Inter frame

About: Inter frame is a research topic. Over the lifetime, 4154 publications have been published within this topic receiving 63549 citations.

Watermarking method and apparatus for compressed digital video

Abstract: A digital watermarking method and apparatus allows for the watermarking of a digital video signal in a compressed form, thereby allowing watermarking of a pre-compressed video sequence without requiring the decoding and re-coding of the signal. The watermark signal is a sequence of information bits which has been modulated by a pseudo-random noise sequence to spread it in the frequency domain. The video signal is transform coded, preferably with a discrete cosine transform, and a watermark signal, which has been transform coded using the same type of transform, is added to the coded video signal. The system also includes bitstream control to prevent an increase in the bit rate of the video signal. This allows the system to be used with transmission channels having strict bit rate constraints. For each transform coefficient of the video signal, the number of bits necessary to encode the watermarked coefficient is compared to the number of bits necessary to encode the unwatermarked coefficient. If more bits are required to transmit a watermarked coefficient than to transmit the corresponding unwatermarked coefficient, the watermarked coefficient is not output, and the unwatermarked coefficient is output in its place. When watermarking interframe coded data, a drift compensation signal may be used to compensate for the accumulating variations in the decoded video signal stored at the receiver. The system may also include an encryption/decryption capability, with the watermarking apparatus located at either the transmitting or receiving end of the transmission channel.

Encoding/decoding moving images with forward and backward keyframes for forward and reverse display

Abstract: A method of removing frame redundancy in a computer system for a sequence of moving images. The method comprises detecting a first scene change in the sequence of moving images and generating a first keyframe containing complete scene information for a first image. The first keyframe is known, in a preferred embodiment, as a "forward-facing" keyframe or intra frame, and it is normally present in CCITT compressed video data. The process then comprises generating at least one intermediate compressed frame, the at least one intermediate compressed frame containing difference information from the first image for at least one image following the first image in time in the sequence of moving images. In a preferred embodiment, this at least one frame is known as an inter frame. Finally, detecting a second scene change in the sequence of moving images and generating a second keyframe containing complete scene information for an image displayed at the time just prior to the second scene change. This is known, in the preferred embodiment, as a "backward-facing" keyframe. The first keyframe and the at least one intermediate compressed frame are linked for forward play, and the second keyframe and the intermediate compressed frames are linked in reverse for reverse play. In a preferred embodiment, the intra frame is used for generation of complete scene information when the images are played in the forward direction. When this sequence is played in reverse, the backward-facing keyframe is used for the generation of complete scene information.

A combined intraframe and interframe transform coding method

Abstract: An apparatus and method for signal processing employing intraframe and interframe variable prediction transform coding. Images are represented by sequential frames of two-dimensional arrays of digital signals. The digital signals are transformed to form transform coefficients for each frame. Predicted transform coefficients are formed using sets of variable prediction factors. The predicted transform coefficients for each frame are compared with corresponding actual transform coefficients for the frame to form transform coefficient difference signals. The difference signals are processed to control their range of values. The processed difference signals are statistically coded such that the more frequently occurring values are represented by shorter code lengths and the less frequently occurring values are represented by longer code lengths. The coded signals are stored in a buffer memory for transmission.

A unified approach to shot change detection and camera motion characterization

Abstract: This paper describes an original approach to partitioning of a video document into shots. Instead of an interframe similarity measure which is directly intensity based, we exploit image motion information, which is generally more intrinsic to the video structure itself. The proposed scheme aims at detecting all types of transitions between shots using a single technique and the same parameter set, rather than a set of dedicated methods. The proposed shot change detection method is related to the computation, at each time instant, of the dominant image motion represented by a two-dimensional affine model. More precisely, we analyze the temporal evolution of the size of the support associated to the estimated dominant motion. Besides, the computation of the global motion model supplies by-products, such as qualitative camera motion description, which we describe in this paper, and other possible extensions, such as mosaicing and mobile zone detection. Results on videos of various content types are reported and validate the proposed approach.

Motion dependent video signal processing

Abstract: In, for example, a motion compensated video standards converter (Figure 1) blocks in a first field or frame of a video signal are each compared (3) with a plurality of blocks in the following field or frame of the video signal for deriving motion vectors representing the motion of the content of respective blocks between the first field or frame and the following field or frame, a correlation surface is generated (3) for respective blocks in the first field or frame, the correlation surface representing the difference between the content of the block in the first field or frame and the content of each block in the following field or frame with which it has been compared, the correlation surface is tested (21, 22, 23) for a clear minimum, the size of the blocks is increased (20) to generate new correlation surfaces, each new correlation surface is tested (21, 22, 23) for a clear minimum, and motion vectors are derived (27) in dependence on the clearest minimum so found