JPH04126487A - Video signal processing unit - Google Patents

Abstract

PURPOSE:To prevent production of dispersion in a luminance signal level for each horizontal line by using a correction means so as to correct a vertical contour based on 1st field and 2nd field signals read from a signal storage means and corresponding to each other. CONSTITUTION:A separated luminance signal YH and chrominance signals R, G, B are inputted to a process circuit 12, in which they are gamma-corrected and the processed signals are outputted as a luminance signal, a G signal and a color difference signal. Then a signal by one field is frozen and stored in field memories 14, 15 through a memory controller 13. After freeze to the memory, the vertical contour correction is implemented at read. with respect to the G signal, signals of same lines in the 1st and 2nd fields are read simultaneously from the memories 14, 15 through the controller 13. Moreover, as to the luminance signal, it is read sequentially in the interlace form from the 1st field in the same time series as that at memory write.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a video signal processing device such as a still video camera.

(Prior Art) Conventionally, there is a color imaging device using a frame readable solid-state imaging device having the configuration shown in FIG.
It is a striped or mosaic pure color type as shown in a) and (b).

In FIG. 3, numeral 38 is an optical system including a lens, an aperture, an optical low-pass filter, etc., and the optical image inputted from the optical system is processed by a color array filter 3 as shown in FIG.
9 and is photoelectrically converted into an interlaced frame signal by the solid-state image sensor 40. The solid-state image sensing device used in this case has a configuration as shown in FIG. 5, which is a typical example of an interlaced type. Here, interlaced scanning will be explained. As shown in Fig. 4, the light-receiving elements and color filters are configured such that one color filter corresponds to two pixels in the vertical direction, and one pitch corresponds to one pixel in the horizontal direction. The upper half and the second field share the pixels of the lower half. In both the second fields, various signal processing such as color separation can be performed completely equally.

That is, as shown in FIG.
As the horizontal line signal of the row, only the upper half pixels of the color filter elements of the first row vertically divided into two pixels are selected and read out, and the horizontal line signal of the second row is the next one. The pixels in the upper half of the color filter element in the second row are read out. Thereafter, the pixel columns in the upper half of the color filter elements in each row are sequentially read out in the same manner. In the second field, similarly to the first field, the pixel columns in the lower half of each color filter element are sequentially read out. In Figure 5, the selection of the upper and lower pixel columns of the color filter element for each field is as follows:
φ1 of the vertical transfer gate pulse 56. This is done by φv2. Each selected horizontal pixel column is output to each vertical register group 55, transferred to each horizontal shift register 54 during each horizontal retrace period, and then transferred one pixel at a time by horizontal transfer lock 57 φh. The signals from the shift register are sequentially output from the terminal 60 through the output amplifier 59.

The color filter array in Fig. 4 has a configuration in which strings with high visual sensitivity are arranged every other pixel in the horizontal direction, and red and blue are arranged every other line within one field, so it is possible to combine appropriate neighboring pixels. Although high horizontal resolution can be obtained from the luminance signal, it is difficult to obtain resolution in the vertical and diagonal directions. In addition, in order to prevent false colors occurring in the vertical direction, vertically adjacent color filter elements (two vertically
It is necessary to take a correlation between the pitches). In other words, by using an optical low-pass filter that removes (smoothes) the corresponding spatial frequency component, the vertical resolution also decreases by that amount. Therefore, as shown in the configuration of the conventional example shown in Fig. 3, the vertical resolution corrector stage when using the color filter in Fig. 4 extracts the vertical high frequency components between the field lines of the green signal and A commonly used method is to substitute the vertical high-frequency signal component of the signal.

In FIG. 3, after being photoelectrically converted by the solid-state image sensor 40, the output signal read out from the solid-state image sensor 40 in synchronization with the synchronization signal generated by the synchronization signal generation circuit 42 is as follows.
This is combined with a signal delayed by a time corresponding to one horizontal scanning time in a CCD delay circuit 43, and a color separation circuit 44 outputs a red signal.

