Abstract: A method of reducing ringing artifacts in image data that has been filtered with a high frequency emphasis filter. For each filtered data value, a local variance is calculated from data values at neighboring filter taps. This variance is compared to a threshold, and if the threshold is exceeded, the filtered data value is limited between local minimum and maximum values. A method of reducing noise, also using the local variance, is also described.

Abstract: A digital keystone correction process locates image points in a corrected image from image points in a distorted image that was produced by misalignment of the axis of a sensor such as a camera. The correction process locates corrected image points by constructing intercept points that are the intersections of the extended sides of a quadrilateral in the distorted image plane that is constructed from a known rectangular feature in the subject plane. Reference points are located by drawing a line through each intercept point and the distorted image point. Distances are found from the intercept points to the image points and the reference points. The distances are scaled and corrected with an offset to locate the coordinates of the image points in the corrected image plane. This process can correct alignment errors of pitch, yaw, and roll between the subject plane and an image plane such as photographic film.

Abstract: A digital circuit, system, and method for keystone correction of a projected image utilize a digital keystone correction engine to resize a raster-scanned input image prior to projection. An image keystone correction engine uses coordinates of the corners of the image on the display device that are modified to produce a resized image for projection onto a screen. Scaling factors are generated at the corners of the image to represent image scaling along two image axes that span the area of the image to form a resized image on the display device by repositioning pixels from an uncorrected or previously resized image. The variation of the scaling factors across the image can be assumed to be linear.

Abstract: In accordance with the teachings of the present invention, a system and method for local saturation adjustment are provided. In one embodiment, the method includes identifying a hue, saturation, and brightness value of each pixel of an image, determining whether the hue and saturation of each pixel fall within a predetermined set of hue and saturation combinations, determining whether the brightness value of each pixel falls within a predetermined set of brightness values, and selectively applying a gain to the saturation of each pixel based upon the determination of whether the hue and saturation of the pixel fall within the predetermined set of hue and saturation combinations, and whether the brightness value of pixel falls within the predetermined set of brightness values.

Abstract: In accordance with the teachings of the present invention, a system and method for local value adjustment are provided. In one embodiment, the method includes identifying a hue, saturation, and brightness value for each pixel of an image, determining whether the hue and saturation for each pixel fall within a first predetermined set of hue and saturation combinations, determining whether the brightness value for each pixel of the image falls within a predetermined set of brightness values, and selectively applying a gain to the saturation of each pixel based upon the determination of whether the hue and saturation value of the pixel falls within the first predetermined set of hue and saturation combinations and the determination of whether the brightness value of the pixel falls within the predetermined set of brightness values.

Abstract: Methods for improving video images by making real-time gamma correction adjustments to such images are described. More particularly, gamma correction adjustments may be optimized for each individual frame of a video image by first segregating the pixels of an image according to brightness. The segregated pixels may then be used in computing weighting calculations, which modify the transfer functions used for image display. In some embodiments, the video signal may be conditioned between the standard gamma curve and the S-shaped gamma curve used in mapping video signal input to intensity output. In this manner, frame-to-frame gamma correction adjustments can be made, thereby optimizing the resulting image. Related systems for making frame-to-frame gamma correction adjustments are also described.

Abstract: A control module for use in an image display system includes a histogram module operable to collect data associated with a first frame of a signal received by the control module. The histogram module comprising a plurality of storage modules capable of counting a plurality of pixels associated with the first frame. In one particular embodiment, each of the plurality of pixels comprises a maximum intensity component at a particular color level. The control module further includes a processor capable of determining a new position of an adjustable aperture based at least in part on the data collected by the histogram module. The processor further capable of determining a gain to apply to a subsequent frame of the signal based at least in part on the new adjustable aperture position.

Abstract: An adjustable aperture system includes a stationary aperture operable to remove a portion of a lower intensity light communicated through a light bundle. The system also includes an adjustable aperture comprising a notch and capable of varying an amount of projection light communicated through the light bundle. In one particular embodiment, the notch operates to reduce the effect of the adjustable aperture on a high intensity light communicated through the light bundle. The system further includes a control motor operable to receive a control signal and to selectively manipulate the adjustable aperture.

Abstract: A control module for use in an image display system includes a gain module operable to amplify a signal received by the control module and to communicate an amplified signal having at least one clipped pixel. The at least one clipped pixel is capable of generating a color having a hue that is substantially different than a hue of a color that was intended to be generated by the signal. The control module further includes a formatter coupled to the gain module. The formatter operable to receive the amplified signal and to adjust the hue of the color associated with the at least one clipped pixel. In one particular embodiment, the hue of the color associated with the at least one clipped pixel is adjusted to substantially the hue of the color that was intended to be generated by the signal.