Signal processing apparatus and signal processing method setting noise strength for stochastic resonance processing

Patent metadata

Field	Value
Publication number	US-10679329-B2
Application number	US-201715458386-A
Country	US
Kind code	B2
Filing date	Mar 14, 2017
Priority date	Mar 31, 2016
Publication date	Jun 9, 2020
Grant date	Jun 9, 2020

Abstract

The noise strength setting unit sets the noise strength based on a function of a correlation coefficient between the result of the predetermined stochastic resonance processing and the detection target data and the noise strength K.

First claim

What is claimed is:

1. A signal processing apparatus, comprising:
a processor serving as:
(i) an acquisition unit configured to acquire input data having input signals I(x) corresponding to a plurality of pixel positions x respectively, and detection target data having detection target signals t(x) corresponding to the plurality of pixel positions x as a target to be detected respectively, the input data being acquired by reading an image printed by a printing apparatus and the detection target data being image data indicating a singular portion that appears and is caused by an error of the printing apparatus;
(ii) a noise strength setting unit configured to set, based on the input data and the detection target data, a noise strength K that is used to be added to the input signals I(x) to subject the input signals I(x) to a predetermined stochastic resonance processing; and
(iii) a stochastic resonance processing unit configured to use the noise strength K set by the noise strength setting unit and a threshold value T to quantize the input signals I(x) to subject the input signals I(x) to the predetermined stochastic resonance processing to output data having processed signals J′(x),
wherein:
J′(x) is a convergence value of J(x) in a case where M increases, J(x) being obtained according to the following Formulas 1 to 3:
i ( x,m )= I ( x )+ N ( x,m )× K   (Formula 1)

if i ( x,m )≥ T,j ( x,m )=1

if i ( x,m )< T,j ( x,m )=0  (Formula 2)

J
⁡

(
x
)

=

1
M

⁢

∑

m
=
1

M

⁢

j
⁡

(

x
,
m

)

(

Formula
⁢

⁢
3

)

where:
i(x,m) is a signal value after adding the noise strength K, j(x,m) is a binary signal obtained by comparing the signal value i(x,m) with a predetermined threshold value T, M is a number of branch paths for the input signals I(x), m is a parameter showing one of M branch paths and is an integer in the range from 1 to M, and N(x,m) is a random number noise corresponding to the branch path m of the pixel position x and has the range from 1 to 0;
a correlation coefficient showing a correlation between J′(x) and the detection target signal t(x) for the plurality of pixel positions x is a function C(K) of the noise strength K, and
the noise strength setting unit sets the noise strength K based on the function C(K).

2. The signal processing apparatus according to claim 1 , wherein the noise strength setting unit sets the noise strength K satisfying a condition that the function C(K) is a local maximum value.

3. The signal processing apparatus according to claim 1 , wherein the noise strength setting unit sets the noise strength K so that the correlation coefficient C(K) of a case where the predetermined stochastic resonance processing is performed is larger than the correlation coefficient C(K) of a case where the predetermined stochastic resonance processing is not performed.

4. The signal processing apparatus according to claim 1 , wherein the noise strength setting unit sets the noise strength K within a range higher than the noise strength K satisfying a condition that the correlation coefficient C(K) is a local maximum value and lower than the noise strength K in a case where the correlation coefficient C(K) becomes convergent at a fixed value.

5. The signal processing apparatus according to claim 1 , wherein the noise is white noise having an upper limit at the noise strength K set by the noise strength setting unit.

6. The signal processing apparatus according to claim 1 , wherein the noise is normal distribution noise having an upper limit at the noise strength K set by the noise strength setting unit.

7. The signal processing apparatus according to claim 1 , the processor further serving as a threshold value setting unit configured to set the threshold value T for quantizing used in the predetermined stochastic resonance processing for the input signals I(x), based on the input data and the detection target data.

8. The signal processing apparatus according to claim 1 , wherein:
the detection target data is prepared as a plurality of pieces of detection target data having different phases with respect to the pixel position;
the acquisition unit acquires the plurality of pieces of the detection target data;
the noise strength setting unit sets the noise strength K for each of the plurality of pieces of the detection target data; and
the stochastic resonance processing unit uses the respective noise strengths set by the noise strength setting unit to subject the input signals I(x) to the predetermined stochastic resonance processing; and
the processor further serving as a selection unit configured to compare a plurality of results of the predetermined stochastic resonance processing executed by the stochastic resonance processing unit to select one result.

9. The signal processing apparatus according to claim 1 , wherein the predetermined stochastic resonance processing is performed by using the following formula to calculate the processed data J′(x) obtained from the input data I(x),
if I ( x )> T,J ′( x )=1

if I ( x )< T−K,J ′( x )=0

if T−K<I ( x )< T,J ′( x )=1−( T−I ( x ))/ K.

10. The signal processing apparatus according to claim 1 , the processor further serving as a display control unit configured to display the result of the stochastic resonance processing executed by the stochastic resonance processing unit on a display apparatus.

11. The signal processing apparatus according to claim 1 , the processor further serving as a reading unit configured to read an image,
wherein the input data is image data of the reading result of the reading unit.

12. The signal processing apparatus according to claim 11 , the processor further serving as a printing unit configured to print an image,
wherein the reading unit reads the image printed by the printing unit.

13. A signal processing method, comprising:
an acquisition step of acquiring input data having input signals I(x) corresponding to a plurality of pixel position x respectively, and detection target data having de

Assignees

• Canon Kk

Inventors

• Tanaka Wakako
• Hori Shinjiro
• Suwa Tetsuya
• Ishikawa Tomokazu

Classifications

• G06K9/00986

  Physics · mapped topic

• H04N1/409 Primary

  Edge or detail enhancement; Noise or error suppression · CPC title

• G06K9/036

  Physics · mapped topic

• G06T7/0002 Primary

  Inspection of images, e.g. flaw detection · CPC title

• G06K9/6212

  Physics · mapped topic