What is motion compensation and motion estimation?

What is motion compensation and motion estimation?

Motion estimation examines the movement of objects in an image sequence to try to obtain vectors representing the estimated motion. Motion compensation uses the knowledge of object motion so obtained to achieve data compression. Such motion is difficult to estimate and may require large amounts of processing.

How do you estimate motion with temporal motion mode?

Bilinear interpolation was used to obtain intensity values at subpel locations of the reference frame. To mask the effect of the temporal propagation of prediction errors, motion was estimated and compensated using original reference frames.

What are the main steps of video compression based on motion compensation MC?

The three main steps of these algorithms are:

• Motion estimation (motion vector search)
• Motion compensation – based prediction.
• Derivation of the prediction error – the difference.

What is motion estimation how it is useful for video compression?

The motion estimation block in a video codec computes the displacement between the current frame and a stored past frame that is used as the reference. Usually the immediate past frame is considered to be the reference.

What is block compensation?

Block motion compensation divides up the current frame into non-overlapping blocks, and the motion compensation vector tells where those blocks come from (a common misconception is that the previous frame is divided up into non-overlapping blocks, and the motion compensation vectors tell where those blocks move to).

Why is motion estimation used?

Definition:Motion estimation explores the temporal redundancy, which is inherent in video sequences, and it represents a basis for lossy video compression. Other than video compression, motion estimation can also be used as the basis for powerful video analysis and video processing.

How does motion compensation work?

Motion compensation is an algorithmic technique used to predict a frame in a video, given the previous and/or future frames by accounting for motion of the camera and/or objects in the video. It is employed in the encoding of video data for video compression, for example in the generation of MPEG-2 files.

How do you estimate motion?

Motion estimation is the process of determining motion vectors that describe the transformation from one 2D image to another; usually from adjacent frames in a video sequence. It is an ill-posed problem as the motion is in three dimensions but the images are a projection of the 3D scene onto a 2D plane.

What is motion compensation VR?

Motion compensation is a feature that helps smooth frame rates in VR applications for a more seamless visual experience.

What are the three types of frame used in motion estimation of MPEG compression algorithm for video?

Three types of pictures (or frames) are used in video compression: I, P, and B frames. An I‑frame (Intra-coded picture) is a complete image, like a JPG or BMP image file. A P‑frame (Predicted picture) holds only the changes in the image from the previous frame.

What is meant by motion compensation?

How is motion estimation done in Hevc?

This is done by multiplying the distance by two in each iteration. Hence, at a distance equal to one, the search for two adjacent points is applied in order to choose the best estimated motion vector having the best Sum of Absolute Difference (SAD).

What is block motion compensation (BMC)?

In block motion compensation (BMC), the frames are partitioned in blocks of pixels (e.g. macroblocks of 16×16 pixels in MPEG). Each block is predicted from a block of equal size in the reference frame.

What does MPEG block motion compensation look like?

Visualization of MPEG block motion compensation. Blocks that moved from one frame to the next are shown as white arrows, making the motions of the different platforms and the character clearly visible.

Do we need local motion estimation for motion compensation?

Thus, local motion estimation is also needed. Block motion compensation (BMC), also known as motion-compensated discrete cosine transform (MC DCT), is the most widely used motion compensation technique. In BMC, the frames are partitioned in blocks of pixels (e.g. macro-blocks of 16×16 pixels in MPEG ).

What are the advantages of motion compensation in video compression?

When images can be accurately synthesized from previously transmitted/stored images, the compression efficiency can be improved. Motion compensation is one of the two key video compression techniques used in video coding standards, along with the discrete cosine transform (DCT).