Creating Rewrite Rule

I have a Apache Webser and want to deliver WebP over a Script. the script generates from .png and .jpg a .webP if needet. i have startet to write a rewrite rool who does not work: 1. Checking if browser supports WebP 2. Check if File is jpg oder png 3. rewrite all Images in 2 subfolders (Does not Work) Example: /webptest/[login to view URL] --> /webp/[login to view URL] Example: /webptest2/[login to view URL] --> /webp/[login to view URL] ### WEBP RewriteEngine On Options +FollowSymlinks RewriteCond %{HTTP_ACCEPT} image/webp RewriteCond %{REQUEST_URI} (?i)(.*)(\.jpe?g|\.png)$ RewriteRule ^webptest/(.*)\.jpg?$ /webp/[login to view URL]$[login to view URL] [QSA]