How to use the command 'exif' (with examples)

The exif command-line tool is designed to read, edit, and manipulate EXIF (Exchangeable Image File Format) data found within JPEG files. EXIF data contains valuable metadata such as camera settings, capturing device details, and even geographical location where the photo was taken. This makes the exif tool highly useful for photographers, digital asset managers, and anyone working with large collections of images.

In this article, we’ll explore various use cases of the exif command, each demonstrating how to display, extract, and modify EXIF data effectively.

Use case 1: Showing all recognized EXIF information in an image

Code:

exif path/to/image.jpg

Motivation:

Understanding the metadata associated with an image can provide comprehensive insights into the circumstances surrounding its capture. This might include details such as the brand and model of the camera used, the date and time the photo was taken, and various camera settings. For professionals managing large sets of images, quickly accessing this information is essential.

Explanation:

• exif: Invokes the exif command-line tool.
• path/to/image.jpg: The path to the image file from which you wish to extract the EXIF information.

Example Output:

Upon executing this command, you would see a display of the complete set of recognized EXIF information available within the image file. This output typically includes data such as Camera Model, Date and Time, Exposure Settings, etc.

Use case 2: Showing a table listing known EXIF tags and whether each exists in an image

Code:

exif --list-tags --no-fixup image.jpg

Motivation:

In scenarios where you want to quickly verify the presence of specific metadata tags within your image file, this command provides a clear checklist of what is available. Whether you’re tracking down missing metadata or ensuring compliance with metadata standards, this is a handy command to use.

Explanation:

• exif: Executes the exif tool.
• --list-tags: Lists all known EXIF tags.
• --no-fixup: Ensures that the command does not attempt to automatically correct any malformed EXIF data.
• image.jpg: The image file whose metadata tags are being queried.

Example Output:

This command produces a table with rows for each known EXIF tag and columns indicating their presence or absence in the particular image file, offering a straightforward way to review available metadata.

Use case 3: Extracting the image thumbnail into a separate file

Code:

exif --extract-thumbnail --output=thumbnail.jpg image.jpg

Motivation:

Images taken with digital cameras often include a small thumbnail preview in their EXIF data, which can be extracted and used for quick previews without loading the full-resolution image. This is particularly useful for web developers and software applications needing fast thumbnail previews.

Explanation:

• exif: Calls the exif command-tool.
• --extract-thumbnail: Option to extract the thumbnail embedded within the image’s EXIF data.
• --output=thumbnail.jpg: Specifies the file name for the extracted thumbnail.
• image.jpg: The JPEG file from which to extract the thumbnail.

Example Output:

Running this command will create a new file, thumbnail.jpg, containing the thumbnail image extracted from the original, allowing users to quickly utilize it as a preview.

Use case 4: Showing the raw contents of the “Model” tag in the given image

Code:

exif --ifd=0 --tag=Model --machine-readable image.jpg

Motivation:

For developers or data analysts who need raw, unformatted data from specific EXIF tags for processing or integration with other systems, this command provides a means to extract just that information. It is useful in scripting contexts where precise, standardized data output is necessary.

Explanation:

• exif: Initiates the EXIF tool interface.
• --ifd=0: The Image File Directory to use, typically containing primary image and camera configuration data.
• --tag=Model: Specifies the EXIF tag to read, in this case, the camera model.
• --machine-readable: Outputs the data in a format that is easily parsed by machines.
• image.jpg: The image from which to retrieve EXIF data.

Example Output:

This command outputs the model of the camera used to capture the image in a plain, easily processed text format, useful for automated systems or scripts.

Use case 5: Changing the value of the “Artist” tag to John Smith and saving to a new file

Code:

exif --output=new.jpg --ifd=0 --tag="Artist" --set-value="John Smith" --no-fixup image.jpg

Motivation:

Modifying the EXIF metadata to include authorship and ownership information is crucial for professionals who want to ensure proper attribution and copyright metadata within their image files. This capability allows users to standardize or batch-update metadata as needed.

Explanation:

• exif: Executes the exif tool.
• --output=new.jpg: Designates a new file name for the image after modification.
• --ifd=0: The Image File Directory, normally where the artist data is stored.
• --tag="Artist": Identifies the specific EXIF tag “Artist” to change.
• --set-value="John Smith": Assigns a new value to the specified tag.
• --no-fixup: Prevents automatic corrections to malformed data fields.
• image.jpg: The original image file to modify.

Example Output:

After executing, you will find a newly created JPEG file named new.jpg, in which the “Artist” tag within the EXIF data has been changed to “John Smith”.

Conclusion:

The exif command-line tool is an essential utility for managing and manipulating the metadata associated with JPEG files. From extracting complete metadata to updating specific data fields, each use case provides a powerful function, making exif an invaluable tool for photographers, digital asset managers, and data analysts alike. Its comprehensive feature set allows users to both view and modify EXIF data efficiently, enhancing the versatility and utility of their digital image libraries.