Biological information detecting device

• US 7,965,874 B2
• Filed: 11/08/2005
• Issued: 06/21/2011
• Est. Priority Date: 05/15/2003
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Shinzaki, Takashi, Abiko, Yukihiro
• Primary Examiner(s): Ahmed; Samir A
• Assistant Examiner(s): PATEL, JAYESH A
• Application Number:
  US11/268,708
• Publication Number:
  US 20060056700A1
• Time in Patent Office: 2,051 Days
• Field of Search: 382124-126
• US Class Current: 382/116
• CPC Class Codes: G06T 7/66 of image moments or centre of gravity
• CPC Class Codes: G06V 10/993 Evaluation of the quality of the acquired pattern
• CPC Class Codes: G06V 40/1306 non-optical, e.g. ultrasonic or capacitive sensing
• CPC Class Codes: G06V 40/1347 Preprocessing; Feature extraction

Abstract

When an image representing biological information is input from a biological information input unit 10, such as a fingerprint sensor or the like, for obtaining an image representing biological information, such as a fingerprint or the like, statistical quantities, such as the mean value and standard deviation of the pixel values of the sampled image, are calculated. Then, using the statistical quantities, a region containing biological information is extracted, its sensitivity variations are eliminated and the effects of stains, such as a residual fingerprint is nullified, thereby generating a favorable biological image with high contrast.

Claims

1. A biological information detecting device, comprising:

a sensor configured to sample biological information;

a biological information region extraction unit configured to calculate statistical quantities, based on a value of pixel distribution of an image sampled by the sensor, and to extract a region containing biological information, based on the statistical quantities; and

a partial sensitivity fluctuation correction unit configured to correct partial sensitivity fluctuations by homogenizing the value of pixel levels of a background in each partial region of the sampled image, wherein

partial sensitivity fluctuations for each partial region are corrected by homogenizing the value of pixel levels of the background after homogenizing a mean value and standard deviation of the respective partial region when the standard deviation value of the respective partial region is not smaller than a standard deviation value of a total image whose sensitivity variations of each background image has been corrected, and, if the standard deviation value of the respective partial region is smaller than a standard deviation value of the total image whose sensitivity variations of each background image has been corrected, the partial sensitivity fluctuations for the respective partial region are not corrected by homogenizing standard deviation values for the respective partial region.

2. The biological information detecting device according to claim 1, wherein

said biological information region extraction unit extracts a range specified using a centroid of an image sampled by said sensor unit and a second order moment around the centroid, as a region containing biological information.

3. The biological information detecting device according to claim 1, further comprising

a sensitivity variations correction unit for correcting sensitivity variations of the sampled image, using a ratio of pixel values of the background image.

4. The biological information detecting device according to claim 1, further comprising

a sensitivity setting unit for setting a sensitivity used when sampling the biological information,

wherein a threshold value at which the respective numbers of pixels at value of pixel levels lower and higher than the specific threshold assume a predetermined ratio is set to a sensitivity obtained based on a background pixel value.

5. The biological information detecting device according to claim 1, further comprising

a pixel value correction unit whose upper value of pixel limit based on a maximum quantization level and lower value of pixel limit based on a minimum quantization level are a background value of pixel level of an extracted biological information region and a minimum value of the value of pixel level of the biological information region, respectively.

6. The biological information detecting device according to claim 1, further comprising

an image determination unit determining a state of the sampled image, based on a mean value and a standard deviation of the extracted biological information region.

7. The biological information detecting device according to claim 6, wherein

said image determination unit determines the state of the sampled image, based on a value obtained by normalizing the mean value and standard deviation of the extracted biological information region using a ratio between a sensitivity setting value of the sampled image and a sensitivity setting value of a background image.

8. The biological information detecting device according to claim 3, further comprising

a correction unit eliminating noise from the sampled image, wherein

a region containing biological information is extracted according to statistical information about a value of pixel distribution of a corrected image obtained from the said sensitivity variation correction unit.

9. The biological information detecting device according to claim 1, further comprising

a sensitivity adjustment unit setting a threshold value at which the respective numbers of pixels at values lower and higher than the specific threshold assume a predetermined ratio, to a sensitivity that coincides with a background brightness in a pixel value frequency distribution of a biological information region extracted by said biological information region extraction unit.

10. The biological information detecting device according to claim 1, further comprising:

a biological information determination unit that determines an existence/non-existence of biological information of a sampled image when the number of pixels in which two images consecutively sampled beyond a predetermined threshold value have different pixel values is substantially different from the number of pixels in said sensor, in an image group consecutively sampled using said sensor and does not determine an existence/non-existence of biological information of a sampled image when the number of pixels in which two images consecutively sampled beyond a predetermined threshold value have different pixel values almost equals the number of pixels in said sensor, in an image group consecutively sampled using said sensor; and

an unnecessary information elimination unit for eliminating unnecessary information from a sampled image, using a corrected image determined to contain no biological information.

11. A method for executing a biological information detecting method by a biological information detecting device, the method comprising:

sampling biological information;

calculating statistical quantities, based on a value of pixel distribution of an image sampled in the sampling, and extracting a region containing the biological information, based on the statistical quantities; and

correcting partial sensitivity fluctuations by homogenizing the value of pixel levels of a background in each partial region of the sampled image, wherein

partial sensitivity fluctuations for each partial region are corrected by homogenizing the value of pixel levels of the background after homogenizing a mean value and standard deviation of the respective partial region when the standard deviation value of the respective partial region is not smaller than a standard deviation value of a total image whose sensitivity variations of each background image has been corrected, and, if the standard deviation value of the respective partial region is smaller than a standard deviation value of the total image whose sensitivity variations of each background image has been corrected, the partial sensitivity fluctuations for the respective partial region are not corrected by homogenizing standard deviation values for the respective partial region.