Hi

So long as the photos are of greater resolution then the finished DVD or BD, then there should be no problem with image quality.

However I find that I get the best results with images resized as follows:-

DVD widescreen   -  1600 x 900 or 3200 x 1800 px  -  see note below

HD widescreen PAL 1080i  -  3840 x 2160 px (this also happens to be the resolution of still images taken with my video camera) or at a push 1920 x 1080 px

Note if you have Photoshop or any other image editting software that lets you export images with the pixels stretched in the horizontal direction for widescreen then in theory I would use 1440 x 1152 px images - however I have never found this necessary.

Depending on the images they may also benefit from sharpening as they will lose a little when the video is rendered.  You may need to experiment with this.

HTH

John