Patent ID: 6927882

Claim:
A method of producing a light source compensating element for an image reading apparatus, the image reading apparatus including a light-radiating device for emitting an illuminating light to a scanned object, said method comprising: providing a target film and a characteristic curve of said target film, said characteristic curve shows transmittance of said target film after being exposed versus light brightness exposing said target film; determining a required transmittance distribution on said target film in accordance with a first brightness distribution and a second brightness distribution; wherein said first brightness distribution is the brightness distribution of the illuminating light projected directly from the light-radiating device onto the scanned object, and said second brightness distribution is a predetermined brightness distribution desired to be formed onto the scanned object; exposing said target film by a light source with adjustable brightness, wherein the brightness of said light source is adjusted with reference to said characteristic curve to expose said target film, so that said target film have said required transmittance distribution; and developing said target film to form said light source compensating element.