Rotate JPG images losslessly using the EXIF orientation tag

最新推荐文章于 2023-06-22 22:32:43 发布

原创最新推荐文章于 2023-06-22 22:32:43 发布 · 101 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#IDEA #F# #HTML

Android 专栏收录该内容

112 篇文章

订阅专栏

本文介绍了一种现代数码相机能够感应拍摄时相机方向的技术，并详细解释了如何利用EXIF数据中的“Orientation Tag”来实现图片的智能无损旋转。文章还提供了一个具体的例子，展示了如何使用ABC-View Manager软件来实现这一功能。

http://www.abc-view.com/articles/article5.html

A great idea from one of our users made into reality!

Some modern digital cameras now sense the orientation of the camera at the moment of capture.

This information is stored in the EXIF data, using the "Orientation Tag". ABC-View Manager is able to display this information, use Item -> Properties and then click the Tags tab.

The orientation tag can have 8 different values, presenting 8 different kinds of orientation that a picture can have.

Note that only some models of modern digital cameras support this option.

These are the values that can be present in the orientation tag. For a technical background, please refer to the excellent description on jpegclub.org .

Value	0th Row	0th Column
1	top	left side
2	top	right side
3	bottom	right side
4	bottom	left side
5	left side	top
6	right side	top
7	right side	bottom
8	left side	bottom

Here is another description given by Adam M. Costello:

For convenience, here is what the letter F would look like if it were tagged correctly and displayed by a program that ignores the orientation tag:


  1        2       3       4         5            6           7          8

888888  888888      88  88      8888888888  88                  88  8888888888
88          88      88  88      88  88      88  88          88  88      88  88
8888      8888    8888  8888    88          8888888888  8888888888          88
88          88      88  88
88          88  888888  888888

ABC-View Manager is now able to use this information and perform a lossless rotation or flipping action on your images, smartly using this value.

How to do it?

Select some images, using [Ctrl] or [Shift] for multiple. You can select all files with [Ctrl-A]. Then select:

Tools -> Lossless -> Rotate using EXIF flag

Notice that you can exactly see what ABC-View Manager is going to do with each file. The column "Exif Orientation Flag" shows the value of the EXIF flag, and "Action" shows what kind of operation will be done on the file.

When the file is rotated or flipped, a value of 1 will be substituted in the EXIF field, to signal that the rotation is completed. This will avoid doing the operation accidentally twice.

ABC-View Manager also keeps the file date of the file intact.