JPEGclub.org develops new JPEG features and maintains the Independent JPEG Group's (IJG) software. The current version is release 9c of 14-Jan-2018. It is the only true source reference JPEG codec.
Exif Orientation Page - JPEGclub.org
Read this table as follows (thanks to Peter Nielsen for clarifying this - see also below): Entry #6 in the table says that the 0th row in the stored image is the right side of the captured scene, and the 0th column in the stored image is the top side of the captured scene.. Here is another description given by Adam M. Costello:
IJG - Independent JPEG Group
Independent JPEG Group IJG is an informal group that writes and distributes a widely used free library for JPEG image compression. The first version was released on 7-Oct-1991.
libjpeg - Wikipedia
libjpeg is a free library with functions for handling the JPEG image data format. It implements a JPEG codec (encoding and decoding) alongside various utilities for handling JPEG data. It is written in C and distributed as free software together with its source code under the terms of a custom permissive (BSD-like) free software license, which demands attribution.
E-cutter--オールフリーソフト Windows 7・8・10対応のフリーソフト--
オールフリーソフトは最新のWindows OSで使えるフリーソフトを紹介します。 オールフリーソフト(トップ)→画像→画像合成・分割・切り取り→E-cutter
JPEG Autorotate - Apps - Olli Savolainen
JPEG Autorotate Windows 10, 8, 7, Vista, XP, 2000 . Ever had the problem of pictures taken in portrait showing up in landscape in emails, on your blog or on your mobile device?
JPEG画像を簡単に無劣化で切り抜き・回転できるフリーソフト「JPEGcrop」 - GIGAZINE
JPEG画像を簡単に無劣化で切り抜き・回転できるフリーソフト「JPEGcrop」 by Blu* JPEG画像を無劣化のまま扱い、左右反転・上下反転・90度回転・180度 ...