JPH02134083A - Digital picture signal processing unit - Google Patents

Abstract

PURPOSE:To reduce the effect of jitter and noise at reproduction by digitizing a still picture signal recorded on a floppy disk and averaging several fields (or frames). CONSTITUTION:A still picture recorded analogically on a floppy disk 201 is reproduced by a magnetic head 202 and a preamplifier 203 and demodulated by a demodulation circuit 204. Then an analog signal subject to signal processing in various kinds at a process circuit 203 is digitized by an A/D converter 206. Then in order to obtain one frame of original picture (digital original picture signal for digital signal processing), the signal is reproduced for plural number of times and the plural signals are added, then the effect due to uneven rotation is averaged and the effect is improved according to number of times of addition. Thus, the effect of jitter or noise at reproduction is reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention reproduces a still image signal recorded on a magnetic disk such as a floppy disk, performs A/D conversion, and then subjects the digital still image signal to digital data processing. The present invention relates to an image signal processing device.

[Conventional technology]

The present invention can be applied, for example, to an image signal processing device of a transmitting device of a so-called electric transmission system that transmits a still image converted into an analog signal onto a floppy disk to a remote receiving device via a telephone line.

When transmitting a still image using an electric transmission system, various conditions of the image to be transmitted, such as whether the brightness distribution is wide or narrow, whether the entire image is biased towards brightness or darkness, etc. It is necessary to perform image signal processing such as gamma correction on the transmitting side depending on various circumstances such as whether the image is bright or dark and the sensitivity characteristics of the receiving device. Gamma correction in conventional electric transmission systems involves A/D converting an image signal on the transmitting side, and image processing (eg, digital gamma correction) on the digitally converted image signal using digital signal processing technology. Conventionally, when carrying out the A/D conversion, a reproduced analog signal is used to reproduce one field when one frame is recorded in one field, and one field for two fields when one frame is recorded in two fields. It was doing A/D conversion. In this A/D conversion method, the analog image signal that is the basis for A/D conversion contains jitter due to rotational unevenness of the disk drive device. The effect of jitter causes almost no visual problem in the case of a moving image, but in the case of a still image, if a vertical straight line is included, the straight line will be distorted.

That is, it adversely affects the received still image. Also, A/D
When converting, in addition to the jitter, the reproduced analog signal is
Noise added during the process of D conversion also has an adverse effect on the received still image.

[Problem to be solved by the invention]

In the above-mentioned conventional technology, in order to eliminate the adverse effect on the received still image, it is necessary to strictly eliminate even the slightest jitter. For this purpose, it is necessary to strictly eliminate rotational irregularities in the disk drive device.

However, there is a problem in that the device becomes very expensive in order to satisfactorily eliminate rotational irregularities in the disk drive device. Furthermore, there has been no effective solution to the noise added during the A/D conversion process of the reproduced analog signal.

The present invention aims to eliminate the adverse effect on received still images due to jitter caused by uneven rotation of a disk drive device, without adding expensive equipment, and furthermore, it aims to solve the problem of the process up to A/D conversion of analog still image signals. The purpose is to reduce the effect of noise added in

[Means to solve problems]

For the above-mentioned purpose, the present invention provides a reproduction means for reproducing a still image signal recorded on a disk-shaped medium and outputting it as a digital signal; an addition means for adding digital signals of pixels at the same location of the image multiple times; and digital image signal processing means for performing digital image signal processing on the digital still image signals added by the adding means.

[Effect]

According to the present invention, in order to obtain one frame of the original picture (digital original picture signal for digital signal processing), it is reproduced multiple times,
Since the plurality of signals are obtained by adding them, the influence of uneven rotation is averaged and improved according to the number of additions. Random noise added to the process from reproduction to A/D conversion is also improved according to the number of additions.

〔Example〕

FIG. 2 shows an example in which the digital image signal processing device of the present invention is applied to a transmission device that transmits images to a remote receiving device using a telephone line.

A still image recorded in analog on the FTP disk 201 is reproduced by a magnetic head 202 and a preamplifier 203, and demodulated by a demodulation circuit 2-04. Various signal processing is then performed by the process circuit 205.

For example, processing such as low-pass filtering, gamma correction, and clamping is performed. The analog signal processed by the process circuit 205 is digitized by the A/D converter 206, and the scanning line data to be transmitted is recorded in the line memory 207. A direct memory access (DMA) controller 208 transfers data to a central processing unit (CP).
U) It enables high-speed data transfer by directly connecting data between memories or between memory and each component such as llorJl without going through 210. In this embodiment, there are two channels, and channel 1 is D/A data in random access memory (RAM) 209
Output to converter 212. Channel 2 transfers the output of line memory 207 to RAM 209. Channel 1 has higher priority than channel 2. A read-only memory (ROM) 211 stores programs and a look-up table (LUT) for gamma correction. A central processing unit (CPU) 210 controls the entire transmission device and performs calculation processing.

The operation of the electric transmission device with the above configuration will be explained using FIG. 3.

FIG. 3 is a block diagram showing the flow of processing digital image signal data when performing addition processing four times. In FIG. 3, A-F indicate processing contents.

In this embodiment, data processing is performed in units of l scanning line data. RAMs 301 to 310 represent specific areas of RAM 209, and the necessary capacity is ensured.

