Problems with Photo Animation HD when compress to MPEG-2 for DVD

Hi, I made a documentary 30 min lenght. This doc has just 2 photo animated (simulating a pan) moving right to left pretty slow.

When I did the Master in ProRes HQ, It looks perfect, but when I compressed this Master to make a SD DVD using Media Encoder, all video looked great, excepted these two photo animations, than looks awful. I have tried for a week all the posible options to fix it: pixels aspect ratio, compression max quality, fields, photoshop setting for animation, resize, add a bit of blur, and so on,...but I couldn't fix it. I spoke with some people and some of then told me this is a problem about  down scale from HD to SD,  DVDs reduce the resolution to almost a quarter of the original size 1920 to 720, so some artifacting is going to occur.

I wonder if somebody here kenos something about it or found a solution about this problem ?

I'll appreciate any comment about it.Thanks !!