Pictorial digital image processing incorporating image and output device modifications

• US 20010009590A1
• Filed: 01/29/2001
• Published: 07/26/2001
• Est. Priority Date: 03/24/1997
• Status: Active Grant

• Current Assignee: RPX Corporation
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Holm, Jack M.
• Granted Patent: US 6,563,945 B2
• Time in Patent Office: Days
• US Class Current: 382/162
• CPC Class Codes: H04N 1/4072 dependent on the contents of the original
• CPC Class Codes: H04N 1/6027 Correction or control of colour gradation or colour contrast H04N1/6058 takes precedence
• CPC Class Codes: H04N 1/603 controlled by characteristics of the picture signal generator or the picture reproducer
• CPC Class Codes: H04N 1/6088 by viewing conditions, i.e. conditions at picture output
• CPC Class Codes: H04N 23/88 for colour balance, e.g. white-balance circuits or colour temperature control
• CPC Class Codes: H04N 9/64 Circuits for processing colour signals H04N9/77 takes precedence; camera processing pipelines for processing colour signals H04N23/84
• CPC Class Codes: H04N 9/69 for modifying the colour signals by gamma correction controlling camera response for colour signals H04N23/83

Abstract

Image-dependent tone and color reproduction processing of digital images is accomplished by creating a spatially blurred and sub-sampled version of the original image, and applying knowledge of the capture device physical characteristics to obtain statistics related to the scene or original captured. The statistics are used for image-dependent linearization of the captured image data based on an OECF model, and in conjunction with information about the output medium, to calculate image-specific preferred tone reproduction curves based on a preferred reproduction model. These curves may be applied to the red, green, and blue channels of RGB-type images to produce preferred tone and color reproduction, or to the luminance channel of luminance-chrominance type images to produce preferred tone reproduction. Alternately, the linearized image data may be reproduced directly. Also, if the original is assumed to already possess preferred reproduction, the preferred reproduction model may be used to undo the preferred reproduction on the original. The image data can then be processed for reproduction on output media with different density ranges and color gamuts. All the processing described can be accomplished automatically, but the access to accurate scene information afforded by the image-dependent linearization, and to the perceptually intuitive parameters controlling the calculation of the preferred reproduction curves, also allows for simple, intuitive manual adjustment.

Claims

1. A method of pictorial digital image processing comprising the steps of:

providing an original image;

gathering preliminary information;

constructing one or more of an image-dependent flare model, an image-dependent non-linearity model, an image-dependent preferred reproduction model, and an output-dependent preferred reproduction model in accordance with the preliminary information; and

processing the original image in accordance with the preliminary information and the one or more of an image-dependent flare model, an image-dependent non-linearity model, an image-dependent preferred reproduction model, and an output-dependent preferred reproduction model to produce a processed image from the original image.

2. A method of pictorial digital image processing comprising the steps of:

providing an original image;

constructing a scaled image based on the original image;

deriving image statistics from the scaled image; and

processing the original image in accordance with the image statistics derived from the scaled image.

3. The method of

claim 2

wherein the step of processing the original image comprises using the image statistics to determine image-dependent linearization information and applying the linearization information to one of the original image and the scaled image.

4. The method of

claim 2

wherein the step of processing the original image comprises determining image-dependent reproduction characteristics from the image statistics and applying the reproduction characteristics to one of the original image and the scaled image.

5. The method of

claim 2

wherein the step of constructing a scaled image comprises spatially blurring the original image to produce a blurred image and sub-sampling the blurred image.

6. A method of pictorial digital image processing comprising the steps of:

determining scene luminance statistics of an original image;

determining output media density ranges of output media to be used for viewing a processed image;

determining image- and output-dependent preferred reproduction curves based on the scene luminance statistics and the output media density ranges; and

applying the reproduction curves to the original image to produce a processed image.

7. The method of

claim 6

wherein the step of determining the preferred reproduction curves comprises constructing a reproduction model based on the image and output dependent reproduction curves.

8. The method of

claim 6

wherein the step of determining the preferred reproduction curves comprises taking into account conditions under which the processed image will be viewed.

9. The method of

claim 6

wherein the step of determining the output density range comprises assuming it to be an output density range of a standard output device.

10. A method of pictorial digital image processing wherein images are processed in an RGB color space to produce preferred tone and color reproduction characteristics in a processed image, the method comprising the steps of:

determining whether original image data is in the RGB color space, which RGB color space includes a plurality of channels;

transforming the original image data into the RGB color space if the original image data is not already in the RGB color space;

determining a tone reproduction transformation using a preferred reproduction model;

and

applying the tone reproduction transformation to each of the RGB channels to produce the preferred tone reproduction characteristics, as well as the associated color reproduction characteristics, in a processed image.

11. The method of

claim 10

wherein the step of determining a tone reproduction transformation comprises determining a relationship between a luminance channel of the original image data and a luminance channel of the processed image data.

12. A method of pictorial digital image processing wherein image data relating to an original reproduction on a first output medium are processed for a desired reproduction on a second output medium, the method comprising the steps of:

specifying a nature of the original reproduction on the first output medium;

obtaining image data related to the original reproduction on the first output medium, either data used to produce the original reproduction or data obtained by capturing the original reproduction;

transforming the image data related to the original reproduction to a color space appropriate for applying a preferred reproduction model, if necessary; and

processing data for the desired reproduction on the second output medium based on the preferred reproduction model.

13. The method of

claim 12

wherein the first and second output media are the same, but the original and desired reproduction are different.

14. The method of

claim 12

wherein the first and second output media are different, but the original and desired reproduction are the same.

15. The method of

claim 12

wherein the first and second output media and the original and desired reproduction are different.

16. A method of pictorial digital image processing comprising the steps of:

providing an original image;

constructing a preferred reproduction model;

processing the original image in accordance with the preferred reproduction model to produce a processed image; and

allowing adjustment of the processed image by providing for adjustment of a parameter of the preferred reproduction model.

17. The method of

claim 16

wherein the parameter for which adjustment is provided is one or more of:

a channel multiplier;

a scale factor used to create a scaled image;

a model value resulting from an estimate of a scene key made by the preferred reproduction model;

a model value resulting from an estimate made by the preferred reproduction model of a relation between a scene luminance range and an output density range;

a scene Zone 1 output density;

a scene Zone 5 output density; and

a scene Zone 9 output density.