Separated into blue and green color signals and a luminance signal Y,
The low-pass filters 45 to 4B limit the band to an appropriate band. Separated luminance signal Y. To correct the vertical resolution reduction, a vertical high frequency signal is extracted by calculation between two horizontal lines of the green signal in the vertical high frequency separation circuit 50, and is added to the luminance signal YH as a vertical high frequency component of the luminance signal. The process circuit 51 obtains a brightness Y'□.

Red is inputted to the process circuit 51 in the correct direction.

Each color signal of blue and green is a color difference signal RY signal by matrix calculation inside the process circuit 51.

It is converted into a B-Y signal, guided along with the luminance signal Y'□ to the color encoder 52, and outputted from the terminal 53 as a television signal.

[Invention or problem to be solved]

However, in the conventional example, a problem arising from the structure of the color filter array is that the spectral sensitivity characteristics vary depending on the position of the color filter elements, which significantly impairs the quality of captured images.

In other words, there is a difference in spectral sensitivity between the edge element sandwiched between the red elements and the green element sandwiched between the blue elements, and the vertical high-frequency signal component of the green signal shown in the conventional example above Although the difference should not occur in areas with strong vertical correlation, it always includes the sensitivity variation, and as a result, it also emphasizes the variation in the luminance signal level for each horizontal scanning line. was.

The present invention has been made in consideration of such circumstances, and it is an object of the present invention to provide a video signal processing device in which the luminance signal level for each horizontal scanning line is uniform, based on the structure of the color filter array described above. The purpose is to

[Means to solve the problem]

In order to achieve the above object, the present invention configures a video signal processing device as shown in (1) and (2) below.

(1) A storage means that receives signals from a solid-state image sensor that reads frames by interlaced scanning and stores signals of a first field and a signal of a second field for one frame, and corresponding signals read from the storage means. A video signal processing device comprising a correction means for performing vertical contour correction based on a first field signal and a second field signal.

(2) a color decoder, a process circuit, a selection means for selecting either the output of the color decoder or the output of the process circuit; A video signal comprising a storage means for storing a field signal, and a correction means for performing vertical contour correction based on the corresponding first field signal and second field signal read from the story storage means. Processing equipment.

[Effect]

According to the configurations (1) and (2) above, variations in the luminance signal level for each horizontal scanning line do not occur based on the structure of the color filter array. Further, according to the configuration (2), it is possible to correct the vertical ring part of a general video signal.

〔Example〕

The present invention will be explained in detail below with reference to Examples.

FIG. 1 shows a block diagram of an "imaging device" that is a first embodiment of the present invention. In the figure, 1 is an optical system for forming a subject image onto the solid-state image sensor surface, including a lens, an aperture,
It consists of an optical low-pass filter, etc. Reference numeral 2 denotes a color filter attached to the light receiving section of the solid-state image sensor, which is similar to that shown in FIG. A CCD image area sensor 3 is a solid-state image sensor, and is driven by the output of a CCD driver circuit 4. The synchronous signal generation circuit 5 is a CCD
Tribar 41 color separation circuit 7. This is a synchronization signal source that collectively supplies timing signals necessary to the memory controller 13 and the like.

6 is a CCDIH (horizontal scanning period) delay line, 7 is a color separation processing circuit, 8 to 11 are low-pass filters for the combined luminance signal and each separated color signal, and 12 is a luminance signal and separated R, G , color difference signal R-Y signal by gamma correction and matrix calculation for B signal, B-Y
This is a process circuit that has functions such as converting signals.

Reference numerals 14 and 15 designate buffer memories for one field each of the first field and the second field, into which the luminance signal, G signal and color difference signal which are the output signals of the process circuit 12 are input. 16 on the output side of the field memory 14.15 is a vertical high frequency separation circuit;
6 has the 1st. The G signals of both second fields are simultaneously read out from the memories 14 and 15 and input. 17 is an adder that adds the p value output of the vertical high frequency separation circuit 16 and the luminance signal Y; this addition output Y' and the color difference signals R-Y, B- read out from the memory 14.15;
The Y signal is input to the color encoder 18 and finally output from the terminal 19 as a video signal.

