Image analysis – Image enhancement or restoration
Reexamination Certificate
1999-09-30
2004-04-20
Couso, Yon J. (Department: 2625)
Image analysis
Image enhancement or restoration
C382S263000, C382S298000
Reexamination Certificate
active
06724941
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image processing method, an image processing device and a recording medium, and in particular, to an image processing method which carries out spatial frequency enhancement processing on an original image signal (image data) obtained by a digital still camera under preferred processing conditions, an image processing device to which the image processing method can be applied, and a recording medium on which a program for a computer to execute the image processing method is recorded.
2. Description of the Related Art
Conventionally, with the object of turning the image quality of an image, which is expressed by an original image signal obtained by image pick-up using a video camera or photography using a digital still camera or the like, into an image quality which is visually preferable, spatial frequency enhancement processing for enhancing the sharpness of the image expressed by the above original image signal, which is known as sharpness enhancement processing, is carried out.
In carrying out sharpness enhancement processing such as that described above, an image of an image quality that is visually more preferable can be obtained by setting processing conditions according to a combination of an input device and an output device. The input device is used in obtaining an original image signal and the output device is used in outputting the image based on the original image signal. Thus, examinations have conventionally been made of preferred processing conditions for sharpness enhancement processing in accordance with a combination of various types of input devices and output devices.
Japanese Patent Application Laid-Open (JP-A) No. 61-109550 has made an examination of processing conditions of the sharpness enhancement processing in which a digital X-ray image is inputted, and the processed image is outputted onto a CRT monitor or a X-ray film.
In this way, the optimization of the processing conditions of sharpness enhancement processing in accordance with the combination of the input device and the output device has become an essential technique in realizing a high image quality.
However, since the digital still camera is a device that has been put to practical use relatively recently and only a limited number of manufacturers deal in both devices, i.e., the digital still camera and a printer for recording an original image signal, which is obtained by photography using the digital still camera, on a recording medium, there has been a problem in that, the conditions obtained as processing conditions for sharpness enhancement processing at the time when an image is recorded on a recording medium based on an original image signal obtained by photography using a digital still camera have not been necessarily the optimum ones.
Further, some types of recent digital still cameras carry out sharpness processing within the camera. In these types of digital still cameras, an output thereof is adjusted to the sharpness that is preferable for viewing on a monitor. Moreover, the image setting, which is preferable for viewing on a monitor, differs from manufacturer to manufacturer among manufacturers of digital still cameras. As a result, there exist a variety of sharpness images, and even when an image, which is preferable for viewing on a monitor, is outputted as it is by a printer, the sharpness of the image may be insufficient.
SUMMARY OF THE INVENTION
The present invention has been attained to solve the above-described problems, and an object thereof is to provide an image processing method, an image processing device and a recording medium in which spatial frequency enhancement processing can be carried out under preferred processing conditions on original image signals obtained by a digital camera, which include an original image signal of an image on which sharpness processing is not effected by a digital still camera or an original image signal of an image on which sharpness processing has been effected by a digital still camera so as to look preferable for viewing on a monitor.
In order to achieve the above object, an image processing method relating to a first aspect of the present invention carries out spatial frequency enhancement processing on an original image signal obtained by photography using a digital still camera in such a manner that the maximum value of responses of the spatial frequency characteristics of an image signal on which the spatial frequency enhancement processing has been effected is a value in the range of 1.5 to 3.0 times the maximum value of responses of the spatial frequency characteristics of the original image signal on which the spatial frequency enhancement processing has not been effected yet.
The inventors carried out a subjective evaluation experiment that utilized an image which was the result of spatial frequency enhancement processing on an original image signal that had been obtained by photography using a plurality of existing digital still cameras.
The respective conditions of the subjective evaluation experiment were as follows:
evaluators: 8 persons;
types of digital still cameras that were used for the evaluation: five types, i.e., digital still cameras from A to E;
degree of spatial frequency enhancement processing: the maximum value of responses of the spatial frequency characteristics in the image signal on which the spatial frequency enhancement processing has been effected is 1.5 times, 2.0 times, 2.5 times, 3.0 times, 3.5 times, 4.0 times or 4.5 times the maximum value of responses of the spatial frequency characteristics in the original image signal;
number of scenes to be evaluated: 10 scenes for each type of digital camera (5 scenes each having an image mainly of a person, and 5 scenes each having an image mainly of a landscape);
evaluation method: each image was compared with the original image so as to be given one of the following 5 grades
⊚: improved considerably
∘: improved
&Dgr;: in comparison with the original image, some parts were improved but others were deteriorated, or equivalent to the original image
X: deteriorated
XX: deteriorated considerably.
In table 1, an example of evaluation results for 5 scenes each having an image mainly of a landscape is shown. In table 2, an example of evaluation results for 5 scenes each having an image mainly of a person is shown.
TABLE 1
1.5
2.0
2.5
3.0
3.5
4.0
4.5
Digital camera A
&Dgr;
∘
⊚
⊚
∘
&Dgr;
x
Digital camera B
&Dgr;
∘
⊚
∘
&Dgr;
&Dgr;
&Dgr;
Digital camera C
∘
∘
&Dgr;
&Dgr;
x
xx
xx
Digital camera D
&Dgr;
∘
⊚
∘
&Dgr;
x
xx
Digital camera E
&Dgr;
⊚
∘
∘
&Dgr;
x
x
TABLE 2
1.5
2.0
2.5
3.0
3.5
4.0
4.5
Digital camera A
&Dgr;
∘
⊚
∘
&Dgr;
x
x
Digital camera B
&Dgr;
∘
∘
∘
&Dgr;
&Dgr;
&Dgr;
Digital camera C
∘
&Dgr;
&Dgr;
x
xx
xx
xx
Digital camera D
&Dgr;
⊚
∘
&Dgr;
x
xx
xx
Digital camera E
&Dgr;
∘
⊚
&Dgr;
x
xx
xx
Table 3 shows the results of the evaluation of all the scenes to be evaluated by all the evaluators. These results have been made numerical by the expression, the number of scenes to be evaluated× the number of persons. (For example, if chosen by all the evaluators, the result is 10 scenes×5 types×8 persons=400.)
TABLE 3
1.5
2.0
2.5
3.0
3.5
4.0
4.5
⊚
10
80
105
90
20
0
0
∘
210
290
250
180
115
65
25
&Dgr;
180
30
40
105
175
200
165
x
0
0
5
25
60
75
125
xx
0
0
0
0
30
60
85
ratio of
55.0%
92.5%
88.8%
67.5%
33.8%
16.3%
6.3%
⊚ and ∘
From the results of the subjective evaluation described above, the information was obtained: when the maximum value of the spatial frequency characteristics in the image signal on which the spatial frequency enhancement processing has been effected is in the range of 1.5 to 3.0 times the maximum value of responses of the spatial frequency characteristics of the original image signal, a larger proportion of evaluators (equal to or more than 50
Birch Stewart Kolasch & Birch
Couso Yon J.
Fuji Photo Film Co. , Ltd.
LandOfFree
Image processing method, image processing device, 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 device, and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Image processing method, image processing device, and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3251534