Abstract: In measuring the dots of a color picture tube panel the panel is scanned and energy passing through the dots is detected. A large number of lines are scanned and the scan data are stored in a matrix having a row for each scan line and, columns for the dots and the spaces between the dots. Data for a preselected number of dots and spaces are stored. When scanning occurs between rows of dots, the preselected number of dots is not scanned and zeros are put into the matrix. Data processing is simplified by searching the last column of the matrix for zeros and rejecting all rows of data having a zero in that column.