Image processing method and apparatus

• US 6,445,831 B1
• Filed: 02/10/1999
• Issued: 09/03/2002
• Est. Priority Date: 02/10/1998
• Status: Expired due to Term

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Photo Film Co Limited (Fujifilm Holdings Corporation)
• Inventors: Arai, Hisao
• Primary Examiner(s): LEE, TOMMY D
• Application Number:
  US09/244,950
• Time in Patent Office: 1,301 Days
• Field of Search: 382/263, 382/264, 382/266, 382/275, 382/254, 382/260, 382/262, 382/308, 358/447, 358/448, 358/463
• US Class Current: 382/254
• CPC Class Codes: G06T 5/75 Unsharp masking
• CPC Class Codes: H04N 1/409 Edge or detail enhancement; Noise or error suppression

Abstract

Graininess suppression image processing is carried out on an original image signal, and a graininess suppression processing image signal is obtained from the graininess suppression image processing. Also, sharpness enhancement image processing is carried out on the original image signal, and a sharpness enhancement processing image signal is obtained from the sharpness enhancement image processing. Processing for obtaining a processed image signal is carried out in accordance with the graininess suppression processing image signal and the sharpness enhancement processing image signal. The processed image signal is obtained with operation processing carried out on image signal components of the graininess suppression processing image signal and the sharpness enhancement processing image signal, which image signal components represent corresponding pixels in two images represented by the graininess suppression processing image signal and the sharpness enhancement processing image signal.

Claims

1. An image processing method, wherein predetermined processing is carried out on an original image signal, which is made up of a series of image signal components defining values of pixels constituting an original image, and a processed image signal is thereby obtained, the method comprising the steps of:

i) carrying out graininess suppression image processing on the original image signal, a graininess suppression processing image signal being obtained from said graininess suppression image processing,

ii) carrying out sharpness enhancement image processing on the original image signal, a sharpness enhancement processing image signal, a sharpness enhancement processing image signal being obtained from said sharpness enhancement image processing, and

iii) carrying out processing for obtaining the processed image signal in accordance with said graininess suppression processing image signal and said sharpness enhancement processing image signal, the processed image signal being obtained with operation processing carried out on image signal components of said graininess suppression processing image signal and said sharpness enhancement processing image signal, which image signal components represent corresponding pixels in two images represented by said graininess suppression processing image signal and said sharpness enhancement processing image signal,

wherein a calculation is made to find a difference between image signal components of said graininess suppression processing image signal and the original image signal, which image signal components represent corresponding pixels in two images represented by said graininess suppression processing image signal and the original image signal,

the calculated difference and a predetermined threshold value are compared with each other,

with respect to pixels, which have been found, as a result of said comparison, to be associated with the difference smaller than said predetermined threshold value, the processed image signal is obtained with said operation processing, and

with respect to pixels, which have been found, as a result of said comparison, to be associated with the difference larger than said predetermined threshold value, the original image signal, and enhancement processing signal, which is obtained by carrying out enhancement processing on the original image signal, or said sharpness enhancement processing image signal is taken as the processed image signal.

2. A method as defined in claim 1 wherein said predetermined threshold value takes a value falling within the range of 1% to 20% of the number of gradation levels of the original image signal.

3. A method as defined in claim 1 wherein said operation processing is operation processing defined with the formula:

4. A method as defined in claim 1 wherein said operation processing is operation processing defined with the formula:

5. A method as defined in claim 1 wherein said sharpness enhancement image processing is processing comprising the steps of:

a) separating the original image signal into low frequency components, middle frequency components, and high frequency components,

b) carrying out enhancement and suppression processing such that said high frequency components may be enhanced and said middle frequency components may be suppressed, and

c) combining said high frequency components and said middle frequency components, which have been obtained from said enhancement and suppression processing, and said low frequency components with one another, said sharpness enhancement processing image signal being thereby obtained, and

said graininess suppression image processing is smoothing processing in accordance with a morphology operation.

6. A method as defined in claim 5 wherein said smoothing processing in accordance with said morphology operation is processing comprising the steps of:

a) carrying out opening processing in accordance with a morphology operation on the original image signal, an opening processing image signal being obtained from said opening processing,

b) carrying out closing processing in accordance with the morphology operation on the original image signal, a closing processing image signal being obtained from said closing processing, and

c) carrying out operation processing in accordance with said opening processing image signal and said closing processing image signal, said operation processing being carried out on image signal components of said opening processing image signal and said closing processing image signal, which image signal components represent corresponding pixels in two images represented by said opening processing image signal and said closing processing image signal, said operation processing being defined with the formula;

$\begin{array}{cc}\mathrm{fout}=\{\begin{array}{cc}\mathrm{fopn}& \left(\mathrm{if}<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{fcls}=\mathrm{fin}\right)\\ \mathrm{fcls}& \left(\mathrm{if}<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{fopn}=\mathrm{fin}\right)\\ \mathrm{w1}·<br><br>\mathrm{fopn}+\mathrm{w2}·<br><br>\mathrm{fcls}& \left(\mathrm{else}\right)\end{array}& \left(3\right)\end{array}$

 

wherein w1 and w2 represent weight factors, w1+w2=1 (0<

w1<

1, 0<

w2<

1), fin represents the original image signal, fout represents the graininess suppression processing image signal, fopn represents the opening processing image signal, and fcls represents the closing processing image signal.

