Image analysis – Color image processing – Color correction
Reexamination Certificate
1999-03-25
2003-08-05
Wu, Jingge (Department: 2623)
Image analysis
Color image processing
Color correction
C358S520000, C358S521000
Reexamination Certificate
active
06603878
ABSTRACT:
BACKGROUND OF INVENTION
This invention relates to an image processing method for reproducing a visible image from color negative image signals obtained by photoelectrically reading the color negative image carried on a color negative film. The invention particularly relates to an image processing method capable of processing a color negative image to have a finish like color reversal images reproduced from reversal films.
A digital color image reproducing system has been proposed and commercialized as a digital photoprinter. According to the system, the color image recorded on a negative film, a reversal film or a color print is read photoelectrically with a photoelectric transducer such as a CCD (charge coupled device) and converted to digital signals which are then stored as original image signals in an image signal storage means such as a frame memory and the image signals stored in an image data storage means are subjected to image processing to reproduce a color image on a recording material such as color paper or a display means such as a CRT (cathod-ray tube).
An advantage of the digital color image reproducing system is that even if the original color image taken under inappropriate conditions such as under- or over-exposure is recorded on a negative film, a reversal film or a color print, a color image having the desired color and gradation can be reproduced by performing image processing on the obtained original image signals. As a further advantage, the color image recorded on a negative film, a reversal film or a color print can upon request be reproduced as a color image of a different color and gradation.
Reversal prints reproduced from color reversal films are characterized by having a higher overall density and contrast than color negative prints reproduced from color negative films and being capable of rendering the sky deep blue and presenting with good graininess. These features are favored by scenes of landscape. On the other hand, color negative prints reproduced from color negative films are less favorable in the representation of landscape scenes even if they are processed to have an optimal finish.
Particularly in terms of graininess, the digital color image reproducing system produces color reversal prints of better quality than color negative prints for the following reasons. The system requires that the color image carried on a transparency such as a color negative film or a color reversal film be read photoelectrically with transmitted light by an imaging means such as a CCD so that it is converted to color image signals. Therefore, less light is transmitted through the shadow region of the transparency and only weak image signals are captured with the imaging means such as a CCD. On the other hand, more light is transmitted through the highlight region and strong image signals are captured with the imaging means. As a result, the noise of the imaging means is not likely to be superimposed on the image signals captured from the highlight region of the transparency whereas the same noise is highly prone to be superposed on the image signals captured from the shadow region.
The shadow region of a color reversal film corresponds to the shadow region of a color reversal print and is graininess inherently less visible even if noise is superposed. On the other hand, the shadow region of a color negative film becomes the highlight region of a color negative print, so any noise superposed on the captured image signals is sufficiently reproduced to deteriorate the graininess, thereby increasing the visibility of coarse texture.
To deal with these problems, it is strongly desired that the digital photoprinter, when reproducing a color print from a landscape scene on a color negative film, should generate a color image reproduction in which the original landscape scene is processed to produce a reversal-like finish, i.e., as if it were in a color reversal print reproduced from a color reversal film.
SUMMARY OF THE INVENTION
The present invention has been accomplished under these circumstances and has as an objective providing an image processing method that is applicable to the digital image processing of color negative image signals obtained by photoelectric reading of a color negative image and by which an original color negative image, if it represents a particular picture like a landscape scene, can be finished as if it were in a reversal print suitable for the reproduction of the particular picture like a landscape scene.
The stated object of the invention can be attained by an image processing method in which a color negative image is read photoelectrically and color negative image signals obtained by image reading are subjected to specified image processing, comprising the steps of:
if said color negative image is designated as representing a particular picture,
subjecting said color negative image signals to gradation hardening process in which the gradation of said designated color negative image is rendered harder; and
subjecting said color negative image signals to a hue altering process in which a particular hue in said designated color negative image is altered to a desired hue.
The image processing method may further include the step of performing sharpness enhancing process on said color negative image signals.
Preferably, said sharpness enhancing process is performed by an unsharp masking technique or a graininess suppressing sharpness technique.
In each of the cases described above, said gradation hardening process and said hue altering process are preferably performed on said color negative image signals after setup process is performed.
Said setup process is preferably auto-setup process.
In each of the cases described above, said hue altering process preferably comprises the steps of:
extracting said particular hue from RGB density signals of said color negative image signals;
converting the RGB density signals of the extracted particular hue to pseudo hue, lightness and saturation signals;
determining intensities of said hue, lightness and saturation signals;
thereafter calculating an overall intensity of said particular hue; and
adding a preset amount of correction to the calculated overall intensity to generate RGB signals in which the particular hue has been altered to the desired hue.
Said particular picture is preferably a picture of landscape.
Said particular picture is preferably designated by external input.
Preferably, the particular hue which is subjected to said hue altering process is a cyan color of a sky and said desired hue is a blue color.
When said sharpness enhancing process is performed on said color negative image signals, a particular region of said color negative image that has a particular color is lowered in sharpness.
The particular color of the particular region which is to be lowered in sharpness is preferably either the cyan color of the sky, a skin color of a human subject or both.
REFERENCES:
patent: 4833532 (1989-05-01), Abe
patent: 5060060 (1991-10-01), Uadagawa et al.
patent: 5081485 (1992-01-01), Terashita
patent: 5081692 (1992-01-01), Kwon et al.
patent: 5528339 (1996-06-01), Buhr et al.
patent: 5680230 (1997-10-01), Kaburagi et al.
patent: 5739922 (1998-04-01), Matama
patent: 6091861 (2000-07-01), Keyes et al.
patent: 63026783 (1988-02-01), None
patent: 09022460 (1997-01-01), None
patent: 09083824 (1997-03-01), None
patent: 09138470 (1997-05-01), None
patent: WO 90/07751 (1990-07-01), None
Birch & Stewart Kolasch & Birch, LLP
Fuji Photo Film Co., LTD
Wu Jingge
LandOfFree
Image processing method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Image processing method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Image processing method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3086960