Image processing apparatus, image processing method and image pickup apparatus

An image processing apparatus comprising:

• an image signal capturing device which captures color signals for each pixel;
• a level information calculating device which calculates the level information of each pixel from the color signal;
• a filtering device which filters the level information of a pixel to be processed using the level information of pixels in an area peripheral to the pixel to be processed;
• a gain calculating device which calculates a gain by which the color signal of the pixel to be processed is multiplied based on a reference value obtained by filtering the level information;
• and
• a multiplying device which multiplies the color signals of each pixel by the gain.

An image processing apparatus comprising:

• an area discriminating device which discriminates an area using pixels in an area peripheral to a pixel to be processed;
• a filtering device which filters the level information of the pixel to be processed using the level information discriminated by the area discriminating device;
• a gain calculating device which calculates a gain by which the color signal of the pixel to be processed is multiplied based on a reference value obtained by filtering the level information;
• and
• a multiplying device which multiplies the color signals of each pixel by the gain.

An image processing apparatus comprising:

• an image signal capturing device which captures color signals for each pixel;
• a level information calculating device which calculates the level information of each pixel from the color signal;
• a final gradation conversion device which calculates an output with the level information input from the level information calculating device as an input using an undistorted final gradation conversion curve representing a relationship of input and output in the case where the color signals are multiplied by a predetermined gain to perform a dynamic range compression process and subjected to a gradation conversion processing according to a predetermined gradation conversion curve;
• a gain calculating device which inversely calculates a gain from the output calculated by the final gradation conversion device and the predetermined gradation conversion curve at the time of the gradation conversion processing;
• and
• a multiplying device which multiplies the color signals of each pixel by the gain.

An image processing method comprising:

• an image signal capturing step for capturing color signals for each pixel;
• a level information calculating step for calculating the level information of each pixel from the color signal;
• a gain calculating step for calculating the level information of each pixel by performing a weighted addition to the color signal to increase the ratio of a color signal the level of which is high among the color signals;
• a multiplying step for multiplying the color signals of each pixel by the gain.

An image processing method comprising:

• an image signal capturing step for capturing color signals for each pixel;
• a level information calculating step for calculating the level information of each pixel from the color signal;
• a filtering step for filtering the level information of a pixel to be processed using the level information of pixels in an area peripheral to the pixel to be processed;
• a gain calculating step for calculating a gain by which the color signal of the pixel to be processed is multiplied based on a reference value obtained by filtering the level information;
• and
• a multiplying step for multiplying the color signals of each pixel by the gain.

An image processing method comprising:

• an area discriminating step for discriminating an area using pixels in an area peripheral to a pixel to be processed;
• a filtering step for filtering the level information of the pixel to be processed using the level information discriminated at the area discriminating step;
• a gain calculating step for calculating a gain by which the color signals of the pixel to be processed are multiplied based on a reference value obtained by filtering the level information;
• and
• a multiplying step for multiplying the color signals of each pixel by the gain.

An image processing method comprising the steps of:

• an image signal capturing step for capturing color signals for each pixel;
• a level information calculating step for calculating the level information of each pixel from the color signal;
• a final gradation conversion step for calculating an output with the level information input at the level information calculating step as an input using an undistorted final gradation conversion curve representing a relationship of input and output in the case where the color signals are multiplied by a predetermined gain to perform a dynamic range compression process and subjected to a gradation conversion processing according to a predetermined gradation conversion curve;
• a gain calculating step for inversely calculating a gain from the output calculated at the final gradation conversion step and the predetermined gradation conversion curve at the time of the gradation conversion processing;
• and
• a multiplying step for multiplying the color signals of each pixel by the gain.