Image pickup method and image pickup apparatus

An image pickup method using an image pickup apparatus including a charge coupled device (CCD) image pickup device, a first acquisition unit for acquiring an image signal outputted from effective pixels of a light-receiving face of the CCD image pickup device, a second acquisition unit for acquiring a signal outputted from shaded pixels of at least one of upper, lower, left, and right portions of the light-receiving face of the CCD image pickup device, an automatic gain control unit, a calculation unit for calculating a representative value of the signal outputted from the shaded pixels acquired by the second acquisition unit, a screen memory for storing a dark current component outputted from the effective pixels acquired by the first acquisition unit, a line memory for storing an effective pixel signal outputted from the effective pixels acquired by the first acquisition unit, and a subtraction unit for performing a variable gain amplification of the stored dark current component outputted from the effective pixels and subtracting it from the effective pixel signal, the method comprising:

• controlling, based on a vertical period of the representative value of the signal outputted from the shaded pixels, a variable gain amplification of the vertical period of the dark current component of the effective pixel signal to subtract it from the effective pixel signal;
• and
• controlling a variable gain amplification of the effective pixel signal in plus correlation with a recursive average between screens of the representative value.

An image pickup method using an image pickup apparatus including an electron multiplying-charge coupled device (CCD) image pickup device, a first acquisition unit for acquiring an image signal outputted from effective pixels of a light-receiving face of the CCD image pickup device, a second acquisition unit for acquiring a signal outputted from shaded pixels of at least one of upper, lower, left, and right portions of the light-receiving face of the CCD image pickup device, an automatic gain control unit, a calculation unit for calculating a representative value of the signal outputted from the shaded pixels acquired by the second acquisition unit, a screen memory for storing a dark current component outputted from the effective pixels acquired by the first acquisition unit, a line memory for storing an effective pixel signal outputted from the effective pixels acquired by the first acquisition unit, a subtraction unit for performing a variable gain amplification of the stored dark current component outputted from the effective pixels and subtracting it from the effective pixel signal, and a variable voltage electron multiplying electrode driving unit, the method comprising:

• performing at least one of controlling, based on a vertical period of the representative value, a variable gain amplification of the vertical period of the dark current component of the effective pixel signal to subtract it from the effective pixel signal, and controlling a variable gain amplification of a horizontal period of the dark current component of the effective pixel signal, in plus correlation with a ratio between a value of the horizontal period of the representative value and an average above the vertical period of the representative value or a ratio between a recursive average in screens of the representative value and the average above the vertical period of the representative value, to subtract it from the effective pixel signal;
• multiplying a ratio between a present value of the representative value of the signal outputted from the shaded pixels acquired by the second acquisition unit and an assumption value of the dark current which is obtained by correcting, with a temperature detected by the image pickup device, the representative value of the signal outputted from the shaded pixels acquired by the second acquisition unit and stored at as low electron multiplying electrode voltage as the electron multiplication is not performed by a reference dark current of the effective pixels stored when a non-electron multiplication was performed to subtract it from the effective pixel signal.

An image pickup method using an image pickup apparatus including a charge coupled device (CCD) image pickup device, a first acquisition unit for acquiring an image signal outputted from effective pixels of a light-receiving face of the CCD image pickup device, a second acquisition unit for acquiring a signal outputted from shaded pixels of at least one of upper, lower, left, and right portions of the light-receiving face of the CCD image pickup device, an automatic gain control unit, a calculation unit for calculating a representative value of the signal outputted from the shaded pixels acquired by the second acquisition unit, a screen memory for storing a dark current component outputted from the effective pixels acquired by the first acquisition unit, a line memory for storing an effective pixel signal outputted from the effective pixels acquired by the first acquisition unit, a subtraction unit for performing a variable gain amplification of the stored dark current component outputted from the effective pixels and subtracting it from the effective pixel signal, and a control unit for controlling accumulation time, wherein the screen memory further stores the effective pixel signal outputted from the effective pixels acquired by the first acquisition unit, the method comprising:

• controlling a variable gain amplification of a horizontal period of the dark current component of the effective pixel signal, in plus correlation with a ratio between a value of the horizontal period of the representative value of the signal outputted from the shaded pixels and an average above a vertical period of the representative value or a ratio between a recursive average in screens of the representative value and the average above the vertical period of the representative value, to subtract it from the effective pixel signal;
• and
• controlling the accumulation time in plus correlation with a recursive average between screens of the representative value.

