Patent ID: 8469482

Claim:
A method for determining a variance of a sensor in inkjet printers comprising: maintaining a printer carriage at a stationary position; illuminating a media patch of known characteristics with a light source that varies an intensity of the light between at least a first and second intensity, in which the second intensity is different from the first intensity; obtaining at least specular reflectance data from light reflected off the media patch by measuring a signal from a photo-detector during the illumination; and comparing the specular data to stored values to determine a variation of the sensor response for forming a correction factor; using the correction factor to calibrate at least a first signal of the inkjet printer; obtaining diffuse reflectance and comparing the diffuse data to stored values to determine a variation of the sensor response for forming a correction factor; using the correction factor to calibrate at least a second signal of the inkjet printer; and using the calibrated signal to execute a scan for media edge detection.