The scanning line data of the image that is about to be transmitted now is on the floppy disk 201 --- Magnetic head 202 ---
--Preamplifier 203--Demodulation circuit 204--
...The CPU 210 is configured to output an interrupt signal to the CPU 210 when the data is A/D converted by the A/D converter 206 via the process circuit 205 and written to the line memory 207. Data is transferred from the line memory 207 to the RAM 301 using channel 2 of the DMA controller 208.Next, the floppy disk 201-1--Magnetic head 202--
Preamplifier 203...-Demodulation circuit 204°・°・°
When the data of the same scanning line as the scanning line data is A/D converted by the A/D converter 206 via the process circuit 205 and written to the line memory 207, the C
It is configured to output an interrupt signal to the PU210. The CPU 210 uses channel 2 of the DMA controller 208 to read data from the line memory 207 to the RAM 302.
transfer data to. Thereafter, data of the same scanning line is sequentially transferred to the RAMs 303 and 304 and stored in the same manner. This process is the process shown in FIG. 3A. Next, the data stored in the RAMs 301 to 304 are added for each corresponding pixel and stored in the RAM 305. This process is shown in FIG. 3B. Next, the CPU performs arithmetic processing on the l scanning line data that has been added four times and is stored in the RAM 305, and the even numbered scanning line data is stored in the RAM 306 and the odd numbered scanning line data is stored in the RAM 307. Ru. This process is shown in FIG. 3C. Dropout of data stored in the RAM 306 or 307 is detected by a dropout detection means (not shown). RAM
When a dropout is detected in either RAM 306 or 307, processing is performed to complement it with the data of the corresponding pixel in the other RAM. The scanning line data with dropouts complemented is stored in the RAMs 306 and 307, and the CPU 210 performs gamma correction on this data through digital processing. Digital gamma correction is in ROM
This is done using 211 LUTs.

Depending on the transmission system, the main scanning direction may be different, and in that case, the data is stored in the RAM 308 after processing for converting the scanning direction. This process is the process shown in the third diagram.

After the data in the RAM 308 is modulated for transmission, even-numbered scanning line data is stored in the RAM 309 and odd-numbered scanning line data is stored in the RAM 310.

This process is the process shown in FIG. 3E.

Channel l of the DMA controller 208 is the RAM 30
9 and RAM 310 alternately and repeatedly for each scanning line D/
The signal is output to the A converter 212, and the D/A converter 212 outputs a continuous analog scanning line signal (analog image signal) suitable for electric transmission. This process is the process shown in FIG. 3F.

FIG. 4 is a time chart of processes A to F in FIG. In FIG. 4, the bottom row of each block indicates the scanning line number.

The upper row in FIG. 4 is the process (F), which is executed by channel 1 of the DMA controller 208. The middle row is the processing of (B), (C), (D), and (E), and the CPU2
10.

The lower row is the process of (A), and the DMA controller 2
Performed by Channel 2 of 08.

These upper, middle, and lower processing blocks can proceed simultaneously.

The (N-1)th scanning line data is sent to the DMA controller 2.
At the same time (F) started by channel l of 08, the (N+1)th scan line data is transferred to the DMA controller 2.
R from line memory 207 by channel 2 of 08
Each of the data is directly stored in the AM 301 to RAM 304.

(A) CPU 210 is stored in RAM 208 (N)
The RAM 309 performs modulation on the th scanning line data.
(RAM 310). (E) After that, confirm that the (N+1)th scanning line data has been stored from RAM 301 to RAM 304, and perform averaging, dropout correction, digital gamma correction, and scanning direction conversion on the (N+1)th scanning line data. RAM
308.

(B) (C) (D) By repeating these processes, it is possible to create a signal for electronically transmitting the image recorded on the floppy disk.

The above explanation is based on the assumption that the image signal is sequentially scanned, and the actual image signal is as follows.

In the case of a frame image signal, odd lines correspond to odd fields, and even lines correspond to even fields.

Therefore, it is necessary to make a correspondence between the odd-even fields and the odd-even lines. In addition, in the case of a field image signal, since the field image signal itself has only half the image information of the screen, it is necessary to complement the lines in order to complete the image. Therefore, the processing of A, B, C, and D is performed once for two transmission lines.
Just do it once.

FIG. 5 shows a time chart showing the timing of processing in the case of a field image signal.

〔Effect of the invention〕

As described above, in the present invention, after digitizing a still image signal recorded on a floppy disk, the signal obtained from a single field (or frame) is averaged over several fields (or frames). It is possible to obtain high-quality still image data because the effects of jitter and noise that occur during playback can be significantly reduced compared to digital image data that is generated.

[Brief explanation of the drawing]

1 and 2 are block diagrams showing the configuration of the present invention,
FIG. 3 is a block diagram showing the signal flow in the embodiment,
FIG. 4 is a time chart showing the timing of signal processing in one embodiment. FIG. 5 is a time chart showing the timing of signal processing in another embodiment. 101, (Explanation of symbols of main parts) 201--1・----1・-Floppy disk magnetic head preamplifier demodulation circuit A/D converter adder memory Applicant Nikon Co., Ltd. Agent Patent attorney Takao Watanabe

Claims (1)

[Claims] (1) In an apparatus for digital signal processing of a still image signal recorded on a disk-shaped medium as an analog signal, a reproduction means for reproducing the still image signal recorded on the disk-shaped medium and outputting it as a digital signal; It is characterized by comprising an adding means for adding digital signals of pixels at the same location of an image a plurality of times, and a digital image signal processing means for performing digital image signal processing on the digital still image signals added by the adding means. Image signal processing device.