Can you provide a little more information? What format is the signal from your cameras? What format are you recording in? What are you recording on? What format are you sending through the RG6 cable-SD or HD? Analog or digital? How are you delivering to the cable system?
BE aware that the cable company is going to further compress your video when it's inserted into their system. Depending on that amount of compression, it can have a huge affect on the look of the delivered video. Grass, leaves or running water have a large amount of detail information which is often lost during compression. When it goes into the cable system it will be compressed again resulting in mush when the video has a lot of detail.