This paper researches the difference between tracepro simulation and human eyes observation in uniformity of LCD TV direct backlight. In order to make the simulation result reflects the true situation

the data simulated by tracepro was put into the formula that adapt to the human eyes observation

the Weber coefficient of each sampling point was calculated. Comparing with the visions Weber coefficient 0.017

it is determined whether or not there will be nonuniformity

then re-fitting the new graph of backlight uniformity. This can help the designer evaluate the product better in design step.