In a method for generating color image signals derived from an array of color image pixels, the array of color pixels are subsampled in order to generate an array of subsampled color pixels. An array of new, evenly spaced color pixels are interpolated from the subsampled color pixels using surrounding pixels of the same color, and the color image signals derived from the array of new color pixels are subsequently processed, e.g., in a color filter array interpolation. By providing this correction in a preprocessing step, the rest of the normal image processing hardware or software may be used on the resultant subsampled CFA image without developing the characteristic blocky and wavy artifacts caused by an irregular subsampling pattern.
To eliminate an amplitude difference between luminance signals from pixels included in horizontal lines of color filters, caused by a sensitivity difference from one photosensor to another in a CCD, and reduce a horizontal stripe-like noise appearing in a monitoring image and captured image, there is provided an arithmetic circuit to calculate an amplitude difference in Gr and Gb signals based on an output from a four-channel detector to set gains multiplied by compensation factors, respectively, with which the white balance-processed Gr and Gb signals are equal in amplitude to each other, thereby controlling the gain of a while balance amplifier.
An apparatus and method for multispectral imaging comprising an array of filters in a mosaic pattern, a sensor array and an acquisition and processing module. The sensor array being disposed to receive an image that has been filtered by the array of filters. The acquisition and processing module processes the output of the sensor array (or mosaic acquired data) to provide a processed image. The acquisition and processing module processes the mosaic acquired data by performing first interpolation on the mosaic acquired data by the sensor array to provide a first approximation and performing second interpolation on the values of the first approximation to provide a second approximation.
An image signal processing method and an image signal processing apparatus for processing the color component signal obtained from a solid-state image pickup device including an arrangement of a plurality of photoelectric elements and a color filter arranged in the light receiving section of each pixel corresponding to the photoelectric element, an image signal generating apparatus and a computer program product for the image signal processing method. A color component signal is fetched from a designated pixel corresponding to the photoelectric element having a filter that can transmit the green light on a line of the solid-state image pickup device. A color component signal is also fetched from a pixel corresponding to the photoelectric element having a filter for transmitting at least the green light on another line, which pixel is located in the neighborhood of the designated pixel. Further, based on a plurality of the color signals fetched in the foregoing steps, the value of the color component signal of the designated pixel having the filter for transmitting at least the green light is determined.
The apparatus and method invented are operating upon a digital image signal obtained from an image sensor. The sensor is covered with different colored filters and is only able to record the color transmitted through each specific filter into the photosite or pixel. This type of sensor is known as a color filter array or CFA sensor. The different colored filters are arranged in a predefined pattern across the sensor. To obtain a full color image the missing color information is estimated by a set of weighed values obtained by an inverted gradient function. The set of weighted values is found from the neighboring pixels in the four compass directions, north, east, west and south or is found horizontally and vertically. The surrounding pixels are corrected by the chrominance channel to better fit the center pixel in the luminance channel, prior to using the gradient functions. The chrominance channel is interpolated in a similar manner and is also corrected to better fit the center pixel before the inverted gradient functions are applied.
An image pickup apparatus has an image sensor having first-type, second-type, and third-type pixels each producing a signal corresponding to a first, a second, and a third color respectively. The pixels are arranged in a two-dimensional array consisting of first-type and second-type lines arranged alternately, with the first-type lines each composed of first-type and second-type pixels arranged alternately and the second-type lines each composed of first-type and third-type pixels arranged alternately. The image pickup apparatus also has a first subtracter for calculating the difference between the outputs of the first-type pixels and the outputs of the second-type pixels on the first-type lines, and a second subtracter for calculating the difference between the outputs of the first-type pixels and the output of the third-type pixels on the second-type lines. The image pickup apparatus further has a control circuit, which sets the read-operation clock signal of the image sensor at a lower rate during actual shooting than during previewing when the difference between the absolute values of the outputs of the first and second subtracters during previewing is equal to or greater than a predetermined value.
