Digital Imaging Systems Gmbh

Youliza, Gehts B.v. Limited Liability Company

Dialog Semiconductor Gmbh

Oigital Imaging Systems Gmbh

Detlef Schweng

Horst Knoedgen

Taner Dosluoglu

Stefan Spaeth

Hubert Utz

A digital color imager providing an extended luminance range, an improved color implementation and enabling a method for an easy transformation into another color space having luminance as a component has been achieved. Key of the invention is the addition of white pixels to red, green and blue pixels. These white pixels have either an extended dynamic range as described by (U.S. Pat. No. 6,441,852 to Levine et al.) or have a larger size than the red, green, or blue pixels used. The output of said white pixels can be directly used for the luminance values Y of the destination color space. Therefore only the color values and have to be calculated from the RGB values, leading to an easier and faster calculation. As an example chosen by the inventor the conversion to YCbCr color space has been shown in detail.

Sensor arrangement for transforming color space representation in a digital color image

Methods to zoom a region of interest from a digital image have been achieved. The methods invented support according to the scale of zooming the decrease or the increase of the resolution of digital images. The region of interest to be zoomed is variable; the destination image has a fixed size. In case of a decrease of the resolution of the region of interest the method invented combines interpolating source pixels to calculate the color values of the destination pixels and omitting some rows of source pixels. In case of enlargement the method invented combines interpolation of the source pixels to calculate the color values of the destination pixels, extrapolation of the destination pixels being close to the edge of the image, and replication of some of the interpolated rows of the destination image to gain additional rows according to the scale of the increase of resolution (enlargement) of a digital image.

Zoom algorithm

A digital color imager providing an extended luminance range, an improved color implementation and enabling a method for an easy transformation into another color space having luminance as a component has been achieved. Key of the invention is the addition of white pixels to red, green and blue pixels. These white pixels have either an extended dynamic rang as described by U.S. patent (U.S. Pat. No. 6,441,852 to Levine et al.) or have a larger size than the red, green, or blue pixels used. The output of said white pixels can be directly used for the luminance values Y of the destination color space. Therefore only the color values and have to be calculated from the RGB values, leading to an easier and faster calculation. As an example chosen by the inventor the conversion to YCbCr color space has been shown in detail.

Extended dynamic range in color imagers

Systems and related methods have been achieved to convert in an analog domain the output of color image sensors into another color space. A chosen implementation converts the output of red, green, blue and white image sensors to the YcrCb color space, wherein the white image sensors are either extended dynamic range (XDR) image sensors or are of the same type as the other image sensors but have a larger size. The output of the white pixels can be used without conversion directly for the luminance Y value, thus achieving a very simple method for a conversion to YCbCr color space. Analog amplifiers, assigned to each of the red, green, and blue image sensors, have a gain according to the matrix describing the conversion from RGB to CbCr. Analog adders, assigned to Cb and Cr are adding the coefficients required for the computation of Cb and Cr. Finally the values of Y, Cb and Cr are converted to digital values. White pixels are advantageous but not required using the present invention. The present invention is also applicable for conversion to other color spaces as e.g. YIQ, YUV, CMYK, HIS, HSV, etc.

Color space conversion in the analog domain

Methods to convert the resolution of digital images have been achieved. The methods invented support the decrease or the increase of the resolution of digital images, even enlargement in one direction and decimation in the other direction. The methods invented are applicable for any color space used. In case of decimation the method invented combines an interpolation of source pixels to calculate the color values of the destination pixels and omitting some rows of source pixels. A linear interpolation method is used to get a fast result of the interpolation. In case of an enlargement of a digital image in one or two directions the method invented combines the calculation of the color values of the destination pixels by an interpolation of the nearest source pixels with an extrapolation of the destination pixels being close to the edge of the image according to the scale of the conversion of resolution in one or two directions.

Image resolution conversion

An apparatus, a circuit and a method are given, to realize very effective noise suppression for speech signals. Using thereby novel calculation methods allow for a real-time operation without any remarkable delay. Also a significant reduction of the overall processing power demands in conjunction with reduced memory requirements is achieved. Using the intrinsic advantages of that solution the circuit of the invention is manufactured with standard CMOS technology and/or standard Digital Signal Processors at low cost.

Delay free noise suppression

A method to convert line-based pixel data from an imager, e.g. a video camera into block-based pixel data with a minimum of buffer memory size has been achieved. Key of the invention is that as soon pixel data are read-out of a buffer memory, pixel data of the next image are written to the same position of the buffer memory as the pixels, which have been just read-out have been located. While in prior art the buffer memory required a capacity to store two images is, using the method invented, only a capacity to store one image required. A method to convert line-based pixel data for an image application reading-out column-wise has been illustrated in detail. This general method can be used for a multitude of image transformations and image compression methods e.g. for compression of pixel data as JPEG, for mirroring, tilting, rotating etc. of line-based pixel data.

Size optimized pixel line to pixel block conversion algorithm

A method used for the compensation of vignetting in digital cameras has been achieved. The compensation for vignetting is performed by multiplying pixel output of the sensor array with a correction factor. In a preferred embodiment of the invention all pixels are multiplied with an adequate correction factor. Alternatively pixels, being close to the center of the sensor array, can be left unchanged. Said correction factor can be calculated in a very fast and efficient way by using two constant factors describing the specific geometry of the lens/sensor array system and by multiplying a first of said factors with the square of the distance between a pixel and the center of the sensor array and by multiplying a second of said factors with the distance between a pixel and the center of the sensor array to the power of four. The result of the second multiplication is subtracted from the result of the first multiplication and this result is added to one to get the final correction factor. Each original pixel output is multiplied with said correction factor to get output data compensated for the vignetting effects of the lens.

Lens shading algorithm

A digital color imager providing an extended luminance range, enabling a method for an easy transformation into all other color spaces having luminance as a component. White pixels are added to hexagonal red, green and blue pixels. These white pixels can alternatively have an extended dynamic range as described by U.S. Pat. No. 6,441,852 (to Levine et al.). Especially the white pixels may have a larger size than the red, green, or blue pixels used. This larger size can be implemented by concatenation of 'normal' size hexagonal white pixels. The output of said white pixels can be directly used for the luminance values Y of the destination color space. Therefore only the color values have to be calculated from the RGB values, leading to an easier and faster calculation. As an example chosen by the inventor the conversion to YCbCr color space has been shown in detail.

Hexagonal color pixel structure with white pixels

A digital color imager provides an extended luminance range, enabling a method for an easy transformation into all other color spaces having luminance as a component. White pixels are added to hexagonal red, green and blue pixels. These white pixels can alternatively have an extended dynamic range as described by U.S. Pat. No. (6,441,852 to Levine et al.). Especially the white pixels may have a larger size than the red, green, or blue pixels used. This larger size can be implemented by concatenation of 'normal' size hexagonal white pixels. The output of said white pixels can be directly used for the luminance values Y of the destination color space. Therefore only the color values have to be calculated from the RGB values, leading to an easier and faster calculation. As an example chosen by the inventor the conversion to YCbCr color space has been shown in detail.

Growing community of inventors

Weinstadt-Schnait, Germany

Detlef Schweng