Image analysis – Image enhancement or restoration – Image filter
Reexamination Certificate
2000-09-11
2004-10-19
Patel, Kanji (Department: 2625)
Image analysis
Image enhancement or restoration
Image filter
C358S532000, C345S604000, C348S712000
Reexamination Certificate
active
06807315
ABSTRACT:
FIELD OF INVENTION
The present invention relates to a method and apparatus for sharpening an image.
The invention has been developed primarily for a digital camera including an integral printer for providing a paper print of an image captured by the camera and will be described hereinafter with reference to that application. However, it will be appreciated that the invention is not limited to that particular field of use.
SUMMARY OF INVENTION
According to a first aspect of the invention there is provided a method for sharpening an image, the method including the steps of:
receiving a data set indicative of the image; extracting an initial luminance channel from the data set;
sharpening the initial luminance channel to form a revised luminance channel; and
incorporating the revised luminance channel into the data set.
Preferably, the extracting includes the step of deriving the initial luminance channel from the data set.
More preferably, the data set has a red plane, a green plane and a blue plane and the method includes the step of deriving the initial luminance channel from the planes.
Even more preferably, the data set includes the initial luminance channel as a separate channel and the extracting includes the step of accessing the initial luminance channel. Preferably also, the sharpening includes the further steps of:
high-pass filtering the initial luminance channel to provide a filtered luminance channel; and
forming the revised luminance channel from the sum of the initial luminance channel and a predetermined proportion of the filtered luminance channel.
In a preferred form, the high-pass filtering utilises a 3×3 convolution kernel. In alternative embodiments, however, the high-pass filtering utilises a 5×5 convolution kernel. In further alternative embodiments the high-pass filtering utilises a 7×7 convolution kernel.
According to a second aspect of the invention there is provided an apparatus for sharpening an image, the apparatus including:
input means for receiving a data set indicative of the image;
extraction means for extracting an initial luminance channel from the data set;
sharpening means for sharpening the initial luminance channel to form a revised luminance channel; and
processing means for incorporating the revised luminance channel into the data set.
Preferably, the extraction means derives the initial luminance channel from the data set. More preferably, the data set has a red plane, a green plane and a blue plane and the extraction means derives the initial luminance channel from the planes.
Preferably also, the data set includes the initial luminance channel as a separate channel and the extraction means accesses the initial luminance channel.
In a preferred form, the sharpening means:
high-pass filters the initial luminance channel to provide a filtered luminance channel; and
forms the revised luminance channel from the sum of the initial luminance channel and a predetermined proportion of the filtered luminance channel.
REFERENCES:
patent: 5119179 (1992-06-01), Hagino
patent: 5121209 (1992-06-01), Smith et al.
patent: 5363209 (1994-11-01), Eschbach et al.
patent: 5374995 (1994-12-01), Loveridge et al.
patent: 5619590 (1997-04-01), Moore, Jr.
patent: 6078307 (2000-06-01), Daly
patent: 6246827 (2001-06-01), Strolle et al.
patent: 6392699 (2002-05-01), Acharya
patent: 6574363 (2003-06-01), Classen et al.
Topfer K., Adams J.E., Keelan B.W.: “Modulation Transfer Functions and Aliasing Patterns of CFA Interpolation Algorithms”. Proceedings IS&T's PICS Conference 51st Annual Conference, p. 367-370, published Springfield, VA, USA, 1998.
Parulski K A et al: “High-Performance Digital Color Videa Camera” Journal of Electronic Imaging, SPIE + IS&T, US, vol. 1, No. 1, 1992, pp. 35-45, XP000323326.
US 5,793,885 A (Kasson James Matthews); Aug. 11, 1998; abstract; col. 1, line 10-line 20; col. 2, last paragraph—line 57; col. 6, line 1-line 28; col. 6, line 39-col. 8, line 14; col. 10, line 13-line 34; col. 10, line 43-line 65.
Jaspers E G T et al. “A generic 2D sharpness enhancement algorithm for luminance signals”; Sixth International Conference on Image Processing and its Applications (Conf. Publ. No. 443), Proceedings of 6th International Conference on Image Processing and its Applications (Conf. Publ. No. 443), Dublin, Ireland, Jul. 14-17, 1997, pp. 269-273 vol. 1, XP002239857 1997, London, UK, IEE, UK ISBN: 0-85296-692-X; abstract; p. 269, left-hand column, line.
Liu N et al: “Improved Method for Color Image Enhancement Based on Luminance and Color Contrast” Journal of Electronic Imaging, SPIE + IS&T, US, vol. 3, No. 2, Apr. 1, 1994, pp. 190-197, XP000452074; issn:1017;9909; abstract; p. 190, left-hand column, line 1-page 191, left-hand column, paragraph 1; p. 191, left-hand column, paragraph 3-paragraph 4; p. 191, left-hand column, last paragraph—right-hand column, paragraph 1; p. 191, rith-hand column, last paragraph—p. 192, left-hand column, paragraph 1; p. 192, right-hand column, last paragraph; table 1.
Lapstun Paul
Walmsley Simon Robert
Patel Kanji
Silverbrook Research Pty Ltd
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