7. A method as defined in claim 6 wherein each of said weight factors w1 and w2 takes a value of 0.5.

8. A method as defined in claim 5 wherein said smoothing processing in accordance with said morphology operation is processing comprising the steps of:

a) carrying out opening processing in accordance with a morphology operation on the original image signal, an opening processing image signal being obtained from said opening processing,

b) carrying out closing processing in accordance with the morphology operation on the original image signal, a closing processing image signal being obtained from said closing processing, and

c) carrying out operation processing in accordance with said opening processing image signal and said closing processing image signal, said operation processing being carried out on image signal components of said opening processing image signal and said closing processing image signal, which image signal components represent corresponding pixels in two images represented by said opening processing image signal and said closing processing image signal, said operation processing being defined with the formula;

9. An image processing apparatus, wherein predetermined processing is carried out on an original image signal, which is made up of a series of image signal components defining values of pixels constituting an original image, and a processed image signal is thereby obtained, the apparatus comprising:

i) a graininess suppression processing means for carrying out graininess suppression image processing on the original image signal, a graininess suppression processing image signal being obtained from said graininess suppression image processing,

ii) a sharpness enhancement processing means for carrying out sharpness enhancement image processing on the original image signal, a sharpness enhancement processing image signal being obtained from said sharpness enhancement image processing, and

iii) a signal processing means for carrying out processing for obtaining the processed image signal in accordance with said graininess suppression processing image signal, which has been obtained from said graininess suppression processing means, and said sharpness enhancement processing image signal, which has been obtained from said sharpness enhancement processing means, the processed image signal being obtained with operation processing carried out on image signal components of said graininess suppression processing image signal and said sharpness enhancement processing image signal, which image signal components represent corresponding pixels in two images represented by said graininess suppression processing image signal and said sharpness enhancement processing image signal,

wherein the apparatus further comprises a comparison means for calculating a difference between image signal components of said graininess suppression processing image signal, which has been obtained from said graininess suppression processing means, and the original image signal, which image signal components represent corresponding pixels in two images represented by said graininess suppression processing image signal and the original image fin, and comparing the calculated difference and a predetermined threshold value with each other, and

said signal processing means carries out processing, which comprises the steps of;

a) with respect to pixels, which have been found, as a result of said comparison made by said comparison means, to be associated with the difference smaller than said predetermined threshold value, obtaining the processed image signal by carrying out said operation processing on the image signal components of said graininess suppression processing image signal and said sharpness enhancement processing image signal having been obtained from said sharpness enhancement processing means, which image signal components represent corresponding pixels in two images represented by said graininess suppression processing image signal and said sharpness enhancement processing image signal, and

b) with respect to pixels, which have been found, as a result of said comparison, to be associated with the difference larger than said predetermined threshold value, taking the original image signal, an enhancement processing signal, which is obtained by carrying out enhancement processing on the original image signal, or said sharpness enhancement processing image signal as the processed image signal.

10. An apparatus as defined in claim 9 wherein said predetermined threshold value takes a value falling within the range of 1% to 20% of the number of gradation levels of the original image signal.

11. An apparatus as defined in claim 9 wherein said operation processing, which is carried out by said signal processing means, is operation processing defined with the formula:

12. An apparatus as defined in claim 9 wherein said operation processing, which is carried out by said signal processing means, is operation processing defined with the formula:

13. An apparatus as defined in claim 9 wherein said sharpness enhancement image processing, which is carried out by said sharpness enhancement processing means, is processing comprising the steps of:

a) separating the original image signal into low frequency components, middle frequency components, and high frequency components,

b) carrying out enhancement and suppression processing such that said high frequency components may be enhanced and said middle frequency components may be suppressed, and

c) combining said high frequency components and said middle frequency components, which have been obtained from said enhancement and suppression processing, and said low frequency components with one another, said sharpness enhancement processing image signal being thereby obtained, and

said graininess suppression image processing, which is carried out by said graininess suppression processing means, is smoothing processing in accordance with a morphology operation.

