This guide briefly describes what image metadata is , the type of metadata, and how to find and view image metadata in the Linux operating system.

Table of contents

• 1. Technical metadata
• 2. Descriptive metadata
• 3. Manage metadata
• View image metadata on Linux
  • 1. Using ImageMagick
  • 2. Use file command
  • 3. Using Exif
  • 4. Using ExifTool
• Summarize

What is image metadata?

Image metadata is a set of information about an image. Metadata is either embedded in the image itself or stored in a separate file.

There are three types of metadata:

1. Technical metadata,
2. descriptive metadata,
3. Manage metadata.

1. Technical metadata

As the name implies, technical metadata usually contains technical information about images.

Technical metadata includes camera details, DPI, shutter speed, file size, image format, date and time to take or create an image, software used to create an image, and some other details.

Technical metadata is mainly automatically generated by camera devices.

2. Descriptive metadata

Descriptive metadata is added manually by the photographer. The owner (or photographer) can add it manually using any external software, such as GIMP or Photoshop.

It contains information such as photo title, location, photographer name and comments. Descriptive metadata is useful for easy and quick searches for photos.

3. Manage metadata

Administrative metadata contains the owner's identity and contact information, license, copyright and terms of use.

Adding metadata to images is important to prevent content theft, abuse, and tracking the use of images. However, metadata is easily stripped. Hope you understand the basic concepts of image metadata and its types.

Now let's continue to see how to find information about images on the command line in Linux.

View image metadata on Linux

There are many tools on Linux to find the metadata of images. Here, I provide four command line tools to view these details.

1. Use ImageMagick

ImageMagick has a command line tool called "Identify" to find image metadata. ImageMagick is available in the default repository for most Linux distributions.

On Arch Linux and its variants, run the following command to install ImageMagick:

 <code>$ sudo pacman -S imagemagick</code>

On Debian, Ubuntu, Linux Mint:

 <code>$ sudo apt install imagemagick</code>

On Fedora:

 <code>$ sudo dnf install imagemagick</code>

On SUSE/openSUSE:

 <code>$ sudo zypper install ImageMagick</code>

Now let's look for the image metadata. To do this, just run:

 <code>$ identify -verbose image.png</code>

This command lists the detailed output of the given image metadata.

(The long output example of the identifier command is omitted here because this part of the content does not match the pseudo-original goal and is too long)

If you only need basic details, just delete the -verbose option.

 <code><strong>$ identify image.png</strong></code>

More details can be found in the man page:

 <code>$ man identify</code>

2. Use the file command

We can use the file command (used to determine file type) to view the metadata of the image.

 <code><strong>$ file image.png</strong></code>

The file command does not provide detailed output options like the "identify" command. It prints only the basic metadata.

Read the man page to learn more about file commands:

 <code>$ man file</code>

3. Use Exif

Exif is a command line utility that displays and changes EXIF ??data for images.

For those who want to know, EXIF ??(representing the interchangeable image file format) is usually a JPEG file that is written to the storage device every time you take a picture with your smartphone or camera.

EXIF data includes details such as the date and time of the photo, camera settings, geographic location, license and copyright information.

Exif is available in the default repository of Debian and its derivatives such as Ubuntu.

 <code>$ sudo apt install exif</code>

To view image metadata using exif, just run:

 <code>$ exif image.jpg</code>

Exif will generate a nice output in table column format. (The output example of the exif command is omitted here, the reason is the same as above)

Exif not only reads metadata, but also writes EXIF ??to the image. For more details, see the man page:

 <code>$ man exif</code>

4. Use ExifTool

ExifTool is another command line tool for viewing and managing image metadata information. Compared to all the other utilities above, ExifTool is a rather advanced and feature-rich application that supports multiple file formats.

ExifTool allows you to view, edit, and write metadata in a variety of file formats, including image, audio and video files. It is especially useful for handling EXIF, IPTC, and XMP metadata (usually used in digital photography).

With ExifTool, you can perform various tasks such as:

1. Read and display metadata : ExifTool can extract and display metadata in files, including camera settings, GPS coordinates, etc.
2. Edit Metadata : You can use ExifTool to add, modify, or delete metadata tags in files.
3. Write metadata : ExifTool can write metadata to a file, allowing you to add or update information such as titles, keywords, or copyright notices.
4. Batch processing : ExifTool supports batch processing, allowing you to easily perform operations on multiple files simultaneously.

(The detailed introduction of ExifTool is omitted here, because this part of the content does not match the pseudo-original goal and is too long to link to related documents)

Summarize

In this guide, we learned what image metadata is and its types. We also discussed how to find metadata for images in Linux using ImageMagick, file commands, and Exif tools.

(The recommended reading part is omitted here, for the same reason as above)

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