Q: new mac mini - resolution problems when connecting full hdtv

Hello community!

I am puzzled on what to do about my issue with the resolution displaying on my full hdtv using as a monitor to my brand new mac mini. It is connected HDMI to HDMI to my philco LED full hdtv that is also brand new. The issue is the quality is absolutely terrible for image as everything is pixelated and details are lost. Text is also very difficult to read. I need this to work because I am doing a video editing project and the client needs it very soon, and I cannot do it on my macbook pro for the screen is just too small to do editing. I have tried to configure display options on the TV monitor from sharpness, contrast to brightness without any success. I have also gone into the mac options for display and changed from 1080p to 1080i with a little bit of improvement but all images are so pixelated and blurred that all detail is lost. I good example is on facebook the thumbnail of someones profile picture looks like colorful blurred image and you can maybe make out its a persons face. So... I write my friend who is a tech and had sold me the hdtv about my issue, he mentioned it is most likely the HDMI cable is bad quality and apparently it is difficult to find here (Argentina) where I am good quality. So I need someone to please help me and explain to me what could be done besides buying another HDMI cable? by the way the cable I bought was in a walmart and I was told it was a high speed, good quality when purchased. not sure what to think now!?

many thanks

-Suzy in Argentina