First of all, beware at this: when you reduce image dimension (e.g. from full resolution of your dSLR to 720 pixel), you ALWAYS loss sharpness. So, you ALWAYS have to sharpen your reduced images. Returning to your problem, you probably use full resolution images in your PTE project. But, when PTE create the DCD, it probably reduces images dimension to DVD standard (I don't remember exact number, but it is close to 700x500, as ft1805 said). So, images loss sharpness. In order to avoid this, you have to reduce image dimension to DVD standard, apply correct shapen on them and finally use these reduced images in PTE project.