Method and apparatus for fast block motion detection

Abstract

A method, system, and / or apparatus for quickly detecting blocks or regions in an image whose pixels that can be coded efficiently by a pointer to the same block occurring in a reference image. The reference image is shared between an encoder and a corresponding decoder. One embodiment of the encoder quickly detects such blocks in an image by: (a) defining features such that substantially fewer features occur in an image than pixels, (b) correlating features in an image to a corresponding feature in the reference image, (c) estimating a displacement vector representative of the displacement of the correlated features, (d) estimating a seed point within the displaced block from which to grow the block, and (e) growing the displaced block to determine its size, shape, and / or dimensions.

Description

FIELD [0001] One aspect of the invention generally relates to encoding contents of a display screen in real-time. More particularly, one embodiment of the invention provides an apparatus and / or method for detecting a block in an image that occurs verbatim in a reference image, the reference image is shared between an encoder and a decoder and, thus, the block can be coded efficiently by a pointer to its previous occurrence. BACKGROUND [0002] Many applications, such as remote access software and screen recording software, often encode the contents of a computer screen in real-time. These applications typically represent the contents of a screen as compactly as possible because of bandwidth or storage constraints. [0003] Software for encoding the contents of a computer screen (the encoder) is naturally complemented by software for decoding and displaying the encoded contents (the decoder) at a different location or later time. The encoder typically acquires the contents of a computer ...

AI Technical Summary

Benefits of technology

"The present innovation provides a method, system, and / or apparatus for quickly detecting blocks in an image that can be coded efficiently by a pointer to the same block occurring verbatim (or probabilistically or approximately) in one of a limited number of reference images. The method involves defining features that are representative of the characteristics of an image and mapping each feature in an image to a feature in one of the reference images such that it is likely that the corresponding pixels surrounding such a pair of features match. The method also involves iteratively estimating a pixel location that is contained in the largest block and its corresponding pixel location in one of the reference images based on these mappings before determining its size at the pixel level. The technical effect of this innovation is to enable efficient coding of image blocks by a pointer to the same block occurring in a reference image."

Problems solved by technology

However, implementing this method is often not feasible because it is not easily ported to other platforms, requires administrative privileges (e.g., display driver access is often restricted), requires a reboot (e.g., to install a new device driver), and / or lowers the stability of the overall system (e.g., most remote control packages interfere with one another).

On the other hand, representing screen contents by a sequence of images typically leads to very large representations.

Large representations usually hinder the overall system performance (i.e., cause perceivable delays).

While encoding blocks that occur verbatim in previous screens by a pointer is highly space-efficient, doing so in a timely manner is computationally demanding because, in the general case, it requires an exhaustive search.

A related problem is motion-compensated video signal coding where motion estimation is used to predict the current frame and to encode the difference between the current frame and its prediction.

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