For searching pixel errors, it is best just to fill the entire screen with one homogenous color. The TFT-Test
offers the colors white, red, green, blue and black. In case you recognize little dots on the area of the screen, it is most likely a pixel error. Before starting to search, it is recommended to clean the entire display so that there are no dust particles left which can be mistaken for a pixel error when they are reflecting light.
You can download the TFT-Test