Have a look at my FAQ to the right of this forum.
As I explain in greater detail in my books, video is of a much lower resolution than most photos. So it doesn't matter how large the photo you drop into a video editor, you get roughly the equivalent of 640x480. That's video resolution. (If you're using hi-def, you get more -- but still nowhere near what you get in print photos.)
Using photos that are larger than 1000x750 pixels, then, not only overloads the program, but it's usually a waste of time too (since they take longer to render). You'll still only get 640x480 pixels (actually 720x480 non-square pixels) when it's converted to video.
Also remember to render your timeline (press Enter) every time you add a photo to it or there is a red line above your clips. When this red line turns green, you'll see a much better representation of what your final output will look like rather than a low-rez soft render.
Thank you Steve and Bill for your suggestions, but this is not the answer.I have been expiremting and i find if I import directly into Premiere Elements from Pictures I get the following message " This type of file is not supported or the required codec is missing ".If I click on ok the photos are imported at a poor quality, they are either in Jpeg or Tiff format, which must be ok but what is "the required Codec" and can you suggest how I can rectify the problem ?.
I'm not sure how you're doing what you're doing, but photos don't have codecs so, unless you've somehow convinced the program that you're actually importing video, there's no reason you should see that message.
Meantime, remember, as we've said, that any photos that you load into a video will appear at essentially 640x480 pixels -- greatly reduced from what you'd use for, say, printing. You also should render your timeline (by pressing Enter) so that the red lines above any clips on your timeline turn green in order to see these photos at full quality.
Finally, don't presume that what you're seeing in the Monitor panel is what your final video will look like! It, too, has quality settings -- and it is only a preview of your final video.
Follow our instructions and you'll get the best possible quality.