Granted Patent B2

US 7,564,601 · App. 11/550,537 · Granted Jul 21, 2009

Abstract

Claims (38)

1. A method for generating a tonal response curve for a scanner, comprising:

(a) directing light from said scanner to a calibration target having a single uniform neutral tone;

(b) measuring with said scanner an amount of incident light reflected from said calibration target to obtain a simulated optical density value associated with said calibration target and said amount of incident light;

(c) changing said amount of said incident light;

(d) repeating acts (b) and (c) until a predetermined number of simulated optical density values are accumulated; and

(e) generating said tonal response curve for said scanner by matching each of said simulated optical density values with one of a plurality of reference optical densities.

2. The method of claim 1 wherein said uniform neutral tone of said calibration target is any tone adhering to the equations luminance L*>TL and chrominance a*& b*<Tab as defined in CIELAB color space, where TL and Tab are predetermined thresholds.

3. The method of claim 1 wherein said changing said amount of said incident light is performed by changing a light intensity of said light output from said scanner.

4. The method of claim 1 wherein said scanner is incorporated into an imaging apparatus.

5. The method of claim 1 , further comprising scanning with said scanner a plurality of reference targets to generate said plurality of reference optical densities.

6. The method of claim 5 , further comprising storing in a memory first light intensity levels associated with said simulated optical density values and second light intensity levels associated with said plurality of reference optical densities.

7. The method of claim 6 , further comprising recalibrating said tonal response curve throughout a lifecycle of a device in which said tonal response curve is used based on said first light intensity levels and said second light intensity levels stored in said memory.

8. The method of claim 1 wherein said scanner is one of a plurality of scanners of a first type of scanners, and further comprising:

recording first light intensity levels used by said scanner in generating said simulated optical density values; and

using said first light intensity levels in another scanner of said first type for generating another tonal response curve corresponding to said another scanner.

9. The method of claim 8 , further comprising:

recording second light intensity levels used by said scanner in generating said plurality of reference optical densities; and

using said second recorded light intensity levels in said another scanner of said first type for generating said another tonal response curve corresponding to said another scanner.

10. The method of claim 1 wherein said method is repeated throughout a lifecycle of a device in which said tonal response curve is used to automatically calibrate said tonal response curve.

11. A method for generating a tonal response curve for use with a device having a light source directing light at a target and having an image sensor for receiving light reflected from said target, comprising:

(a) directing light from said light source to a calibration target having a single uniform neutral tone;

(b) measuring with said image sensor an amount of incident light reflected from said calibration target to obtain a simulated optical density value associated with said calibration target and said amount of incident light;

(c) changing said amount of said incident light;

(d) repeating acts (b) and (c) until a predetermined number of simulated optical density values are accumulated; and

(e) generating said tonal response curve for said image sensor by matching each of said simulated optical density values with one of a plurality of reference optical densities.

12. The method of claim 11 wherein said uniform neutral tone of said calibration target is any tone adhering to the equations luminance L*>TL and chrominance a*& b*<Tab as defined in CIELAB color space, where TL and Tab are predetermined thresholds.

13. The method of claim 11 wherein said changing said amount of said incident light is performed by changing a light intensity of said light directed from said light source.

14. The method of claim 11 wherein said device is a multifunction machine.

15. The method of claim 11 , further comprising scanning with said scanner a plurality of reference targets to generate said plurality of reference optical densities.

16. The method of claim 15 , further comprising storing in a memory first light intensity levels associated with said simulated optical density values and second light intensity levels associated with said plurality of reference optical densities.

17. The method of claim 16 , further comprising recalibrating said tonal response curve throughout a lifecycle of said device in which said tonal response curve is used based on said first light intensity levels and said second light intensity levels stored in said memory.

18. The method of claim 11 wherein said device is one of a plurality of devices of a first type, and further comprising:

recording first light intensity levels used by said device in generating said simulated optical density values; and

using said first light intensity levels in another device of said first type for generating another tonal response curve corresponding to said another device.

19. The method of claim 18 , further comprising:

recording second light intensity levels used by said device in generating said plurality of reference optical densities; and

using said second recorded light intensity levels in said another device of said first type for generating said another tonal response curve corresponding to said another device.

20. The method of claim 11 wherein said method is repeated throughout a lifecycle of said device to automatically calibrate said tonal response curve.

Assignments (8)