JPH05300440A - Solid-state image pickup device - Google Patents

Abstract

PURPOSE:To remove band-shaped lateral stripes to appear on a screen and to vertically flow at the time of picking up the picture of a system provided with asynchronous and different vertical synchronizing frequencies. CONSTITUTION:The image data of a first frame outputted from a solid-state imaging device 1 are stored in a frame memory 3, and the image data of a second frame are stored in a frame memory 4. A comparator 5 compares the data of the first field of the first frame with the data of the first field of the second frame for each picture element, and the larger data are selected and outputted. Next, the image data of the second field of the first frame are compared with the image data of the second field of the second frame, and the data having a larger value are outputted. In the process of this comparison, the contents of the frame memory 3 are reloaded with the data of a third frame. In the next process of comparing the data of the second frame with the data of the third frame, the contents of the frame memory 4 are reloaded with the data of a fourth frame.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state image pickup device,
In particular, the present invention relates to a solid-state imaging device having improved image quality when images of an asynchronous system having different vertical synchronization frequencies are taken.

[0002]

2. Description of the Related Art Recently, with the spread of image media,
Conventional television format NTSC system, PA
Systems using a vertical synchronization frequency other than the L system and non-interlaced systems are being commercialized. For example, in the case of the NTSC system, the vertical synchronizing frequency is 60 Hz, so the vertical drive of the solid-state image sensor is also 60 Hz.
However, the vertical synchronizing frequency used in the display of a personal computer (hereinafter, referred to as a personal computer) is various, 56.4 Hz, 55.4 Hz.
Hz, 46 Hz, etc. are adopted.

Now, a state in which an image of a display screen of a personal computer is picked up by an NTSC video camera will be described with reference to FIG. 6A shows a signal indicating the vertical driving period of the video camera, and FIG. 6B shows a display signal of the personal computer with a positive polarity.

As described above, since the vertical synchronizing frequency of the NTSC system is 60 Hz, the signal charge reading is also 1 /
60 seconds (1 field period t ₁ in FIG. 6A)
It is done every time. On the other hand, since the vertical synchronizing frequency of the personal computer is lower than 60 Hz, the period t ₂ for one screen of the personal computer is longer than the one field period t ₁ . for that reason,
In each field of ,, and, the display screen of the personal computer displayed on the video monitor displays a black band-shaped horizontal stripe BL in the portion corresponding to the signal component not captured, that is, the period of Δt (t ₂ −t ₁ ). It appears, and because it is asynchronous, it flows vertically.

[0005]

As described above, when a conventional image pickup apparatus picks up an image of a system which is asynchronous and has a different vertical synchronizing frequency, the image displayed on the video monitor corresponds to a beat component. Strip-shaped horizontal stripes are generated, which flow in the vertical direction, which makes the screen extremely unsightly.

[0006]

A solid-state image pickup device of the present invention includes a solid-state image pickup element, a first or second and a third memory for storing an output signal of the solid-state image pickup element, and a first or second. The output signal of the memory is input as a first input signal, and the solid-state imaging device or the third memory in a field different from the first input signal and having the same spatial position as the first input signal. Of the first input signal or the second input signal, whichever is larger, is output as the second input signal.

[0007]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram showing a first embodiment of the present invention. As shown in the figure, the solid-state imaging device 1
The output signal of is converted into a digital signal by the A / D comparator 2 and then stored in the frame memory 3 or the frame memory 4. The comparator 5 compares the data in the frame memories 3 and 4 for each pixel and outputs the larger value as an output signal. This signal is converted into an analog signal by the D / A converter 6. The CPU 7 controls these series of operations.

Next, the operation of the first embodiment will be described. The image of the first frame output by the solid-state image sensor is stored in the frame memory 3, and the image of the second frame is stored in the frame memory 4. As shown in FIG. 2, black horizontal stripes appear in the image of each field, but the position of the horizontal stripe on the screen is different for each field.

The data of each pixel of the first field image of the first frame stored in the frame memory 3 and the data of each pixel of the first field image of the second frame stored in the frame memory 4 are compared. In step 5, the successive comparison is performed and the larger pixel signal is output. Now, the pixel Aik and the second pixel on the first frame side shown in FIG.
The pixel Bik on the frame side is compared with the pixel Bik
Is present in the black horizontal stripe BL, the signal level of the pixel Aik is higher than that of the pixel Bik.
The data of the pixel Aik is output from the comparator.

When the pixel Amn on the first frame side is present on the horizontal stripe BL, this signal level is lower than the signal level of the pixel Bmn of the second frame corresponding to this spatial position, so the comparator 5 determines Bmn data is selected and output.

