JPH02305195A - Signal processor for image pickup device - Google Patents

Abstract

PURPOSE:To prevent the amplitude of a picture from being rapidly changed after a pseudo color is removed and to remove the vertical pseudo color in a natural state by detecting a vertical edge part, attenuating the color signal level of the edge part, where the pseudo color is generated, and afterwards, executing low-pass filtering. CONSTITUTION:The size of a VAPC signal, which is obtained in a luminance step removing circuit 104, is decided by an amplitude decider 107 (detecting means) and when the size of the VAPC signal is more than a prescribed level, it is defined as the vertical edge part. Then, an attenuation level signal is selected by a switch and the input signal is attenuated. When the size of the VAPC signal is smaller than the prescribed level, the pseudo color in the vertical edge is removed by outputting the input signal at it is. Since the output signal if a color signal level attenuating circuit 112 prevents color difference gain from being rapidly changed in the vertical edge part to be generated by the operation of the color signal level attenuating circuit 112 inputted to an LPF 113 (band limiting means), the band is limited in a vertical direction. Thus, the pseudo color to be generated in the vertical edge can be prevented.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a signal processing device for an imaging device such as a single-chip color video camera or a single-chip color still video camera equipped with a color separation filter. .

[Conventional technology]

In conventional devices of this type, a solid-state image sensor CCD
(charge coupled device)
(hereinafter referred to as a CCD sensor) is equipped with a color separation filter as shown in Fig. 2(a), and signal processing is performed using the configuration shown in Fig. 8 to finally separate a luminance signal Y and two color difference signals. Usually, RY and BY are obtained.

The luminance signal processing in this conventional method is first
Mg, O obtained using a color separation layer filter as shown in figure (a)
After the automatic gain adjustment (A(3C) circuit 102 performs gain adjustment so that each color signal of r, Cy, and Ye shows an equal response to white, the A/D converter 103 performs A/D
(analog-to-digital) conversion. Furthermore, the second
If the type of color separation filter installed in the same horizontal line is different every 1l-1 (horizontal scanning time), not only the color separation filter shown in figure (a), the bright line and dark line will be separated for each IH. Since there is a problem with the brightness level difference that occurs, the brightness level difference is removed in a circuit 104 for removing the brightness level difference, and then γ conversion is normally performed.

Knem conversion etc. are performed, and a low pass filter (hereinafter referred to as LPF) is applied.
) After limiting the bandwidth at 106.

It performs D/A conversion and outputs it as a Y signal.

Color A 5 Out of processing "C" means that when a CCD sensor equipped with a color separation filter having the arrangement shown in Figure 2 (a) is interlaced scanned, the colors magenta (Mg) and green (Or) are displayed in the odd rows. The signal - is output to the intersection, η, for each pixel,
In the even-numbered columns, cyan (Cy) and yellow (Ye) color signals are outputted in an alternating manner for each pixel. Therefore, if we focus on one pixel, it will have information on only one of the four color signals of Mg, Gr, Cy, and Ye. For example, the second
The part marked with an X in Figure (b) is another GP, Cy.

There is color information for either Ye, but there is no information for Mg or G.
It is necessary to interpolate () the information on Mg at the numbering position indicated by the O symbol with appropriate weighting.

Generally, 4-wire simultaneous readout is 11 times like MO3 type sensor.
If it is a functional element, it is red (R) and edge (G).

i'i (B) (Although it is easy to convert to +E,
For sensors that cannot read simultaneously, such as CCD sensors, a6 il!
An operation called l-grained interpolation, which cannot be converted into an RGB signal without synchronization using an l filter, is always required.

Mg, GP synchronized by complementary 11jJ filter.

For example, the four colors Cy and Ye are RGB as shown in Figure 8.
After being converted into RG and B signals in the conversion matrix circuit 109, the white balance adjustment that is normally performed, γ
After processing such as conversion, the color difference matrix circuit 111 converts into two color difference No. 15 R-Y and B-Y, and finally, after band-limiting in the LPF 113, the D/A converter 1
15 and 116, it is D/A converted and output.