14. An image processing apparatus, wherein predetermined processing is carried out on an original image signal, which is made up of a series of image signal components defining values of pixels constituting an original image, and a processed image signal is thereby obtained, the apparatus comprising:

i) a graininess suppression processing means for carrying out graininess suppression image processing on the original image signal, a graininess suppression processing image signal being obtained from said graininess suppression image processing,

ii) a sharpness enhancement processing means for carrying out sharpness enhancement image processing on the original image signal, a sharpness enhancement processing image signal being obtained from said sharpness enhancement image processing, and

iii) a signal processing means for carrying out processing for obtaining the processed image signal in accordance with said graininess suppression processing image signal, which has been obtained from said graininess suppression processing means, and said sharpness enhancement processing image signal, which has been obtained from said sharpness enhancement processing means, the processed image signal being obtained with operation processing carried out on image signal components of said graininess suppression processing image signal and said sharpness enhancement processing image signal, which image signal components represent corresponding pixels in two images represented by said graininess suppression processing image signal and said sharpness enhancement processing image signal,

wherein said graininess suppression processing means comprises;

a) a morphology operation processing means for carrying out opening processing and closing processing in accordance with a morphology operation, respectively, on the original image signal, an opening processing image signal being obtained from said opening processing, a closing processing image signal being obtained from said closing processing, and

b) a signal processing means for carrying out processing for obtaining said graininess suppression processing image signal in accordance with said opening processing image signal and said closing processing image signal, which have been obtained from said morphology operation processing means, said graininess suppression processing image signal being obtained with operation processing carried out on image signal components of said opening processing image signal and said closing processing image signal, which image signal components represent corresponding pixels in two images represented by said opening processing image signal and said closing processing image signal, said operation processing being defined with the formula;

$\begin{array}{cc}\mathrm{fout}=\{\begin{array}{cc}\mathrm{fopn}& \left(\mathrm{if}<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{fcls}=\mathrm{fin}\right)\\ \mathrm{fcls}& \left(\mathrm{if}<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{fopn}=\mathrm{fin}\right)\\ \mathrm{w1}·<br><br>\mathrm{fopn}+\mathrm{w2}·<br><br>\mathrm{fcls}& \left(\mathrm{else}\right)\end{array}& \left(3\right)\end{array}$

 

wherein w1 and w2 represent weight factors, w1+w2=1 (0<

w1<

1, 0<

w2<

1), fin represents the original image signal, fout represents the graininess suppression processing image signal, fopn represents the opening processing image signal, and fcls represents the closing processing image signal.

15. An apparatus as defined in claim 14 wherein each of said weight factors w1 and w2 takes a value of 0.5.

16. An image processing apparatus, wherein predetermined processing is carried out on an original image signal, which is made up of a series of image signal components defining values of pixels constituting an original image, and a processed image signal is thereby obtained, the apparatus comprising:

i) a graininess suppression processing means for carrying out graininess suppression image processing on the original image signal, a graininess suppression processing image signal being obtained from said graininess suppression image processing,

ii) a sharpness enhancement processing means for carrying out sharpness enhancement image processing on the original image signal, a sharpness enhancement processing image signal being obtained from said sharpness enhancement image processing, and

iii) a signal processing means for carrying out processing for obtaining the processed image signal in accordance with said graininess suppression processing image signal, which has been obtained from said graininess suppression processing means, and said sharpness enhancement processing image signal, which has been obtained from said sharpness enhancement processing means, the processed image signal being obtained with operation processing carried out on image signal components of said graininess suppression processing image signal and said sharpness enhancement processing image signal, which image signal components represent corresponding pixels in two images represented by said graininess suppression processing image signal and said sharpness enhancement processing image signal,

wherein said graininess suppression processing means comprises;

a) a morphology operation processing means for carrying out opening processing and closing processing in accordance with a morphology operation, respectively, on the original image signal, an opening processing image signal being obtained from said opening processing, a closing processing image signal being obtained from said closing processing, and

b) a signal processing means for carrying out processing for obtaining said graininess suppression processing image signal in accordance with said opening processing image signal and said closing processing image signal, which have been obtained from said morphology operation processing means, said graininess suppression processing image signal being obtained with operation processing carried out on image signal components of said opening processing image signal and said closing processing image signal, which image signal components represent corresponding pixels in two images represented by said opening processing image signal and said closing processing image signal, said operation processing being defined with the formula;

17. An image processing method, wherein predetermined processing is carried out on an original image signal, which is made up of a series of image signal components defining values of pixels constituting an original image, and a graininess suppression processing image signal is thereby obtained, the method comprising the steps of:

i) carrying out opening processing in accordance with a morphology operation on the original image signal, an opening processing image signal being obtained from said opening processing,

ii) carrying out closing processing in accordance with the morphology operation on the original image signal, a closing processing image signal being obtained from said closing processing, and

iii) carrying out processing for obtaining the graininess suppression processing image signal in accordance with said opening processing image signal and said closing processing image signal, the graininess suppression processing image signal being obtained with operation processing carried out on image signal components of said opening processing image signal and said closing processing image signal, which image signal components represent corresponding pixels in two images represented by said opening processing image signal and said closing processing image signal, said operation processing being defined with the formula;

