Image analysis – Image enhancement or restoration – Artifact removal or suppression
Reexamination Certificate
2000-03-22
2004-08-10
Wu, Jingge (Department: 2723)
Image analysis
Image enhancement or restoration
Artifact removal or suppression
C382S167000, C250S341700
Reexamination Certificate
active
06775419
ABSTRACT:
The entire disclosure of Japanese Patent Application No. 9-198635 including specification, claims, drawings and summary is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image processing method for correcting the influences of defects such as dust, scratches, fingerprints, and the like present on a transparent original upon reading image information of the transparent original, an image processing apparatus for executing the image processing method, and a storage medium for computer-readably storing a program for correcting the influences of defects.
2. Related Background Art
An image processing apparatus for reading image information of a transparent original is normally constituted by a host computer such as a so-called personal computer, or the like, and an image reader as an input device of the host computer. The image reader comprises an illumination means for illuminating a film original as a transparent original such as a negative film, reversal film, elongated film, or the like, a moving means for moving the film original, an image reading means for reading an image on the film original by receiving light transmitted through the film original, and outputting an image signal, and an image processing means for calculating data of the image read by the image reading means. The image reader reads an image on a film original on the basis of a command from the host computer, and outputs the read image data to the host computer.
Color image reading is normally done by switching three colors, i.e., red (R), green (G), and blue (B). However, when defects such as dust, scratches, fingerprints, and the like are present on a film original, these defects appear as black points (in case of a positive film) or white points (in case of a negative film) on the read image, thus lowering the image quality.
To solve such problem, a technique for detecting defects such as dust, scratches, fingerprints, and the like using the properties of infrared light and correcting the influences of defects has been proposed (e.g., U.S. Pat. No. 5,266,805). This patent discloses the following technique. That is, when the infrared ray energy intensity detected at a given timing is larger than a predetermined threshold value, the visible ray energy intensity is increased to a level that can cancel the infrared ray energy intensity, and when the detected infrared ray energy intensity is equal to or lower than the predetermined threshold value, the visible ray energy intensity is corrected by interpolation, thereby correcting the influences of defects.
However, the above patent discloses only the concept of the technique for correcting the influences of defects using infrared rays, and does not give any clear description about how to compute the acquired data associated with defects so as to acquire correction data. Hence, the disclosure of the above patent does not enable acquisition of an image free from the influences of defects.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an image processing method that can surely acquire an image free from the influences of defects on a transparent original, an image processing apparatus for executing the image processing method, and a storage medium for computer-readably storing a program for correcting the influences of defects.
An image processing method according to the basic mode of the present invention comprises the steps of resolving the color of an image on a transmissive substrate or original to extract an infrared component (i.e., providing an infrared light component transmitted by a transparent original), detecting the level of the infrared component, detecting a defect infrared component level at a defect position on the transparent original where the infrared component level becomes lower than a first infrared level, obtaining a correction factor by calculating (first infrared component level)/(defect infrared component level) on the basis of the first infrared component level and defect infrared component level, resolving the color of the image on the transparent original to extract a visible component, detecting a visible component level of the visible component, and calculating a corrected visible component level by multiplying a defect visible component level at the defect position on the transparent original by the correction factor.
Noting that the attenuation amount of the transmissive level of the infrared component accurately represents the degree of defects, this method calculates the correction factor as the ratio between the infrared component level (first infrared component level) obtained without any defects and the defect infrared component level at the defect position, and multiplies the visible component level at that defect position by the correction factor. Therefore, since correction can be attained in correspondence with the attenuation amount, an image can be reproduced more appropriately than the conventional method.
In order to make this image processing method properly function, the visible component at the defect position must include recoverable image information. Hence, in one mode of the present invention, a threshold value as a second infrared component level is used as a reference infrared component level, and when the degree of defects is not too serious and image information can be directly recovered, the correction factor is multiplied. In this way, an image can be reproduced more appropriately.
In the image processing method according to one mode of the present invention, when the degree of defects is serious and the infrared component level is smaller than the second infrared component level component, i.e., image information cannot be directly recovered, a visible component level at the defect position is generated using visible component levels around the detected defect position. Hence, even at a position where the attenuation amount due to defects is large, an image which suffers less influences of defects can be obtained.
In the image processing method of the present invention, the first infrared component level can use a maximum value of the detected infrared component levels. In this case, even when the infrared component level varies in each detection, the influences of such variations can be reduced, thus reducing the influences of defects with high reproducibility.
In the image processing method according to one mode of the present invention, the infrared component is extracted by optically resolving the color of the image on the transparent original to extract an infrared component, the infrared component level is detected by imaging infrared light corresponding to the extracted infrared component on photoelectric conversion means by an imaging optical system, and making the photoelectric conversion means output an infrared component signal, the visible component is extracted by optically resolving the color of the image on the transparent original to extract a visible component, the visible component level is detected by imaging visible light corresponding to the extracted visible component on the photoelectric conversion means by the imaging optical system, and making the photoelectric conversion means output a visible component signal, and the method further comprises the step of performing registrational error correction for correcting a registrational error between the infrared component signal and visible component signal due to different imaging positions of the infrared light coming from the transparent original and the visible light coming from the transparent original, that are caused by characteristics of the imaging optical system. With this method, any influences of the registrational error between the focused positions of infrared light and visible light caused by the characteristics of the imaging optical system can be corrected. As a consequence, the size of the infrared component signal region corresponding to defects becomes nearly equal to that of the visible compo
Fujinawa Nobuhiro
Maeda Eisaku
Shirahata Takuya
Nikon Corporation
Wu Jingge
LandOfFree
Image processing method, image processing apparatus, and... 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, image processing apparatus, and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Image processing method, image processing apparatus, and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3303177