Imaging apparatus offering dynamic range that is expandable by weighting two image signals produced during different exposure times with two coefficients whose sum is 1 and adding them up

An imaging apparatus comprising:

• an imaging device for successively outputting a first image signal produced by imaging an object during a first exposure time, and a second image signal that has a saturation value relative to a higher light level than said first image signal;
• a picture signal producing device composed of:
• first and second weighting circuits for applying a first weight, which decreases monotonously with an increase in light level from a light level of substantially no luminance up to a light level causing said first and second image signals to have the saturation value, and a second weight, which increases monotonously from said light level of substantially no luminance up to said light level causing said first and second image signals to have said saturation value, to said first and second image signals under the condition that the sum of said first and second weights is 1;
• and
• an adding circuit for adding together first and second picture signals produced by applying said first and second weights to said first and second image signals by means of said first and second weighting circuits;
• and
• a signal processing circuit for processing a picture signal output from said adding circuit and producing a video signal according to which an image can be displayed on a display.

An imaging apparatus comprising:

• an imaging device for successively outputting a first image signal produced by imaging an object during a first exposure time, and a second image signal that has a saturation value relative to a higher light level than said first image signal;
• a picture signal producing device composed of:
• first and second weighting circuits for applying a first weight, which decreases monotonously with an increase in light level up to a light level causing said first and second image signals to have a saturation value, and a second weight, which increases monotonously therewith, to said first and second image signals under the condition that the sum of said first and second weights is 1;
• and
• an adding circuit for adding together first and second picture signals produced by applying said first and second weights to said first and second image signals by means of said first and second weighting circuits;
• and
• a signal processing circuit for processing a picture signal output from said adding circuit and producing a video signal according to which an image can be displayed on a display;
• wherein
• said first weight function F1(x) is cos2(px) where x is a light level and p is a coefficient, and said second weight function F2(x) is sin2(px).

An endoscopic imaging apparatus, comprising:

• an endoscope having an elongated insertion unit, irradiating illumination light to an object through an illumination window located at the distal end of said insertion unit, and including an imaging device for successively outputting a first image signal produced by imaging said object illuminated with said illumination light during a first exposure time, and a second image signal that has a saturation value relative to a higher light level than said first image signal;
• an image signal producing circuit composed of:
• first and second weighting circuits for applying a first weight, which decreases monotonously with an increase in light level from a light level of substantially no luminance up to a light level causing said first and second image signals to have the saturation value, and a second weight, which increases monotonously from said light level of substantially no luminance up to said light level causing said first and second image signals to have said saturation value, to said first and second image signals under the condition that the sum of said first and second weights is 1;
• and
• an adding circuit for adding together first and second picture signals produced by applying said first and second weights to said first and second image signals by means of said first and second weighting circuits;
• a signal processing circuit for processing a picture signal output from said adding circuit and producing a video signal which can be displayed;
• and
• a display for displaying a synthetic image represented by said picture signal when inputting said video signal.

An imaging apparatus, comprising:

• an imaging device for successively outputting a first image signal produced by imaging an object during a first exposure time, and a second image signal that is produced by imaging said object during a second exposure time shorter than said first exposure time and that has a saturation value relative to a higher light level than said first image signal;
• a picture signal producing circuit composed of:
• first and second weighting circuits for applying a first weight, which decreases monotonously with an increase in light level from a light level of substantially no luminance up to a light level causing said first and second image signals to have the saturation value, and a second weight, which increases monotonously from said light level of substantially no luminance up to said light level causing said first and second image signals to have said saturation value, to said first and second image signals under the condition that the sum of said first and second weights is 1;
• and
• an adding circuit for adding together first and second picture signals produced by applying said first and second weights to said first and second image signals by means of said first and second weighting circuits;
• and
• a signal processing circuit for processing a picture signal output from said adding circuit and producing a video signal according to which an image can be displayed on a display.

An imaging apparatus, comprising:

• an imaging device for successively outputting a first image signal produced by imaging an object during a first exposure time, and a second image signal that has a saturation value relative to a higher light level than said first image signal;
• a picture signal producing circuit composed of:
• first and second weighting circuits for applying a first weight, which decreases monotonously with an increase in light level from a light level of substantially no luminance up to a light level causing said first and second image signals to have the saturation value, and a second weight, which increases monotonously from said light level of substantially no luminance up to said light level causing said first and second image signals to have said saturation value, to said first and second image signals under the condition that the sum of said first and second weights is 1;
• and
• an adding circuit for adding together first and second picture signals produced by applying said first and second weights to said first and second image signals by means of said first and second weighting circuits;
• and
• a signal processing circuit for processing a picture signal output from said adding circuit and producing a video signal according to which an image can be displayed on a display.

An imaging apparatus, comprising:

• an imaging device for successively outputting a first image signal produced by imaging an object during a first exposure time, and a second image signal that has a saturation value relative to a higher light level than said first image signal;
• a picture signal producing circuit composed of:
• first and second weighting circuits for applying a first weight, which decreases monotonously with an increase in light level from a light level of substantially no luminance up to a light level causing said first and second image signals to have the saturation value, and a second weight, which increases monotonously from said light level of substantially no luminance up to said light level causing said first and second image signals to have said saturation value, to said first and second image signals under the condition that the sum of said first and second weights is 1;
• and
• an adding circuit for adding together picture signals produced by applying said first and second weights to said first and second image signals by means of said first and second weighting circuits;
• and
• a signal processing circuit for processing a picture signal output from said adding circuit and producing a video signal according to which an image can be displayed on a display.