1. Field of the Invention
The invention relates to a method and device for chrominance signal interpolation. The invention also relates to a display apparatus comprising such a device.
2. Description Of The Related Art
It is known from literature (see Ref. [3] in the List Of References) that the Human Visual System (HVS) is more sensitive to luminance than to chrominance stimuli. Therefore, in many video-processing algorithms, the algorithm applied to the luminance signal is much more advanced then the one applied for the chrominance signal.
In scan-rate-conversion algorithms, like the PROZONIC (see Ref. [1]) and MELZONIC (see Ref. [2]), color processing is non-motion compensated. Motion artifacts in the chrominance signal caused by the conversion from, e.g., 50 Hz interlaced to 100 Hz interlaced are, to a significant extent, masked by the fact that the HVS is less sensitive to the chrominance signal as stated before. However, for very saturated colors, the artifacts can become visible and annoying.
If the luminance signal is motion compensated (MC) while the chrominance signal isn""t, a misalignment in moving objects occurs for temporal interpolated images. This misalignment is especially annoying for very saturated dark colors, where the constant luminance principle is jeopardized most severely due to the gamma correction of individual R, G, and B signals.
It is, inter alia, an object of the invention to provide an improved chrominance signal interpolation. To this end, the invention provides a chrominance signal interpolation method and device, and a display apparatus comprising such a device.
In a method of chrominance signal interpolation in accordance with a primary aspect of the present invention, in which output chrominance signals are interpolated from mutually corresponding input chrominance signals from mutually neighboring input images, a color saturation value of at least one of the output chrominance signals is smaller than an average of color saturation values of the mutually corresponding input chrominance signals corresponding to the one output chrominance signal if the mutually corresponding input chrominance signals meet a predetermined criterion. The expression corresponding means that the chrominance signals concerned correspond both as to spatial positions in the mutually neighboring input images and as to chrominance type, i.e., either U/I or V/Q. The criterion may be that the reference value lies between the corresponding input chrominance signals, or that differences between the corresponding input chrominance signals exceed a predetermined threshold.
These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.