Most 3 megapixel cameras produce photos that are 2048 x 1536.
That is more than enough pixels to produce a good image on your television.
First check and make sure that your files are approximately 2048 x 1536.
If they are, I would suspect the software you are using to produce the DVD.
Or the method the DVD info gets to the Television.
How are you producing the DVD?
What are you using to send the DVD info to the television?
For this purpose, I use a DVD slide show program to produce the DVD.
And use a standard set-top DVD player to play the DVD and show it on television.
I get good results with photo files as small as 1 megapixel.
I am now burning my photos to DVD to view on my TV,,,my Canon camera has 3.1 megapixels. Most of the 4x6 and up to 8x10 prints are acceptable. However, when viewed on the TV they are not very sharp, in fact most are fuzzy. Do I need to get a new camera with more megapixels?