Image apparatus and method for compensating for high and low luminance image portions via exposure control and gamma correction

An image processing method comprising:

• an image input step of receiving image signals;
• a detecting step of detecting at least high-luminance object signals contained in the image signals received by the image input step, wherein the detecting step generates a histogram by calculating the number of pixels for each luminance level on the basis of the image signals and calculates the high-luminance object signals by integrating the pixels falling in a high-luminance frame and low-luminance object signals by integrating the pixels falling in a low-luminance frame;
• an automatic exposure control step of controlling an exposure amount to be used for an imaging operation in accordance with the high-luminance object signals detected by the detecting step based on a comparison of the integration over the high-luminance frame and the low-luminance frame of the histogram;
• and
• a gamma correction step of controlling a gamma correction amount for the image signals received on the basis of the exposure amount controlled by the automatic exposure control step and the degree of concentration of pixels in a minimum-luminance range detected in the histogram so that the luminance levels of the pixels in the low-luminance frame are raised and distributed to include a medium-luminance range;
• wherein the gamma correction amount is performed in real time in accordance with an object condition in the image signals.

A camera apparatus comprising:

• image input unit for receiving image signals;
• a detecting unit for detecting at least high-luminance object signals contained in the image signals received by the image input unit, wherein the detecting unit generates a histogram by calculating the number of pixels for each luminance level on the basis of the image signals and calculates the high-luminance object signals by integrating the pixels falling in a high-luminance frame and low-luminance object signals by integrating the pixels falling in a low-luminance frame;
• an automatic exposure control unit for controlling an exposure amount to be used for an imaging operation in accordance with the high-luminance object signals detected by the detecting unit based on a comparison of the integration over the high-luminance frame and the low-luminance frame of the histogram;
• and
• a gamma correction unit for controlling a gamma correction amount for the image signals received on the basis of the exposure amount controlled by the automatic exposure control unit and the degree of concentration of pixels in a minimum-luminance range detected in the histogram so that the luminance levels of the pixels in the low-luminance frame are raised and distributed to include a medium-luminance range;
• wherein the gamma correction amount is performed in real time in accordance with an object condition in the image signals.

An automatic exposure control method of a camera apparatus, comprising:

• an image input step of receiving image signals;
• a detecting step of detecting at least high-luminance object signals contained in the image signals received by the image input step, wherein the detecting unit generates a histogram by calculating the number of pixels for each luminance level on the basis of the image signals and calculates the high-luminance object signals by integrating the pixels falling in a high-luminance frame and low-luminance object signals by integrating the pixels falling in a low-luminance frame;
• an automatic exposure control step of controlling an exposure amount to be used for an imaging operation in accordance with the high-luminance object signals detected by the detecting step based on a comparison of the integration over the high-luminance frame and the low-luminance frame of the histogram;
• and
• a gamma correction step of controlling a gamma correction amount for the image signals received on the basis of the exposure amount controlled by the automatic exposure control step and the degree of concentration of pixels in a minimum-luminance range detected in the histogram so that the luminance levels of the pixels in the low low-luminance frame are raised and distributed to include a medium-luminance range;
• wherein the gamma correction amount is performed in real time in accordance with an object condition in the image signals.

An image processing apparatus comprising:

• an image input unit for receiving image signals;
• a detecting unit for detecting at least high-luminance object signals contained in the image signals received by the image input unit, wherein the detecting unit generates a histogram by calculating the number of pixels for each luminance level on the basis of the image signals and calculates the high-luminance object signals by integrating the pixels falling in a high-luminance frame and low-luminance object signals by integrating the pixels falling in a low-luminance frame;
• an automatic exposure control unit for controlling an exposure amount to be used for an imaging operation in accordance with the high-luminance object signals detected by the detecting unit based on a comparison of the integration over the high-luminance frame and the low-luminance frame of the histogram;
• and
• a gamma correction unit for controlling a gamma correction amount for the image signals received on the basis of the exposure amount controlled by the automatic exposure control unit and the degree of concentration of pixels in a minimum-luminance range detected in the histogram so that the luminance levels of the pixels in the low-luminance frame are raised non-linearly and distributed to include a medium-luminance range;
• wherein the gamma correction circuit corrects the low-luminance in real time by determining the distribution of low-luminance image signals in the received image signals, identifying portions of the distribution of low-luminance image signals, adjusting the luminance of the image signals by increasing the gradation between low-luminance image signals in the identified portions of the distribution, and reducing the gradation between luminance image signals in non-identified portions.