Facsimile and static presentation processing – Static presentation processing – Attribute control
Reexamination Certificate
1998-04-09
2001-05-08
Coles, Edward L. (Department: 2722)
Facsimile and static presentation processing
Static presentation processing
Attribute control
C358S518000, C358S519000, C358S521000, C345S156000, C345S156000
Reexamination Certificate
active
06229624
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a method of constructing a transform for improving the display or making prints from digital images.
BACKGROUND OF THE INVENTION
It is important in producing displays or prints from digital images to fit the dynamic range of the originally captured scene to the dynamic range of the materials available for displaying or printing using the best possible transform. A limiting factor is the dynamic range of the materials available for displaying or printing. By selectively choosing the proper transform for displaying or printing, it is possible to display or print esthetically pleasing images on materials that have less dynamic range than the original scene.
As new materials such as thermal print media and receivers and ink jet technologies have become available for displaying or printing, they have introduced wider dynamic ranges than available with previous technologies. It is well known how to display or print digital images on these types of media. However, it is difficult to design different transforms that best take advantage of these new media. A key element in any new transform is to be able to utilize the full dynamic range of the media for displaying or printing the digital images.
There have been a number of techniques for improving the tone reproduction of digital images, see for example, U.S. Pat. No. 4,792,518 and U.S. Pat. No. 5,300,381. For a discussion of tone reproduction and the effect of flare on print quality, see “The Tone Reproduction of Colour Photographic Materials,” R. W. G. Hunt, I. T. Pitt, and P. C. Ward, J. Photog. Sci., 17:198(1969). Flare light is generally ambient light which degrades the viewed image on the print.
As set forth in the above disclosures, a number of techniques are disclosed which require that the media be silver halide photographic media and the techniques for making the images are very complex. The publication by Hunt et al describes the “ideal system” for printing photographic images to correct for camera flare, printer flare, and viewing flare but offered no practical way to implement this theoretical tone reproduction curve because of the lack of digital imaging tools and the limitations of the materials available in 1969.
U.S. Pat. No. 5,528,339 discloses techniques for improving the tone reproduction of digital images on other media such as thermal, ink jet and electrophotographic. However, the presently available media for the printing of the digital images far exceeds the dynamic range previously described by having lower minimum densities and considerably higher maximum densities.
SUMMARY OF THE INVENTION
It is an object of the present invention to facilitate the printing of digital images with improved tone reproduction and ensuring that such images provide esthetically pleasing results and which minimizes the effects of flare and permits a better fit of the dynamic range of the original scene to the dynamic range of the print media. In the process of capturing digital images and making prints from such digital images, flare is introduced in two ways. The first is by ambient light at the time of capture, and the second is by ambient light at the time of viewing of the print or display. In a typical silver halide photographic process, flare takes place in three ways. The first is at the time of exposure. The second is when the optical print is made. The third is when the optical print is viewed.
It is another object of the present invention to provide new techniques for improving the image quality of digital images on displays with a wider dynamic range than previously available.
These objects are achieved by in a method for selecting an aim curve for a desired medium having a predetermined maximum density, comprising the steps of:
a) selecting an aim curve from a family of aim curves for a different medium having a lower predetermined maximum density than that of the desired medium, the aim curve having shadow, midtone, and highlight regions;
b) varying the shadow contrast in the shadow region of the selected aim curve to produce a different aim curve; and
c) determining the different aim curve with the desired medium that has an improved shadow contrast that will produce prints with reduced flare and permits a better fit of the dynamic range of the original scene to the dynamic range of the medium.
The present invention recognizes that unlike the typical silver halide photographic process when prints are made from digital images, flare, is also a function only of ambient light which takes place at the time of camera exposure and as well as ambient light when viewing the print or display. It is therefore an advantage of the present invention to produce a transform which can be used either in soft displays for displaying images or for use in printing black and white or colored images and which minimizes the effects of flare and permits a better fit of the dynamic range of the original scene to the dynamic range of the print media. This technique can be readily implemented in a computing system. Such a computing system can include a microprocessor which can produce continuous tone prints which are esthetically pleasing.
In accordance with the present invention, the original scene image is not duplicated, but the tone reproduction of it's corresponding digital image is shaped so as to produce an esthetically pleasing display or print which minimizes flare effects and permits a better fit of the dynamic range of the original scene to the dynamic range of the print media.
It is a feature of the present invention that it optimizes tone reproduction in the Dmin (minimum image reflection density) and Dmax (maximum image reflection density) regions of display or print material.
REFERENCES:
patent: 4792518 (1988-12-01), Kuwashima et al.
patent: 5300381 (1994-04-01), Buhr et al.
patent: 5528339 (1996-06-01), Buhr et al.
patent: 5913014 (1999-06-01), Gilman, Jr. et al.
“The Tone Reproduction of Colour Photographic Material,” R.W.G. Hunt, I.T. Pitt, and P.C. Ward, J. Photog. Sci., 17:198(1969).
W.H. Carnahan inPhotographic Engineering, 6, 237 (1955).
Adobe Photoshop Software Program 3.0 or 4.01 manufactured by Adobe, San Jose, CA.
Gilman Paul B.
Hamilton, Jr. John F.
Vogel Richard M.
Coles Edward L.
Eastman Kodak Company
Lamb Twyler
Owens Raymond L.
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