When neither the pixel on the first frame side nor the pixel on the second frame side exists on the black horizontal stripe BL, the data of any one of the pixels is selected and output. Normally, the imaged screen is continuous on the time axis and has a strong correlation with the next screen. Therefore, even if the data of any screen is selected for pixels that do not exist on the horizontal line, there is almost no difference. Then, the pixels existing on the horizontal lines can be complemented by using the data of the next screen (or the previous screen) to obtain a complete image.

When the work of creating new data for the first field is completed, the same work is performed for the image of the second field of the first frame and the image of the second field of the second frame. The data in the working frame memory 3 is rewritten to the data in the third frame. That is, when the data of the first frame is output from the frame memory 3, the area in which the data is stored is sequentially replaced with the data of the third frame, and at the end of the above work, the content of the frame memory 3 is changed to the third frame. Has been replaced with the data of.

Next, work for creating new data is performed for the first field image of the second frame and the first field image of the third frame, and subsequently, the second field image of the second frame and the second field image of the third frame. The same work is done for. In parallel with the above work, the data in the frame memory 4 is rewritten to the image data of the fourth frame. Hereinafter, the same work is repeated in sequence.

FIG. 4 is a block diagram showing a second embodiment of the present invention. The output signal of the solid-state image sensor 1 is input to the field memory 8 via the A / D converter 2 and also becomes one input signal of the comparator 5. The data in the field memory 8 is output using the pulse generated by the pulse generator 9, and the output signal is the 1H delay circuit 1
The signal output via 0 is added by the adder 11 and attenuated to 1/2 by the 1/2 amplifier, and then input to the comparator 5.

Next, the operation of this embodiment will be described.
Now, it is assumed that the solid-state imaging device 1 is outputting the image data of the first field of the first frame. At this time, the field memory 8 stores the image data of the second field of the previous frame.
This data is sequentially output from the.

As shown in FIG. 5, when the solid-state image pickup device 1 outputs the data of the nth line of the first field, the field memory 8 outputs the data of the (n + 1) th line. The average value of the data of the line is input to the comparator 5. The average value and the data on the n-th line output from the solid-state image sensor 1 are compared for each pixel in the comparator 5, and the data with the higher signal level is output.

In the process of comparing the image data of the first field of the first frame with the image data of the second field of the previous frame, the data of the field memory 8 is replaced with the data of the first field of the first frame. Be done. Next, the solid-state image sensor 1 outputs the image data of the second field of the first frame, and this data is compared with the data of the first field stored in the field memory 8 in the comparator 5.

In this embodiment, since the comparison is made with the immediately preceding field image, the response is faster and the screen can be responded more quickly than in the case of the previous embodiment. Further, since only one field memory is required and its capacity is half that of the frame memory, the circuit scale is reduced and the configuration is simplified as compared with the case of the previous embodiment.

[0019]

As described above, according to the present invention, the output signal of the solid-state image pickup device is compared with the image data of other fields and the signal having the higher signal level is output as the correction data. According to the present invention, by adding a relatively simple circuit, a black horizontal line corresponding to a beat does not appear even when an image of a system having a different vertical frequency and being out of synchronization is captured, and a complete image is obtained. Can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a field state screen diagram for explaining the operation of the first embodiment of the present invention.

FIG. 3 is a field state screen diagram for explaining the operation of the first embodiment of the present invention.

FIG. 4 is a block diagram showing a second embodiment of the present invention.

FIG. 5 is a screen state diagram for explaining the operation of the second embodiment of the present invention.

FIG. 6 is a timing diagram of a conventional example and a screen state diagram thereof.

[Explanation of symbols]

 1 solid-state image sensor 2 A / D converter 3, 4 frame memory 5 comparator 6 D / A converter 7 CPU 8 field memory 9 pulse generator 10 1H delay circuit 11 adder 12 1/2 amplifier

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeru Kimura 1-403, Kosugi-cho, Nakahara-ku, Kawasaki-shi, Kanagawa 53-53 NEC IC Microcomputer System Co., Ltd.

Claims (1)

[Claims] 1. A solid-state image sensor (1), first or second and third memories (8; 3, 4) for storing output signals of the solid-state image sensor, and the first or second memory. The output signal of (8; 3) is input as a first input signal, and the solid-state imaging device (1) whose spatial position matches that of the first input signal in a field different from that of the first input signal. ) Or the output signal of the third memory (4) is input as a second input signal, and a comparator (5) that outputs the larger signal of the first and second input signals is provided. Solid-state imaging device.