I bought a Panasonic Progressive Plasma Display. It has 1 composite, 1 S-Video and 1 Component cable video input. I also have a digital cable box (Comcast) with just one video output (composite). Images from outdoors scenes with bright light or any channel presenting cartoons are too bright like hundreds of light bulbs are in the background. I figure that the quality of image that the composite cable is bringing to the TV is the cause (even though is a Monster cable). Am I right? If so, is it possible to "convert" the composite signal to component?
No, you are wrong. Even though cables can make a difference in quality, it won't be in brightness. It won't make the images brighter, low grade cables may make it fuzzy however. It's definitely possible to convert those. However, I don't think that will do you much good. I would suggest testing the output of your cable box on something else to see if it produces too much brights there. If it's fine, then there's something wrong with your TV.