You don't say which version of the program you're using, but versions 8 and 9 include a Share option for outputting stills in a variety of formats.
Just go to Share/Computer/Still Image.
All of these outputs, however, use non-square pixels so, unless you go to the Advanced settings and set up the pictures for square pixels, they may look distorted when you output them.
In my books, I show you how to create a custom preset for outputting 640x480 square pixel JPEGs.
BTW, you can also of course use Photoshop Elements, if you have it, to convert your BMP into a JPEG.
You are correct about the file extension change from BMP to JPEG. BMP is basically uncompressed, and JPEG requires processing to achieve with the JPEG algorithm. They are not interchangeable.
Now, if one is going to use the image in a Video (or printing much above the physical pixel x pixel size), I am less a fan of JPEG compression. In my workflow, I would go from BMP to PSD (the native PS/PSE format), and not go with JPEG. Many editors do not see the compression issues with JPEG, that bother me so much. Just my personal choice.
In PS, it's easy to convert a folder of BMP's to PSD's with an Action and Automate to Batch. I think that PSE can do this, as well.
Thanks Hunt. Norman
You are most welcome, and hope that helps.
Steve, thanks for the reply. I have Photoshop Elements 7 and I did not see still image as an option. I also went to Muvipix site and did not find your preset. When I view the still image, it looks sharp, but if I double click on it, it becomes fuzzy and also when I export it to Photoshop Elements. Any help there? Norman