Based on the configuration of the above embodiment, the operation of each part will be explained.

The configuration of separating the luminance signal and each color signal from the optical system 1 and the output of the low-pass filters 8 to 11 and the operation process of signal processing are the same as those of the conventional example shown in FIG. 3, and are as described above. Separated luminance signal Y. The R, G, and B signals, which are each color signal, are input to the process circuit 12, each subjected to gamma correction, and then output as a luminance signal, a G signal, and a color difference signal.
5, one frame is frozen and stored through the memory controller 13.

After freezing into memory, vertical contour correction is performed on readout.

Regarding the G signal, the same line signals of the first and second fields are simultaneously read out from the field memories 14 and 215 through the memory controller 13, and regarding the luminance signal, they are read out sequentially from the first field simultaneously with the memory writing. This is done while reading out using interlaced scanning.

As for the specific calculation contents, the first field (when reading the luminance signal, for example, if it is the nth row, the vertical high frequency separation circuit 16 receives Gln, which is the G signal of the first field, the nth row, and the second G2 which is the G signal of the field nth row
ゎ is read out at the same time, and the difference signal (Gln-02n)
A component proportional to is output from the vertical high frequency separation circuit 16 as a calculated value. On the other hand, when reading the luminance signal of the second field, a component proportional to (G2.-Gln) is output as a calculated value.

These calculation outputs are supplied to the adder 17 as a vertical high-frequency correction signal, and the luminance signal Y is corrected.

Here, unlike the correction signal shown in the conventional example, the created vertical contour correction signal is (
No. 3, that is, it is formed by calculation from the signals of two pixels of the G element in the same color filter array sandwiched between the R or B color filter elements, so it is similar to the problem explained in the conventional example above. There is no influence from variations in sensitivity of the G signal.

FIG. 2 shows a block diagram of a "video signal processing device" which is a second embodiment of the present invention.

The configuration up to the vertical contour correction portion using field memory and color encode output is the same as that of the first embodiment shown in FIG. In particular, in addition to the process circuit 22 similar to that shown in FIG. 1, a color decoder 21 and a low-pass filter 23 that limits the luminance signal output from the color decoder 21 to a horizontal frequency band comparable to that of the G signal are provided.
The point is that a four-channel selector 27 is provided for selecting either the signal from the process circuit 22 side or the signal from the color decoder 21 side.

The configuration of the second embodiment is such that by combining a new human-powered device with the input stage of the field memory, it can be used not only as part of the signal processing of the imaging device, but also easily and for various purposes. This is an extension of the first embodiment so that it can be used as a signal vertical contour correction device.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to suppress differences in brightness levels due to variations in spectral sensitivity based on the structure of the color filter array, and to obtain imaging quality with natural resolution and less false signals in the vertical direction. Further, according to the invention of claim 2,
The contour correction means can be easily used for various purposes such as externally input video signals.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the first embodiment of the present invention, Fig. 2 is a block diagram of the second embodiment of the invention, Fig. 3 is a block diagram of the conventional example, and Fig. 4 is a block diagram of the color filter of the image sensor. Sequence diagram, 5th
The figure is a configuration diagram of a solid-state image sensor capable of frame readout using interlaced scanning. 14゜5...Field memory 6...Vertical high frequency separation circuit 7---Adder

Claims (2)

[Claims] (1) A storage means that receives signals from a solid-state image sensor that reads frames by interlaced scanning and stores signals of a first field and a signal of a second field for one frame, and corresponding signals read from the storage means. 1. A video signal processing device comprising: correction means for performing vertical contour correction based on a first field signal and a second field signal. (2) a color decoder, a process circuit, a selection means for selecting either the output of the color decoder or the output of the process circuit; The present invention includes a storage means for storing field signals, and a correction means for performing vertical contour correction based on the corresponding first field signal and second field signal read from the storage means. Features of video signal processing device.