I learned last week on the MediaWiki message board that several people have requested help with uploading images to MediaWiki.
When Ted designed our RoboHelp2Wiki extension he used a separate option to upload images primarily to save testing time and possible some bandwidth. I validated the separate option and was able to upload 500 test images (various sizes) in a few minutes. Your speed will vary!
1. Download the RoboHelp2Wiki MediaWiki extension
2. Make sure all images have unique names.
3. Place all image files in a single sub-directory under the working directory named images
4. At the command line type: java -jar RoboHelp2Wiki.jar <workingDirectory> image