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STILL IMAGE MODE TRANSMISSION USING SUM OF ABSOLUTE DIFFERENCES

IP.com Disclosure Number: IPCOM000009411D
Original Publication Date: 1999-Sep-01
Included in the Prior Art Database: 2002-Aug-21
Document File: 3 page(s) / 159K

Publishing Venue

Motorola

Related People

Paola M. Hobson: AUTHOR [+3]

Abstract

The idea relates to still image video transmis- sion. A Sum of Absolute Difference (SAD) calcula- tion is used to determine the time at which a dis- played image has reached a sufficient quality such that no further progressive refinement bits need be transmitted. This both optimizes the quality in an automated way for the viewer, and reduces the bandwidth demands on the transmission system.

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Developments Technical 0 M MOTOROLA

  STILL IMAGE MODE TRANSMISSION USING SUM OF ABSOLUTE DIFFERENCES

by Paola M. Hobson, Anthony R. May and Arthur Lallet

frame' command in me encoder, which modifies its operation. The user can be located either at the camera- or display end.

  After generation of the 'freeze frame' command, the progressive refinement start tag is inserted in the bitstream. This tag indicates that the current picture is followed by a sequence of several pictures of refinement of the quality of the current picture. This sequence is stopped by receipt of the progressive refinement segment end tag or when timeout occurs. See Figure 1.

  After several enhancement frames, also termed 'E frames', the displayed picture quality in practice no longer shows any discernable visual improve- ment. Further transmission of enhancement frames after this is a waste of bandwidth.

  Our enhancement to this procedure relates to the method used to determine when to stop sending the enhancements. Clearly, it is important for band- width saving reasons to send as few enhancement frames as possible.

  Our enhancement technique uses the first differ- ence of the Sum of Absolute Difference (SAD) between the reconstructed frame and the original frame at the H.263 encoder to determine the number of E frames necessary to get a good quality picture at the receiver.

  The minimum number of E frames necessary to get a good quality picture at the receiver is deter- mined by the following algorithm:

  1. Calculate the value Cn of the SAD between the nth reconstructed frame and the original frame;

  2. Normalize this value of Cn to the first SAD calculated,

0 Mommla, 1°C. 1999 13 September 1999

ABSTRACT

  The idea relates to still image video transmis- sion. A Sum of Absolute Difference (SAD) calcula- tion is used to determine the time at which a dis- played image has reached a sufficient quality such that no further progressive refinement bits need be transmitted. This both optimizes the quality in an automated way for the viewer, and reduces the bandwidth demands on the transmission system.

INTRODUCTION

  Within a video transmission system the user may have a need to transmit a still image from time to time. This might be a "freeze frame" in a video sequence, or a wish by the customer to use their video camera to send a single frame still image. This paper describes a still image transmission method using the H.263 compression standard [Il.

  The idea may or may not use the progressive refinement and freeze frame in annex L of the H.263 specification.

PROBLEM(S) TO BE SOLVED

  The H.263 method of video compression does not specify how to handle still images. We modify the operation of the video encoder to enable a still image mode to be implemented, whilst remaining compliant with the H.263 standard.

PROPOSED SOLUTION TO THE PROBLEM(S)

  Assume that a video transmission system is sending H.263 encoded video from a camera to a remote display. At some point during the video...