Method and system for matching marking device outputs

1. A method of substantially matching a first output produced by a first marking device with a second output produced by a second marking device, the method comprising the steps of:

producing a first set of one or more sample tone levels using the first marking device;

producing a second set of one or more sample tone levels using the second marking device;

comparing the first set of sample tone levels with the second set of sample tone levels;

determining one or more calibration set points;

generating a custom tone transfer function associated with the first marking device in accordance with the calibration set points;

using the custom tone transfer function to produce the first output from the first marking device

wherein:

the step of using the custom tone transfer function to produce the first output from the first printer further comprises the steps of:

reverse halftoning a raster image to divide the raster image into halftone cells; and

using the custom tone transfer function to adjust one or more halftone levels associated with the halftone cells.

2. A method of substantially matching a first output produced by a first marking device with a second output produced by a second marking device, the method comprising the steps of:

producing a first set of one or more sample tone levels using the first marking device;

producing a second set of one or more sample tone levels using the second marking device;

comparing the first set of sample tone levels with the second set of sample tone levels;

determining one or more calibration set points;

generating a custom tone transfer function associated with the first marking device in accordance with the calibration set points;

using the custom tone transfer function to produce the first output from the first marking device; and,

overriding an embedded tone transfer function associated with a PDL-encoded image to be produced on the first marking device.

3. A marking system capable of substantially matching a first output produced by a first marking device with a second output produced by a second marking device, the system comprising:

an optical sensor;

an image processing subsystem; and

a marking engine associated with the first marking device;

wherein the optical sensor is configured to determine one or more calibration set points by comparing a first set of one or more sample tone levels produced by the first marking device with a second set of one or more sample tone levels produced by the second marking device;

wherein the image processing subsystem is configured to:

receive an image from a client application;

generate a custom tone transfer function in accordance with the calibration set points; and

process the image using the custom tone transfer function to create a rasterized pixel stream; and

wherein the marking engine is configured to receive the rasterized pixel stream and to produce the first output.

4. A marking system as in claim 3 , wherein:

the image processing subsystem includes a client marking device driver; and

the custom tone transfer function is generated by the client marking device driver.

5. A marking system as in claim 3 , wherein:

the image processing subsystem includes a raster image processor;

the custom tone transfer function is generated by the raster image processor.

6. A first marking device capable of producing a first output that is substantially matched to a second output produced by a second marking device, the first marking device comprising:

a marking engine;

a raster image processor including a tone transfer function; and

a calibration interface;

wherein the calibration interface is configured to receive one or more calibration set points determined by comparing a first sample output produced by the first marking device with a second sample output produced by the second marking device, and to communicate the set points to the raster image processor;

wherein the raster image processor is configured to receive an input image from a client, to generate a custom tone transfer function in accordance with the calibration set points, and to process the image using the modified tone transfer function to create a matched rasterized pixel stream; and

the marking engine is configured to receive the matched rasterized pixel stream and to produce the first substantially matched output.

7. A first marking device as in claim 6 , wherein:

the tone transfer curve is implemented via a lookup table.

8. A raster image processor comprising:

a page description language interpreter,

a raster memory device; and

a microprocessor in communication with the page description language interpreter and the raster memory device; and

wherein the page description language interpreter is configured to receive a page description language image and to convert the page description language image to an intermediate image;

wherein the microprocessor is programmed to receive one or more calibration set points determined by comparing a first set of one or more sample tone levels produced by a first marking device with a second set of sample tone levels produced by a second marking device, to generate a custom tone transfer function using the calibration set points; and to apply the tone transfer function to the intermediate image to create a rasterized pixel stream;

and wherein the raster memory device is configured to receive the rasterized pixel stream and to provide the rasterized pixel stream to a first marking device such that the first marking device produces a first output that is substantially matched with a second output produced by a second marking device.

9. A system for matching a first output from a first printer with a second output from a second printer comprising:

means for comparing a first set of one or more sample tone levels produced by the first marking device with a second set of one or more sample tone levels produced by the second marking device to determine one or more calibration set points;

means for generating a custom tone transfer function in accordance with the calibration set points to generate a modified tone transfer function;

an image processing subsystem configured to receive an image from a client application and to process the image using the modified tone transfer function to create a rasterized pixel stream;

a marking engine associated with the first marking device, wherein the marking engine is configured to receive the rasterized pixel stream and to produce the first output.