Here is a tip how you easily can convert all your BF tga screenshots into png's so they can be used in galleries and such...(and best of all - you keep maintain the quality...)

If you haven't got it...download Irfanview free of charge of course..
http://www.irfanview.com/
"one of the most popular viewers worldwide!"

Install without toolbar (uncheck checkbox)(it's only added to support the browser instead of funds)
When done open a picture in your screenshot directory

Irfanview starts and you press "B" or "file/batch conversion/rename"
A new dialog shows up and you press "ALT+D" or "Add all"
This selects all your screenshots at once and adds them into the textbox below.
In the batch conversion settings you change image format to "PNG - Portable Network Graphics"
Output directory can be same as screenshots so we use "Current or press "ALT+U"

And finally we click on "Start Batch" and go grab a cup of coffe..it could take time depending on the # of screenshots and your computer...

Here is a screenshot of mine