The file name is one of the most important factors when it comes to optimizing images for SEO. The image name should contain the main keyword, as it gives search engines their first clue about what the image contains. It should accurately describe the image content. For individual images, it's possible that the main keyword isn't used in the image name, but rather one of the secondary keywords. This is especially true if a URL contains multiple images on different aspects of a topic. Typically, however, images relate to the page's main keyword, as they graphically support the topic addressed in the URL.
Example:
One image shows an infographic intended to rank for the keyword "air-water japan phone number data heat pump." This means that the file "img65-5467.jpg" does not convey any content information to Google. However, if the file name is, for example, "air-water-heat pump.jpg," a thematically relevant keyword placement is immediately ensured. This makes it easier for the search engine to categorize the topic.
To understand images, Google considers not only the file name but also the URL path and thus the folder structure the image is located in. Therefore, images should be named and stored in such a way that a logical thematic structure emerges from the URL alone.
File name recommendations :
Short but descriptive file names should be used.
When naming the image file, only lowercase letters should be used.
Umlauts or language-specific special characters should be avoided, as otherwise some browsers and tools will not be able to process the names.
Hyphens should be used instead of underscores to separate words in URLs.
Spaces must not be used in the file name, as this can lead to crawling problems.
If special characters must be used, they should be encoded as UTF-8.
When localizing, translated file names should be used for images.
If there are thousands of images on a website, consider automated naming. The file name, like alt attributes, should then be automatically generated according to a predefined pattern.
When doing SEO for images, as with optimizing other content, a keyword analysis should first be carried out to determine the relevant main keywords with search volume.
