Improved methods and apparatus for digital focal plane array (FPA)--based color imaging include the step of sampling an image, using an FPA camera equipped with a color filter array (CFA) to obtain a value at each pixel position, thereby creating a set of values sampled on a per-pixel basis. Single-color cyan, yellow and white (CYW) color planes are generated from the set of sampled pixel values. Interpolates among and between the color plane values is executed to "fill in" the "gaps" in the individual color planes, and the interpolated CYW values from the single-color planes are transformed into RGB values which can be stored, transmitted, or utilized to drive a conventional video monitor or color printing device. Filtering and other post-interpolation steps are executed to reduce color aliasing, and the white plane is used to introduce high frequency content back into the filtered color image. In one practice of the invention, the CYW values are transformed into CIELAB color space values. The interpolated W plane is used to calculate L* values, and C, Y, and W planes are used to calculate a* and b* values. The a* and b* planes are filtered using a window with weighting coefficients, and the CIELAB color space values are then transformed to red, green, and blue color planes using a color look-up table (LUT). In this case, the luminance of each pixel is directly related to the W plane value at that pixel location.
A semiconductor imaging sensor utilizes a color filter pattern. The imaging sensor includes light sensitive-elements, each of which is sensitive to photon energy in a spectral region or color band associated with the light-sensitive elements. Select light-sensitive elements in the array are sensitive to energy in a wide band spectral region or "white" color band. This permits the capture of color information which can be lost with the use of typical semiconductor imaging sensors in digital photography. This capture of the additional color information in digital photography allows for better quality of reproduction of an image on a selected medium such as color prints.
This invention relates to the reconstruction of a full colour image from image mosaic data in particular where the image mosaic data is unequally weighted between different colours. The image mosaic is composed of a plurality of image pixels. Each image pixel has one of at least three colour values and has a luminance value representing the intensity of the colour value for that pixel in the image mosaic. The pixels of each colour value are interleaved across the image mosaic with pixels of different colour values to form the image mosaic. For each colour value, both a low spatial frequency monochrome image and a high spatial frequency luminance image are generated, the high spatial frequency luminance image extending only across pixels locations of the image mosaic for that colour value. Each of the high spatial frequency luminance images is then combined with a corresponding low spatial frequency monochrome image to form the full colour image.
A method of, and an apparatus for, image conversion. The three color channels of a Bayer mosaic image are up-interpolated from input space to output space. The pixels sampled from each two-dimensional color plane of the Bayer image are convolved with a coefficient kernel for each color. To facilitate reconstruction and resampling, the color space for a dominant pixel color of the Bayer image is effectively rotated. The generation of each color value for a given pixel coordinate is carried out in parallel using an identical convolve unit and a dedicated coefficient kernel for each color.
A complementary-color-filtered array interpolation by first interpolate each color subarray so each pixel has four colors and then adjust each color at a pixel with addition or subtraction of a color imbalance factor for the pixel. For yellow and cyan the adjustment is subtraction but for magenta and green the adjustment is addition.
A solid-state imaging apparatus includes an image pick-up section in which photosensitive devices are arranged in, e.g., a honeycomb G square lattice, RB full-checker pattern due to shifted pixels. Regions void of the photosensitive devices are assumed to be virtual photosensitive devices. A signal processing section generates data for the virtual photosensitive devices by using the data of surrounding photosensitive devices while attaching importance to accurate color reproduction and horizontal and/or vertical resolution. As a result, the number of pixel data are increased in a square lattice arrangement. Therefore, high quality image signals are readily achievable with a smaller number of photosensitive devices than conventional with a conventional apparatus. Interpolation can be executed with the high quality signals to the limit of resolution with an adequate circuit scale. The honeycomb arrangement guarantees the required size of the individual pixel and thereby the sensitivity of the entire apparatus while increasing yield on a production line. False colors particular to a single photosensitive portion can be reduced by, e.g., uniform interpolation. Particularly, when a digital camera is constructed by using an imaging apparatus including optics operable with a silver halide sensitive type of film, false colors can be reduced without resorting to an optical low pass filter.