[Problem to be solved by the invention]

However, when synchronizing color signals using an interpolation filter as in the conventional example, vertical contour portions (hereinafter referred to as F
, edges), there was a layer that produced false colors that did not actually exist.

The present invention was made to solve this problem.
It is an object of the present invention to provide a signal processing device for an imaging device that can prevent false colors occurring at the eastbound edge.

(First Step for Solving the Problems) The present invention configures a signal processing device for an imaging device as shown in (1) below in order to achieve 1) L1 objective.

(1) A detection means that receives a signal from an image sensor equipped with a color separation filter and detects a superimposed edge portion, an interpolation filter that receives and synchronizes signal 45 from the image sensor, and a signal from the interpolation filter. An imaging device comprising attenuating means for receiving a signal and attenuating the level of the signal according to the output of the first stage of the detection T'', and band limiting means for receiving the output of the cost reducing means and limiting the range. Signal processing equipment for equipment.

(Function) With the above configuration, the fi of the edge portion where vertical false color occurs is reduced.
The i level attenuates gently.

〔Example〕

Hereinafter, the present invention will be explained in detail using examples.

(Embodiment 1) Fig. 1 is a block diagram of a ``4i% 'j-processing device for an imaging device'' according to the first embodiment of the present invention. This is an example of interlaced scanning using a CCD sensor equipped with a color separation filter such as 'J'.

First, the output signal of the CCD sensor lO1 is 1'1 1!
l adjuster 102 makes each number 45 equal to 1 for white.
The gain is adjusted so as to show a good response, and then the A/D converter 203 converts the A/D at a timing synchronized with the read clock.
D-converted. This A/D change X for later color processing
*The device 103 has good linear characteristics. It is desirable to use 8 bits or more in terms of FA conversion error.

This A/D converted digital amount becomes an input signal to the luminance signal processing section and the color signal processing section.

First, the luminance signal processing section removes the luminance level difference. Based on the reason that brightness steps are noticeable in flat areas with many low-frequency components and less noticeable in edge areas with many high-frequency components, low-pass filtering and bypass filtering are performed on the output signal of the A/D converter 103, and the output signal is filtered using a bypass filter HPF. If the vertical edge (hereinafter referred to as VAPC) signal is lower than a predetermined level, it is regarded as a luminance step part with many low frequency components, and a signal obtained by removing the luminance step obtained by LPF is output, and the VAPC signal is lower than the predetermined level. If it is larger than the level, the A/D converter 10 considers it to be an edge part with many high frequency components and does not perform low-pass filtering.
The output signal of step 3 is output as is.

After that, processing such as γ conversion and Knee conversion, which are normally performed, is performed, horizontal band -1 limit is applied by LPF 106, D/A conversion is performed by D/A converter 114, and the signal is output as a Y signal.

Next, in the color signal processing section, the output signal of the A/D converter 103 is input to an interpolation filter 108, subjected to two-dimensional interpolation in the vertical and horizontal directions, and is synchronized for each read clock. Gr, Cy.

There will be 4 signals of Ye. These four signals are input to the RGB conversion matrix 109, converted into RGB signals, and then subjected to the normally performed white balance adjustment, γ conversion, etc., to the color difference matrix circuit 1! ! It becomes a human signal. The signal converted into a color difference signal by the color difference matrix circuit 111 is input to a color signal level attenuation circuit 112 in order to remove false colors generated at vertical edges.

The operation of the color A3 level attenuation circuit 112 will be explained below. The color signal level g rising circuit 112 outputs a human input signal and an attenuation level signal by switching between them depending on the magnitude of the VAPC signal. That is, the magnitude of the VAPC signal obtained by the r4 degree membrane step removal circuit 104 is determined by the amplitude determiner 107 (detection means), and when the magnitude of the VAPC signal exceeds a predetermined level, it is regarded as a vertical edge portion, and the switch is activated. Select the attenuation level signal to attenuate the input signal level, and
When the magnitude of the APC signal is smaller than a predetermined level, false colors at vertical edges are removed by outputting the human input signal as is.