An image pickup method using an image pickup apparatus including an electron multiplying-charge coupled device (CCD) image pickup device, a variable voltage electron multiplying electrode driving unit, a first acquisition unit for acquiring an image signal outputted from effective pixels of a light-receiving face of the CCD image pickup device, a second acquisition unit for acquiring a signal outputted from shaded pixels of at least one of upper, lower, left, and right portions of the light-receiving face of the CCD image pickup device, an automatic gain control unit, a calculation unit for calculating a representative value of the signal outputted from the shaded pixels acquired by the second acquisition unit, a line memory for storing an effective pixel signal outputted from the effective pixels acquired by the first acquisition unit, and a screen memory for storing an effective pixel signal outputted from the effective pixels acquired by the first acquisition unit, the method comprising:

• comparing a square integral of difference of correlated portions between scanning line signals and a square integral of an error of averages of the correlated portions between the scanning line signals which represents a sum of a square integral of a ratio of averages of the correlated portions between the scanning line signals and a square integral of a difference of averages of the correlated portions between the scanning line signals;
• performing at least any one of increasing an average variable gain amplification above a vertical period, decreasing a variable gain amplification of the vertical period of the effective pixel signal, decreasing a variable gain amplification of a horizontal period of the effective pixel signal, and decreasing an average electron multiplying electrode amplitude value above the vertical period, such that the square integral of difference of the correlated portions between the scanning line signals becomes to equal the square integral of the error of averages of the correlated portions between the scanning line signals.

An image pickup method using an image pickup apparatus including an electron multiplying-charge coupled device (CCD) image pickup device, a variable voltage electron multiplying electrode driving unit, a first acquisition unit for acquiring an image signal outputted from effective pixels of a light-receiving face of the CCD image pickup device, a second acquisition unit for acquiring a signal outputted from shaded pixels of at least one of upper, lower, left, and right portions of the light-receiving face of the CCD image pickup device, an automatic gain control unit, a calculation unit for calculating a representative value of the signal outputted from the shaded pixels acquired by the second acquisition unit, a screen memory for storing a dark current component outputted from the effective pixels acquired by the first acquisition unit, a line memory for storing an effective pixel signal outputted from the effective pixels acquired by the first acquisition unit, a subtraction unit for performing a variable gain amplification of the stored dark current component outputted from the effective pixels and subtracting it from the effective pixel signal, a temperature measuring unit, a noise removing unit, and a 14-bit or higher analog digital converter, the method comprising:

• comparing, when electron multiplication is performed, correlations of a non-recursive average component of an image signal of a present scanning line with a non-recursive average component of an image signal of a scanning line of a previous screen, a non-recursive average component of an image signal of a scanning line before 1H of the previous screen, and a non-recursive average component of an image signal of a scanning line after 1H of the previous screen;
• and
• performing at least any one of calculating accumulation of a square of a ratio between non-recursive average components having high correlations, calculating accumulation of a square of a difference between non-recursive average components having high correlations, calculating a ratio between the accumulation of the square of the ratio and the accumulation of the square of the difference, controlling an intra-screen average value of a variable gain amplification and electron multiplying electrode amplitude such that the ratio becomes greater than a predetermined value, and uniformly controlling a predetermined level of an image signal;
• calculating a ratio between a low frequency component level and a high frequency component level of the square of the difference between non-recursive average components having high correlations, controlling the intra-screen average value of the variable gain amplification and the electron multiplying electrode amplitude such that the ratio becomes greater than the predetermined value, and uniformly controlling the predetermined level of the image signal;
• and calculating a ratio between a value of a present variable gain amplification and an assumption value of the electron multiplication, controlling the intra-screen average value of the variable gain amplification and the electron multiplying electrode amplitude such that the ratio becomes greater than the predetermined value, and uniformly controlling the predetermined level of the image signal.

