Method and apparatus for automatically calibrating a CRT display

A calibration apparatus for calibrating a display driven CRT monitor, comprising:

• a single light sensor attached to a faceplate of the monitor;
• a single channel light meter connected to said sensor;
• and
• a computer connected to the monitor and said meter, said computer comprising:
• means for varying actual input codes provided to the monitor for each channel of the monitor and measuring actual responses of the monitor to the varying input codes;
• means for normalizing the actual responses to an aim highlight;
• means for smoothing the normalized responses and converting the smoothed normalized responses to negative log intensity values;
• means for producing aim tone scale intensities for possible image code values;
• means for searching the negative log intensity values for closest matches to the tone scale intensities;
• and
• means for creating a table of actual input code values for each possible image code value where closest matches between the negative log intensity values and aim tone scale intensities exist.

A method of calibrating a CRT monitor light source using a predetermined target scale curve, comprising the steps of:

• (a) measuring actual responses of the light source to image input values including normalizing the actual responses with respect to a monitor aim highlight said monitor having a wider dynamic range than said input image values and said normalizing step normalizes the highlight at less than a maximum output of the monitor;
• (b) mapping the image input values through the target tone scale curve into desired response values;
• (c) mapping the desired response values through the actual responses into calibrated input values;
• and
• (d) storing the calibrated input values in a look-up table having the image input values as indices into the look-up table.

A method of calibrating a CRT monitor light source, comprising the steps of:

• (a) measuring actual responses of the light source to image input values including measuring actual intensity responses to corresponding actual input values applied to the monitor and subtracting a cross talk correction value from the actual response;
• (b) mapping the image input values through a target tone scale curve into desired response values including obtaining a scale intensity from a tone scale table for an index input value;
• (c) mapping the desired response values through the actual responses into calibrated input values, including:
• (i) searching the actual intensity responses for a closest match between the scale intensity and the actual intensity response, and
• (ii) designating the corresponding actual input value of the closest match as the calibrated input value having the index input value, so that when an image is to be reproduced on the monitor image index input values of the image are converted into calibrated input values supplied to the monitor
• (d) storing the calibrated input values in a look-up table having the image input values as indices into the look-up table.