JPS58205386A - Binary-coding device of video signal - Google Patents

Abstract

PURPOSE:To obtain accurate binary-coded video signals at all times, by providing a memory storing at least one field of one of the 1st and the 2nd video signal and a comparison means comparing the video signal from this memory with the other video signal. CONSTITUTION:Before a Telop material is picked up, a solid black board is picked up and converted into PCM signals at an A/D converter 3 and stored in a frame memory 5 via a switching device 4. Then, a board described with a title is picked up and its video signal is inputted to a comparator 7 via the A/D converter 3 and the switching device 4. Simultaneously, the video signal from the memory 5 is inputted to the comparator 7, from which a binary-coded video signal is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a video signal binarization device that generates a binarized signal from a digital television video signal that has shading due to camera lenses, uneven lighting, and the like.

Generally, a binary video signal is created from a subtitle or the like taken by a camera, but the video signal from the camera is subject to shading due to various factors such as the camera lens and uneven lighting. Conventionally, this video signal was binarized by simply comparing it with a certain slice level. For this reason, depending on the position on the screen, an image signal at the very edge of the slice level may appear, making it impossible to obtain an accurate binarized video signal. Therefore, if the camera or lighting changed, it was necessary to set the optimal slice level again. This setting also depends on human hands, and it takes time and effort to adjust it to the optimum value.

Therefore, it is an object of the present invention to perform video signal binarization that eliminates the need for frequent adjustment of slice levels and always provides accurate binarized video signals even if the video signal from a television camera includes shading or the like. The purpose is to provide equipment.

According to the present invention, there is provided a digital memory that stores one field or one frame of a reference digital television video signal, a control unit that controls reading and writing thereof, and an input television video signal and an already stored reference digital television. A video signal binarization device is obtained, which includes a comparison circuit that compares the video signal with the John Eirin signal and generates a binarized video signal.

The invention will now be described in detail with reference to figures of one embodiment of the invention. First, a conventional system will be briefly described using FIG. 1 to help understand the present invention. FIG. 1 shows a block diagram of a conventional binarization device, which consists of a comparator 1 and a slice level setting section 2. The input video signal is compared with the slice level VTE by a comparator IK,
The two-chain body designation is obtained from that output. However, when a subtitle material is photographed with a camera, for example, the lens has optical characteristics as shown in FIG. 2, so the difference from the slice level will vary in each part. Moreover, illumination irregularities and the like are usually added, and a signal at the very edge of the slice level is generated, making it impossible to obtain an accurate and stable binary video signal.

FIG. 3 is a diagram showing an embodiment of the present invention. In this embodiment, in order to simplify the explanation, shading of only the camera lens will be considered. In the figure, before photographing the subtitle material, a plain black board is photographed, converted into a PCM signal by an A/D converter 3, and then stored in a frame memory 5 via a switch 4. The operation of the switch 4 and the control of the memory 5 are performed by a control circuit 6. Needless to say, this stored video signal is subjected to shading by a camera lens.

Next, write the title on the front board, take the same photo, and use the A/D
Supplied to converter 3. The video signal converted to the PCM signal is then input to one input terminal of the comparator 7 by the switch 4 and the control circuit 6. At this time, the stored PCM signal is supplied from the memory 5 to the other input terminal of the comparator 7 via the switch 8, and the two video signals are compared. If the compared values exceed a certain level difference, an output is output from the comparator and a binary video signal is obtained.

In the present invention, shading can be canceled out by sequentially comparing the difference between a video signal of a plain black material that includes shading stored in the frame memory and a video signal of a title that also includes shading. Therefore, only the portion where the title is written has a level difference, and a binarized signal that is not affected by shading is obtained as the output of the comparator.

Figure 4 is a diagram explaining the present invention in detail, (a) shows an example of the characteristics of a camera lens when a plain black material is used, and (b) shows the title model and the results obtained from it. This shows the basic video signal.

(C) shows the video signal obtained from the camera when the title was shot with this camera. (d) is obtained according to the invention, ie from the comparator 7 of FIG.

A binary video signal is shown.

It goes without saying that shading due to lighting is likewise eliminated by the present invention. By the way, a bias light is generally used to solve the problem of afterimages in image pickup tubes. Although some of the shading caused by this is corrected by the camera, shading characteristics that are 8-shaped or partially protruding are not corrected. However, the present invention is also effective for such shading removal.

The above description refers to black shading, but the same applies to white shading, which has been particularly problematic. That is, a white subject is taken and its video signal is stored in the memory 5. It is obvious that if a video signal with a title written below is inputted, a binarized signal from which shading has been removed can be obtained by the comparator 7. Needless to say, since the polarity of the output binary signal is inverted, a polarity inversion circuit may be provided on the output side or the like.

[Brief explanation of the drawing]

Figure 1 is a block diagram of the conventional system, Figure 2 is a model diagram of camera shading, Figure 3 is a block diagram of an embodiment of the present invention, and Figure 4 is a book using camera lens shading as an example. Detailed explanatory diagram of the invention In the figure, 1... comparator, 2... slice level setting section, 3... A/D converter, 4
...Signal switch, 5...Frame memory, 6...Control unit, 7...Comparator, 8
······switch.

Claims (1)

[Claims] The device receives the reference first video signal and the second video signal to be binarized and generates the binarized video signal by comparing the first and second video signals, - a binary video signal, comprising: a memory for storing at least one field of one of the first and second video signals; and comparison means for comparing the video signal from the memory and the other video signal. conversion device.