$\begin{array}{cc}\mathrm{fout}=\{\begin{array}{cc}\mathrm{fopn}& \left(\mathrm{if}<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{fcls}=\mathrm{fin}\right)\\ \mathrm{fcls}& \left(\mathrm{if}<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{fopn}=\mathrm{fin}\right)\\ \mathrm{w1}·<br><br>\mathrm{fopn}+\mathrm{w2}·<br><br>\mathrm{fcls}& \left(\mathrm{else}\right)\end{array}& \left(3\right)\end{array}$

 

wherein w1 and w2 represent weight factors, w1+w2=1 (0<

w1<

1, 0<

w2<

1), fin represents the original image signal, fout represents the graininess suppression processing image signal, fopn represents the opening processing image signal, and fcls represents the closing processing image signal.

18. A method as defined in claim 17 wherein each of said weight factors w1 and w2 takes a value of 0.5.

19. An image processing method, wherein predetermined processing is carried out on an original image signal, which is made up of a series of image signal components defining values of pixels constituting an original image, and a graininess suppression processing image signal is thereby obtained, the method comprising the steps of:

i) carrying out opening processing in accordance with a morphology operation on the original image signal, an opening processing image signal being obtained from said opening processing,

ii) carrying out closing processing in accordance with the morphology operation on the original image signal, a closing processing image signal being obtained from said closing processing, and

iii) carrying out processing for obtaining the graininess suppression processing image signal in accordance with said opening processing image signal and said closing processing image signal, the graininess suppression processing image signal being obtained with operation processing carried out on image signal components of said opening processing image signal and said closing processing image signal, which image signal components represent corresponding pixels in two images represented by said opening processing image signal and said closing processing image signal, said operation processing being defined with the formula;

20. An image processing apparatus, wherein predetermined processing is carried out on an original image signal, which is made up of a series of image signal components defining values of pixels constituting an original image, and a graininess suppression processing image signal is thereby obtained, the apparatus comprising:

i) a morphology operation processing means for carrying out opening processing and closing processing in accordance with a morphology operation, respectively, on the original image signal, an opening processing image signal being obtained from said opening processing, a closing processing image signal being obtained from said closing processing, and

ii) a signal processing means for carrying out processing for obtaining the graininess suppression processing image signal in accordance with said opening processing image signal and said closing processing image signal, which have been obtained from said morphology operation processing means, the graininess suppression processing image signal being obtained with operation processing carried out on image signal components of said opening processing image signal and said closing processing image signal, which image signal components represent corresponding pixels in two images represented by said opening processing image signal and said closing processing image signal, said operation processing being defined with the formula;

$\begin{array}{cc}\mathrm{fout}=\{\begin{array}{cc}\mathrm{fopn}& \left(\mathrm{if}<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{fcls}=\mathrm{fin}\right)\\ \mathrm{fcls}& \left(\mathrm{if}<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{fopn}=\mathrm{fin}\right)\\ \mathrm{w1}·<br><br>\mathrm{fopn}+\mathrm{w2}·<br><br>\mathrm{fcls}& \left(\mathrm{else}\right)\end{array}& \left(3\right)\end{array}$

 

wherein w1 and w2 represent weight factors, w1+w2=1 (0<

w1<

1, 0<

w2<

1), fin represents the original image signal, fout represents the graininess suppression processing image signal, fopn represents the opening processing image signal, and fcls represents the closing processing image signal.

21. An apparatus as defined in claim 20 wherein each of said weight factors w1 and w2 takes a value of 0.5.

22. An image processing apparatus, wherein predetermined processing is carried out on an original image signal, which is made up of a series of image signal components defining values of pixels constituting an original image, and a graininess suppression processing image signal is thereby obtained, the apparatus comprising:

i) a morphology operation processing means for carrying out opening processing and closing processing in accordance with a morphology operation, respectively, on the original image signal, an opening processing image signal being obtained from said opening processing, a closing processing image signal being obtained from said closing processing, and

ii) a signal processing means for carrying out processing for obtaining the graininess suppression processing image signal in accordance with said opening processing image signal and said closing processing image signal, which have been obtained from said morphology operation processing means, the graininess suppression processing image signal being obtained with operation processing carried out on image signal components of said opening processing image signal and said closing processing image signal, which image signal components represent corresponding pixels in two images represented by said opening processing image signal and said closing processing image signal, said operation processing being defined with the formula;