Unfortunately, there's nothing you can do to restore the original picture from the emailed versions. Depending on the software and/or email program you're using, it's probably resized the image to lower resolution, which is NOT the same as compression. Also, JPEG is what's known as "lossy compression", which means it makes images smaller by discarding some of the image data, and once that data is gone, it's gone.
Your only hope is that you still have the unaltered originals on your computer - again depending on the software (I'm not familiar with Picture Manager), the resized version that's emailed may be a new copy and the original is still intact.