For example, when the attenuation level signal of the color signal level attenuation circuit 112 (attenuation means) is set to zero, the gains G, -, , G, -Y of the two color difference signals at the vertical edge portion are GR-Y.
= O, QB-Y = O. 'Next, the output signal of the color signal level attenuation circuit 112 is passed through the LPF.
113 (bandwidth limiting means) In order to prevent rapid changes in color difference gain at vertical edge portions caused by the operation of the color signal level attenuation circuit 112, vertical band limiting is performed.

The LPF 113 is configured, for example, as shown in FIG.
The output signal of the memory 601 is set as the signal of interest C1, and its IH
If the signal after ii is Cn-1+Cnil, the coefficient multiplier 6
When the coefficient of 03,605 is set to 1/4 and the coefficient 'a604 (D coefficient fr l / 2), an output signal is sent to the output side of the adder 606. In this embodiment, the output signal of FIG. Two systems of LPFs having such a configuration are used to band limit the R-Y signal and B-Y (No. 3-).

As an example.

[”CK-t, Cx-+, CK, C+
c, +, CK, 2-], the R-Y signal level is [...-60, 60, 40, -40, -80----
A case will be described in which the B-Y signal level is 1 and an edge is detected in the CK, CK, and 1 portions.

In this case, when the attenuation level signal is set to zero, the output R-Y signal of the color signal level attenuation circuit 112 becomes [---60, 60, 0, 0, -80-...
・], and the B-Y signal becomes [・---140, -140, 0, 0, -80-], and if the color is left as it is, the color Z/signal 1 noher will change rapidly and the lfl raw image will be affected. Since the naturalness remains, the configuration 1. in Figure 1j. ,, PF gives color 1 (F); D range limit book)) - that is, CK-3= CK-2, CK
□ =C□.

Then, due to i and P F in the configuration of formula (A), R, -Y
(No. i is [...-60, 45, 15, -20, -60"...
...] and the five-pronged B-Y Jin~ number is
It is possible to prevent the unnaturalness of the raw image due to the color difference caused by 2 (2 sudden changes in the 11 level).

In the configuration example of FIG. 6, the number of taps of the LPF is three, but the number of taps may be arbitrarily changed depending on the desired frequency band.

Finally, ■, the color difference I5 output from PF 113.
The numbers RY and B-Y are D/A converted and output.

(Second example) In the first actual journey example, i, i, color i, -: call sincerity && circuit, 11
2 configuration GI, IC direct, 'T-Tsuji part has two colors;'
1.4: The number was set to ip net zero, but the actual example is a two color difference 7 trix circuit 11 as shown in Figure 3.
Coefficient unit 30 for output number 5 R-”/, B-Yl, 7 of 1
2.303° and 304 are set, and one novel of attenuation is set with the threshold value and coefficient as shown in FIG.

That is, in this embodiment, m4 is
By attenuating the color difference signal in stages with characteristics like J and R in the figure, sudden changes in the color difference gain are avoided, and it is effective in removing false colors in the small straight 9th and third corners. The coefficient of the coefficient unit in this example is α
-1/2. When β=1/4° and γ=1/8, the switch section can be configured as shown in FIG. In other words, if W is a 4-bit signal, then in the switch 501, the ■ part is α, the ■ part is β,
The part (■) becomes γ.

Note that the number of coefficient units is not limited to three, and the coefficient value α.

β, Y...- are coefficients that satisfy the condition 4' [0 <------< γ × β × α × 1. Threshold Th, ~T
h4 can also be set arbitrarily.

Further, the BY signal in FIG. 3 is also subjected to the same processing as the R and -Y signals, and the two color difference signals become the input signals of the LPF 113. Below, the same processing as in the first embodiment is performed.

