DE19630009A1 - Receiver system for video telephone system - Google Patents

Abstract

The received image of a video telephone system is distorted due to an incorrectly positioned camera relative to the object. The image is subjected to a correction process that is based upon an expansion within a line to the left and right of a centre point using a progressive algorithm. The expansion is made until defined boundaries are reached.

Description

The invention relates to a subscriber device for telephony with a Image display device and one arranged close to this Image recording device, its beam paths on the participant are aligned.

Such a subscriber device is known (EP-A-0595049). At the recording the picture of a videophone subscriber with a deeply arranged Image recording device, for example at the level of a The desktop surface is arranged, the image appears to the viewer of the Image display device by the obliquely upward-facing camera recorded in perspective. Such a distortion is also called Frog's perspective. This effect shows an unfavorable picture of the videotaped subscriber because such a picture of which the Of the videophone subscriber viewing the picture as unusual ("from below looking ") is felt used wide angle lens, which is used to get a capture larger image section.  

The technical problem underlying the invention therefore exists in creating a subscriber device for telephony in which the image displayed by the image display device is not a perspective Distortion. This technical problem is in accordance with the invention solved in that a recorded by the image recording device perspective image is electronically corrected.

The image captured by the image pickup device becomes for example in preparation for transmission, such as by coding or the like, electronically in the transmitting part of the video telephone device equalized. This is one - on the lens of the image recording device related - spherically arranged reality depicted in one plane and the existing perspective distortion by one simple algorithm corrected as well as possible.

This correction is carried out according to the method specified in claim 2 performed.

The invention is explained below with reference to FIGS. 1 and 2. Show it:

Fig. 1 shows the perspective image of an image recording device and

Fig. 2 shows the image of FIG. 1 after the electronic correction.

Fig. 1 shows the original rectangular image which appears in perspective recorded by the unfavorable positioned image pickup device: The width of the image decreases from bottom to top, the upper part of the image appears to the viewer tilted away.

Fig. 2 shows the reproduced by the image reproducing device electronically corrected image. The electronic equalization takes place in different ways in the upper and lower part of the picture:

• 1. Electronic correction in the upper part of the picture, ie above the transverse axis Q:
  Within a line, the image is stretched to the left and right starting from the vertical axis H by adding further pixels distributed over the entire length. The closer the line is to the top of the screen, the more stretch points are inserted across the line. In addition, stretch lines are inserted according to the situation. Part of the optimal adaptation to the lens is to set the expansion points depending on the distance to the central axis. The required expansion points are generated in brightness and color in accordance with the average of the neighboring pixels.
  In this way, the impression of distortion caused by removal can be significantly reduced or even completely eliminated.
• 2. Electronic correction in the lower part of the picture, ie below the transverse axis Q:
  Within a line, the image is reduced from the vertical axis H to the left and right by removing certain pixels along the entire width. The closer the line is to the bottom of the screen, the more pixels are removed from the line. In addition, entire lines are removed according to the situation. Part of the optimal adaptation to the lens is to do this deletion of pixels depending on the distance to the central axis. In this way, the impression of distortion due to proximity can be significantly reduced or even completely eliminated.

Inserting expansion lines and expansion points creates the image impression, that in perspective the distant is getting closer; or the complete removal of Image lines and pixels create the reverse impression that close appears further away.

Claims (2)

1. Subscriber device for telephony with an image display device and an image recording device arranged close to it, the beam paths of which are aligned with the subscriber, characterized in that a perspective recorded image recorded by the image recording device is electronically corrected. 2. A method for the electronic equalization of a perspective recorded image, characterized in that

• a) the upper part of the image depending on the height and width, starting from its transverse axis and the vertical central axis, in height and width is stretched according to a progressively oriented algorithm and
• b) the lower part of the image depending on the height and width, starting from its transverse axis and the vertical central axis, is reduced in height and width according to a progressively oriented algorithm.