer on askubuntu forum: https://askubuntu.com/questions/3382/reduce-filesize-of-a-scanned-pdf/3387#3387?newreg=bceddef8bc334e5b88bbfd17a6e7c4f9

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Permalink: git.io/vps

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2023 update

ℹ️ Please note this research is from 2016 when Opera has first added their browser "VPN", even before the "Chinese deal" was closed. They have since introduced some real VPN apps but this below is not about them.

🕵️ Some folks also like to use this article to show a proof that the Opera browser is a spyware or that Opera sells all your data to 3rd parties or something like that. This article here doesn't say anything like that.

When setting up (that's immediately when user enables it in settings) Opera VPN sends few API requests to https://api.surfeasy.com to obtain credentials and proxy IPs, see below, also see The Oprah Proxy.

The browser then talks to a proxy de0.opera-proxy.net (when VPN location is set to Germany), it's IP address can only be resolved from within Opera when VPN is on, it's 185.108.219.42 (or similar, see below). It's an HTTP/S proxy which requires auth.

steps:

you need to have node.js installed
copy main.js & package.json to a new folder
in the terminal:
- to build it, run: npm install and then npm start
- to pack it like a regular app, use 'electron-packager'. install it globally by running: npm install electron-packager -g

	# extraction pattern: ngram TAB year TAB match_count TAB volume_count NEWLINE
	# out: unique_ngram TAB sum(match_count) NEWLINE

	import re
	import os, sys, mmap
	from pathlib import Path
	from tqdm import tqdm
	from concurrent.futures import ThreadPoolExecutor

	abv = re.compile(r'^(([A-Z]\.){1,})(_\|[^\w])') # A.B.C.

	#!/usr/bin/env python
	"""Find the longest repeated substring.
	"Efficient way to find longest duplicate string for Python (From Programming Pearls)"
	http://stackoverflow.com/questions/13560037/

	The algorithm is based on "Prefix doubling".
	The worst time complexity is O(n (log n)^2). Memory requirements are linear.
	"""

	import time

	var queryParams = window.location.search.substr(1).split('&').reduce(function (qs, query) {
	var chunks = query.split('=');
	var key = chunks[0];
	var value = decodeURIComponent(chunks[1] \|\| '');
	var valueLower = value.trim().toLowerCase();
	if (valueLower === 'true' \|\| value === 'false') {
	value = Boolean(value);
	} else if (!isNaN(Number(value))) {
	value = Number(value);
	}

	package main

	import (
	"database/sql"
	"strconv"
	"log"
	"net/http"
	"fmt"
	"bytes"
	"gopkg.in/gin-gonic/gin.v1"

	def sort_bucket(s, bucket, order):
	d = defaultdict(list)
	for i in bucket:
	key = s[i:i+order]
	d[key].append(i)
	result = []
	for k,v in sorted(d.iteritems()):
	if len(v) > 1:
	result += sort_bucket(s, v, order*2)
	else:

	#!/usr/bin/env python
	import time
	import base64
	import hashlib
	import urllib
	import urlparse
	import urllib2
	import subprocess
	from collections import OrderedDict