(Third Embodiment) In each of the embodiments 1- below, the C1 vertical edge portion is attenuated with respect to the color difference signal, but in this embodiment, the attenuation is performed with respect to the output RGB signal of the RGB conversion matrix circuit 109. This is used to attenuate vertical edges.

As shown in FIG. 7, the output signal of the RGB matrix 109 is subjected to white balance adjustment and γ compensation iE at 110.
12 has a similar configuration, and the input terminal is manually powered by a 70m color signal level attenuation circuit with RG, B, and the VAPC (social level level 3 and human power signal are switched depending on the size of 3). It is output as an RGB signal with color removed.

After that, the rapid gain change caused by the operation of the color signal level attenuation circuit 701 is observed in the configuration 1. shown in FIG. , PF 113 having three systems performs the same operation as in the first embodiment. It is prevented by two things. LPF113
The output is inputted to the color difference matrix circuit 111, converted into color difference signals RY and BY, and then output after D/A conversion.

, : Attenuating the signal at the vertical edge portion at the R, G, B signal stage is also effective as a countermeasure against false colors.

Note that if the configuration of the color signal attenuation circuit 701 of this embodiment is the configuration of the 6A attenuation circuit in FIG. 3, f? , GB low signal attenuation is effective on the same line.

(Other Examples) Below. This was an explanation of the case where the color separation filter array shown in Fig. 2(a) was interlaced scanned using a frame storage voltage, but the color separation filter arrangement shown in Fig. 9(a) was scanned in a frame manner. Even if you perform A/D conversion on a non-interlaced or interlaced scanned signal with 1,000-bit storage and then output the data stored in the frame memory and perform color synchronization, two-dimensional interpolation will The present invention can be implemented because it produces false colors on vertical edges.

Furthermore, when the color separation filter array shown in FIG. 9(a) is read out in a two-pixel mixture in field accumulation mode, and when the color separation filter array shown in FIG.
), which is obtained when a color filter array with two different color filters attached to one pixel is used as an interlace set.
0 signal C,=Mg+Cy, C2=Gr+Ye, C3=M
Even when synchronization is performed using an interpolation filter for H+Cy and C4=Gr+Ye, the present invention can be implemented since false colors occur at vertical edges.

The above explanation was based on digital processing, but the above-mentioned IH memory is used as an IH delay, and the coefficient multiplier is used as an appropriate kr!
It goes without saying that the present invention can also be implemented in analog processing by simply changing to a width scale.

Furthermore, although the description has been given using a CCD sensor, the present invention is not limited to this, and the signal IAJIF of an imaging device using another image sensor -f that requires synchronization of color signals by an interpolation filter. It can also be connected to the device.

(Effects of the Invention) As described above, according to the present invention, vertical edge portions are detected, the color signal level of the edge portion where false color occurs is attenuated, and then low-pass filtering is performed to remove false color. It is possible to prevent sudden changes in image amplitude and remove vertical false colors in a natural manner.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the first embodiment of the present invention, Fig. 2 is a diagram showing a color separation filter array, Fig. 3 is a block diagram of the main part of the second embodiment of the invention, and Fig. 4 is attenuation. A diagram showing the levels,
Fig. 5 is a block diagram of the attenuation circuit, Fig. 6 is a block diagram of the low-pass filter, Fig. 7 is a block diagram of the third embodiment of the present invention, Fig. 8 is a block diagram of the conventional example, and Fig. 9 is a block diagram of the other example. FIG. 2 is a diagram showing a color separation filter array of FIG.

Claims (1)

[Claims] (1) A detection means that receives a signal from an image sensor equipped with a color separation filter and detects a vertical edge portion, an interpolation filter that receives and synchronizes the signal from the image sensor, and a signal that receives the signal from the interpolation filter. Signal processing for an imaging device, comprising attenuation means for attenuating the level of the signal according to the output of the detection means, and band limiting means for receiving the output of the attenuation means and limiting the band. Device.