An image pickup method using an image pickup apparatus including a charge coupled device (CCD) image pickup device, a first acquisition unit for acquiring an image signal outputted from effective pixels of a light-receiving face of the CCD image pickup device, a second acquisition unit for acquiring a signal outputted from a horizontal-optical black (H-OB) of shaded pixels of at least one of left and right portions of the light-receiving face of the CCD image pickup device, a calculation unit for calculating a representative value of the signal outputted from the H-OB of the shaded pixels acquired by the second acquisition unit, a screen memory for storing a dark current component outputted from the effective pixels acquired by the first acquisition unit, a line memory for storing an effective pixel signal outputted from the effective pixels acquired by the first acquisition unit, a subtraction unit for performing a variable gain amplification of the stored dark current component outputted from the effective pixels and subtracting it from the effective pixel signal, a front end processor (FEP) containing a correlated double sampling unit for removing a noise from a signal outputted from the CCD image pickup device, an automatic gain control unit for adjusting gain of a signal, and an analog digital converter for converting to digital image signal Vi, and a digital image signal processing circuit, the method comprising:

• in the digital image signal processing circuit, setting as a H-OB representative value an average of M-N number of H-OB excluding the upper N among M number of H-OB;
• subtracting the H-OB representative value from an effective pixel signal of a corresponding line;
• and
• controlling a variable gain amplification of the FEP in minus correlation with a ratio between the H-OB representative value and an average above a vertical period of the H-OB representative value or a ratio between a recursive average within the vertical period of the H-OB representative value and an average above the vertical period of the H-OB representative value.

An image pickup apparatus comprising:

