Are you keying in the destination file name manually and forgetting to type .gif on the end? That seems to have been an issue with someone that I googled. Otherwise just google for solutions, it's a mediawiki error.
Many images on SWC (ships, vehicles, etc.) are shown as png format but are actually jpegs. Or the contrary.
Sometimes it happens also with images taken from the web.
The easiest solution is to change the extension (Windows) or use a software like FastStone Image Viewer, open the image, check the info (right side of the screen) and save the image as, with the format updated according to its type.
Mediawiki is more stringent with image data, this is why it happens.
EDIT: When I tried to upload the image, I didn't get the MIME type error. Rather, I got this one:
Error creating thumbnail: sh: /usr/bin/convert: No such file or directory
Probably it needs a thumbnail then?
Anyway, your image is in this page now: http://holocron.swcombine.com/wiki/CorSec#Holographics
Edited By: Ruben Wan on Year 17 Day 293 14:11 ____________
Yes, I was not negative on the graphics formats or the art team, and if I have sounded so I apologise.
In Neria's case, the problem was due to how photobucket.com treats the links. It adds an .html extension even for the direct link, so you must find a workaround to display the image. My first attempt at saving the image resulted in an empty file (0kb).