Picture quality testing method and apparatus for color cathode-ray tube

A method of testing the quality of a picture displayed on a color cathode-ray tube, comprising the steps of:

• displaying a white raster on a phosphor screen of the color cathode-ray tube to be tested and deriving color image data from the phosphor screen;
• subjecting said color image data to chromaticity transformation for obtaining a chromaticity image including chromaticity image data;
• extracting a selected nonuniform color portion from said chromaticity image;
• calculating the average chromaticity, area and edge intensity of said extracted nonuniform color portion for calculating quantities of features of said nonuniform color portion;
• and
• calculating an evaluated value of white uniformity on the basis of said feature quantities.

An apparatus for testing the quality of a picture displayed on a color cathode-ray tube, comprising:

• a color television camera for picking up an image of white color displayed on said color cathode-ray tube;
• means for separating color signals from an output signal of said color television camera;
• means for converting said separated color signals into digital color signals;
• memory means for storing said digital color signals;
• and
• a computer for analyzing the contents of said memory means, said computer including means for extracting a nonuniform color portion from a color distribution of the display on said color cathode-ray tube, means for calculating quantities of features of said extracted nonuniform color portion, and means for calculating an evaluated value of white uniformity on the basis of said calculated feature quantities.