• a charge coupled device (CCD) image pickup device;
• a first acquisition unit for acquiring an image signal outputted from effective pixels of a light-receiving face of the CCD image pickup device;
• a second acquisition unit for acquiring a signal outputted from shaded pixels of at least one of upper, lower, left, and right portions of the light-receiving face of the CCD image pickup device;
• an automatic gain control unit;
• a calculation unit for calculating a representative value of the signal outputted from the shaded pixels acquired by the second acquisition unit;
• a screen memory for storing a dark current component outputted from the effective pixels acquired by the first acquisition unit;
• a line memory for storing an effective pixel signal outputted from the effective pixels acquired by the first acquisition unit;
• a subtraction unit for performing a variable gain amplification of the stored dark current component outputted from the effective pixels and subtracting it from the effective pixel signal;
• and
• at least any one of groups including:
• a first group containing a control unit for controlling a variable gain amplification above a vertical period of the effective pixel signal in plus correlation with an average above the vertical period of the representative value of the signal outputted from the shaded pixels, and a control unit for controlling a variable gain amplification of a horizontal period of the effective pixel signal in minus correlation with a ratio between a value of the horizontal period of the representative value and the average above the vertical period of the representative value or a ratio between a recursive average in screens of the representative value and the average above the vertical period of the representative value;
• a second group containing a subtraction unit for controlling, based on a vertical period of the representative value of the signal outputted from the shaded pixels, a variable gain amplification of the vertical period of the dark current component of the effective pixel signal to subtract it from the effective pixel signal, and a control unit for controlling a variable gain amplification of the effective pixel signal in plus correlation with a recursive average between screens of the representative value;
• a third group containing a subtraction unit for multiplying a ratio between a present value of the representative value of the signal outputted from the shaded pixels acquired by the second acquisition unit and an assumption value of the dark current which is obtained by correcting, with a temperature detected by the image pickup device, the representative value of the signal outputted from the shaded pixels acquired by the second acquisition unit and stored at as low electron multiplying electrode voltage as the electron multiplication is not performed by a reference dark current of the effective pixels stored when a non-electron multiplication was performed to subtract it from the effective pixel signal, and at least one of a subtraction unit for controlling, based on a vertical period of the representative value, a variable gain amplification of the vertical period of the dark current component of the effective pixel signal to subtract it from the effective pixel signal, and a subtraction unit for controlling a variable gain amplification of a horizontal period of the dark current component of the effective pixel signal, in plus correlation with a ratio between a value of the horizontal period of the representative value and an average above the vertical period of the representative value or a ratio between a recursive average in screens of the representative value and the average above the vertical period of the representative value, to subtract it from the effective pixel signal;
• a fourth group containing the screen memory for further storing the effective pixel signal outputted from the effective pixels acquired by the first acquisition unit, a control unit for controlling accumulation time, a subtraction unit for controlling a variable gain amplification of a horizontal period of the dark current component of the effective pixel signal, in plus correlation with a ratio between a value of the horizontal period of the representative value of the signal outputted from the shaded pixels and an average above a vertical period of the representative value or a ratio between a recursive average in screens of the representative value and the average above the vertical period of the representative value, to subtract it from the effective pixel signal, and a control unit for controlling the accumulation time in plus correlation with a recursive average between screens of the representative value;
• a fifth group containing the screen memory for further storing the effective pixel signal outputted from the effective pixels acquired by the first acquisition unit, an electron multiplying-CCD image pickup device, a variable voltage electron multiplying electrode driving unit, a control unit for comparing a square integral of difference of correlated portions between scanning line signals and a square integral of an error of averages of the correlated portions between the scanning line signals which represents a sum of a square integral of a ratio of averages of the correlated portions between the scanning line signals and a square integral of a difference of averages of the correlated portions between the scanning line signals and increasing an average variable gain amplification above a vertical period such that the square integral of difference of the correlated portions between the scanning line signals becomes to equal the square integral of the error of averages of the correlated portions between the scanning line signals, a control unit for decreasing a variable gain amplification of the vertical period of the effective pixel signal, a control unit for decreasing a variable gain amplification of a horizontal period of the effective pixel signal, and a control unit for decreasing an average electron multiplying electrode amplitude value above the vertical period;
• a sixth group containing the electron multiplying-charge coupled device (CCD) image pickup device, the variable voltage electron multiplying electrode driving unit, a temperature measuring unit, a noise removing unit, a 14-bit or higher analog digital converter, a comparing unit for comparing, when electron multiplication is performed, correlations of a non-recursive average component of an image signal of a present scanning line with a non-recursive average component of an image signal of a scanning line of a previous screen, a non-recursive average component of an image signal of a scanning line before 1H of the previous screen, and a non-recursive average component of an image signal of a scanning line after 1H of the previous screen, a calculation unit for calculating accumulation of a square of a ratio between non-recursive average components having high correlations, a calculation unit for calculating accumulation of a square of a difference between non-recursive average components having high correlations, a calculation unit for calculating a ratio between the accumulation of the square of the ratio and the accumulation of the square of the difference, a control unit for controlling an intra-screen average value of a variable gain amplification and electron multiplying electrode amplitude such that the ratio becomes greater than a predetermined value, and a control unit for uniformly controlling a predetermined level of an image signal;
• a seventh group containing the electron multiplying-charge coupled device (CCD) image pickup device, the variable voltage electron multiplying electrode driving unit, the temperature measuring unit, the noise removing unit, the 14-bit or higher analog digital converter, a comparing unit for comparing, when electron multiplication is performed, correlations of a non-recursive average component of an image signal of a present scanning line with a non-recursive average component of an image signal of a scanning line of a previous screen, a non-recursive average component of an image signal of a scanning line before 1H of the previous screen, and a non-recursive average component of an image signal of a scanning line after 1H of the previous screen, a calculation unit for calculating accumulation of a square of a ratio between non-recursive average components having high correlations, a calculation unit for calculating a ratio between a low frequency component level and a high frequency component level of the square of the difference between non-recursive average components having high correlations, a control unit for controlling the intra-screen average value of the variable gain amplification and the electron multiplying electrode amplitude such that the ratio becomes greater than the predetermined value, and a control unit for uniformly controlling the predetermined level of the image signal;
• an eighth group containing the electron multiplying-charge coupled device (CCD) image pickup device, the variable voltage electron multiplying electrode driving unit, the temperature measuring unit, the noise removing unit, the 14-bit or higher analog digital converter, a comparing unit for comparing, when electron multiplication is performed, correlations of a non-recursive average component of an image signal of a present scanning line with a non-recursive average component of an image signal of a scanning line of a previous screen, a non-recursive average component of an image signal of a scanning line before 1H of the previous screen, and a non-recursive average component of an image signal of a scanning line after 1H of the previous screen, a calculation unit for calculating a ratio between a value of a present variable gain amplification and an assumption value of the electron multiplication, a control unit for controlling the intra-screen average value of the variable gain amplification and the electron multiplying electrode amplitude such that the ratio becomes greater than the predetermined value, and a control unit for uniformly controlling the predetermined level of the image signal;
• a ninth group containing a front end processor (FEP) having a correlated double sampling unit for removing a noise from a signal outputted from the CCD image pickup device having a horizontal-optical black (H-OB), an automatic gain control unit for adjusting gain of a signal, and an analog digital converter for converting to digital image signal Vi, and a digital image signal processing circuit, wherein the digital image signal processing circuit has a subtraction unit for setting as a H-OB representative value an average of M-N number of H-OB excluding the upper N among M number of H-OB and subtracting the H-OB representative value from an effective pixel signal of a corresponding line, and a control unit for controlling a variable gain amplification of the FEP in minus correlation with a ratio between the H-OB representative value and an average above a vertical period of the H-OB representative value or a ratio between a recursive average within the vertical period of the H-OB representative value and an average above the vertical period of the H-OB representative value.

