As part of a good SEO strategy it is recommended to carefully choose the filenames of images embedded in a website.
In addition, Typo3 does a really good job in resizing your images to resize your images to the required dimensions for the presentation on your site.
Unfortunately, by default Typo3 renames your image files when they are resized and stored in the temporary directory /typo3temp/pics/.
The renaming is based in a calculated hash value and it is required to prevent images from overriding each other. As a result your orginally named image interesting-image.jpg ends up in something such as 12h342k268.jpg which is useless for search engine optimization.
To solve this problem, you can configure Typo3 to use up to a certrain number of characters of the original filename as a prefix of the filename before setting the hash.
To do this, add the following line to the setup section of you template:
# prevent up to 100 characters of the original filename
# if an image is resized by typo3 and stored in /typo3temp/pics
config.meaningfulTempFilePrefix = 100
And empty the cache of your site.
As a result the resized copy of your file interesting-image.jpg will now be named interesting-image-12h342k268.jpg which is much more use ful than the hash code only before.