Working with EXIF-data in jpg, png, and webp files

Details: Category: Servers; Published: Thursday, 10 December 2020 16:03; Written by Super User; Hits: 1439

Almost all image files have the ability to store additional data, such as image size, creation time, geo-coordinates and so on.

It is also possible to add additional parameters - description, copyright and more.

There are EXIF data

Exchangeable image file format - a standard that defines the format of the description of auxiliary meta-information for image and sound files and used by digital cameras (including those in smartphones), scanners and other systems.

By the way, there is insufficient evidence that search engines use exif-image data on sites to rank the site and search optimizing.

Now let's see how to add or change EXIF-data

Metadata in jpg and png files

For these purposes, Linux has an exiftool utility that can output or modify metadata in png and jpg files.

To install it, you need to execute a command

apt install libimage-exiftool-perl

When executing a command

exiftool image.jpg

will display the current information that is stored in this file, something like

ExifTool Version Number : 10.80

File Name : image.jpg

Directory : .

File Size : 156 kB

MIME Type : image/jpeg

Exif Byte Order : Little-endian (Intel, II)

Creator Tool : Adobe Photoshop CC 2014 (Windows)

Profile CMM Type : Linotronic

Color Transform : YCbCr

Image Width : 580

Image Height : 400

Bits Per Sample : 8

Color Components : 3

Y Cb Cr Sub Sampling : YCbCr4:4:4 (1 1)

Image Size : 580x400

Megapixels : 0.232

this is only part of the output, because the full output is too long.

If we want to add or change a certain field (in our case - ImageDescription), we will do it with the command

exiftool -ImageDescription="My best image" image.jpg

Similarly, you can change or add any other field, such as copyright

If you want to clear the metadata, you can run

exiftool -all=  image.jpg

To delete a specific field
exiftool -ImageDescription=  image.jpg
More precisely, in this way we do not delete the field itself, but simply delete the data in it.

Metadata in webp files

The exiftool utility does not yet support webp files and we need another utility to work with them - webpmux

To install it, execute the command

apt install webp

This utility is not able to display metadata, but only saves them in the specified file

webpmux -get exif image.webp -o image_metadata.exif

If an error occurs while executing this command, it means that there are no metadata in the file

To set the data we need in a webp file, we first need to create a metadata file (such as file.exif) and write something like

Author: Yakim

After that, execute the command

webpmux -set exif file.exif image.webp -o image.webp

Note that the source file has the ability not to change, but to create a new one and already add metadata there.