An image pickup method using an image pickup apparatus including a charge coupled device (CCD) image pickup device, a first acquisition unit for acquiring an image signal outputted from effective pixels of a light-receiving face of the CCD image pickup device, a second acquisition unit for acquiring a signal outputted from shaded pixels of at least one of upper, lower, left, and right portion of the light-receiving face of the CCD image pickup device, an automatic gain control unit, a calculation unit for calculating a representative value of the signal outputted from the shaded pixels acquired by the second acquisition unit, a screen memory for storing a dark current component outputted from the effective pixels acquired by the first acquisition unit, a line memory for storing an effective pixel signal outputted from the effective pixels acquired by the first acquisition unit, and a subtraction unit for performing a variable gain amplification of the stored dark current component of the effective pixel signal and subtracting it from the effective pixel signal, the method comprising:

• performing at least one of controlling a variable gain amplification of the effective pixel signal in correlation with the representative value, and controlling a variable gain amplification of the stored dark current component of the effective pixel signal, in plus correlation with the representative value, to subtract it from the effective pixel signal.

The image pickup apparatus, comprising:

• an electron multiplying-charge coupled device (CCD) image pickup device;
• a first acquisition unit for acquiring an image signal outputted from effective pixels of a light-receiving face of the CCD image pickup device;
• a second acquisition unit for acquiring a signal outputted from shaded pixels of at least one of upper, lower, left, and right portions of the light-receiving face of the CCD image pickup device;
• an automatic gain control unit;
• a calculation unit for calculating a representative value of the signal outputted from the shaded pixels acquired by the second acquisition unit;
• a screen memory for storing a dark current component outputted from the effective pixels acquired by the first acquisition unit;
• a line memory for storing an effective pixel signal outputted from the effective pixels acquired by the first acquisition unit;
• a subtraction unit for performing a variable gain amplification of the stored dark current component outputted from the effective pixels and subtracting it from the effective pixel signal;
• a variable voltage electron multiplying electrode driving unit;
• a temperature measuring unit;
• a noise removing unit;
• a 14-bit or higher analog digital converter;
• a correlation comparison unit for comparing, when electron multiplication is performed, correlations of a non-recursive average component of an image signal of a present scanning line with a non-recursive average component of an image signal of a scanning line of a previous screen, a non-recursive average component of an image signal of a scanning line before 1H of the previous screen, and a non-recursive average component of an image signal of a scanning line after 1H of the previous screen;
• a first accumulation unit for calculating accumulation of a square of a ratio between non-recursive average components having high correlations;
• a second accumulation unit for calculating accumulation of a square of a difference between non-recursive average components having high correlations;
• at least any one of a first ratio calculation unit for calculating a ratio between the accumulation of the square of the ratio and the accumulation of the square of the difference, a second ratio calculation unit for calculating a ratio between a low frequency component level and a high frequency component level of the square of the difference between non-recursive average components having high correlations, and a third ratio calculation unit for calculating a ration between the value of the present variable gain amplification and the assumption value of the electron multiplication;
• a first control unit for controlling an intra-screen average value of a variable gain amplification and electron multiplying electrode amplitude such that the ratio becomes greater than a predetermined value;
• and
• a second control unit for uniformly controlling a predetermined level of an image signal.