If it didn't ever worked for any comic both in portrait and in landscape mode, I'd suggest to uninstall and install Komic again (using a newly downloaded package).
Please note:
- uninstalling Komic will delete the Gallery folder. If you want to keep it, just rename it before uninstalling Komic then rename it back to Gallery.
- you will lose your bookmarks
This is my last hope as I can't reproduce your problem and, moreover, the contrast/brightness box seems to work for others!
