JP3799096B2 - Imaging device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image pickup apparatus that can process an imaged signal to obtain an imaged signal that is converted into a special image. Specifically, the captured signal is processed and only the contour portion is displayed superimposed on a halftone background, so that a pastel image having only the contour portion can be displayed.
[0002]
[Prior art]
Some imaging devices are known that can process captured signals and convert them into special image signals such as mosaic images. If, for example, only the contour portion of the subject is extracted from the special image and is superimposed on the background of the halftone brightness, a soft pastel image (hereinafter referred to as a pastel image) is obtained.
[0003]
For example, the original image as shown in FIG. 7A shows a bright and dark building, but this is processed to display all the backgrounds at a halftone level. When superimposed, a special image is obtained in which the outline portion of the building is projected on a single halftone background from which the contrast is removed as shown in FIG. Since the background is halftone, this special image is a pastel image.
[0004]
[Problems to be solved by the invention]
When a special image as shown in FIG. 7B is obtained in addition to a normal image signal when an object is imaged, this image pickup apparatus can be used with a sense of play, which is convenient.
[0005]
Conventionally, such a special image that obtains a mosaic image currently exists, but an apparatus for obtaining a pastel image as shown in FIG. 7B has not yet been developed.
[0006]
The present invention proposes an imaging apparatus that is configured to obtain this pastel image among special images and to obtain an optimum pastel image.
[0007]
[Means for Solving the Problems]
In order to solve the above problem, an imaging apparatus according to the present invention produces a luminance signal from the image signal of the captured arbitrary subject, emphasizing luminance outline of the object to extract a contour component from the luminance signal An imaging device that outputs a signal, and extracts only one of a positive contour component or a negative contour component from the contour component, and superimposes the extracted one contour component on a predetermined halftone level And a signal processing unit that outputs the luminance signal obtained as a luminance signal for emphasizing the contour portion of the subject .
[0008]
According to the imaging apparatus according to the present invention, when the special image conversion display mode is selected, a predetermined gray level instead of the luminance signal generated from the shooting No. Zoshin is selected as the background level. Further, the horizontal and vertical contour components are extracted from the luminance signal, and among the extracted contour components , in this example, the negative contour component is added to the halftone level. This added output is output as a luminance signal, and a color component is added to the luminance signal to form a final pastel image.
[0009]
By using a level representing a halftone as the background level, the entire image becomes pastel. Accordingly, it is possible to obtain a pastel image in which the contour portion of the subject is emphasized and projected on a single halftone background from which light and dark are removed.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Subsequently, an embodiment of the imaging apparatus according to the present invention will be described in detail with reference to the drawings.
[0011]
FIG. 1 shows an embodiment of an imaging apparatus 10 according to the present invention having a special image conversion processing function.
[0012]
In the figure, a subject 11 is converted into an electrical signal (imaging signal) by an imaging element 13 such as a CCD via a lens system 12. In this example, as shown in FIG. 2, a color filter arranged in a preceding stage of the image sensor 13 is a complementary color filter having a checkered pattern.
[0013]
When the color filter of the complementary color checkered pattern is used, the luminance signal and the color signal are formed using the checkered pattern every two stages. In the figure, lines read simultaneously from the first two stages are shown as R lines for convenience, and lines obtained simultaneously from the next two stages are shown as B lines.
[0014]
The imaging signal (R line signal and B line signal) output from the imaging device 13 is subjected to AGC in the sampling hold circuit and AGC circuit 14 in order to adjust the dynamic range during sampling and digital conversion. Thereafter, it is converted into a digital signal by the A / D converter 15.
[0015]
The digitized imaging signal is supplied to the signal processing unit 20. In the signal processing unit 20, a defect correction circuit 21 is first provided, and a signal defect based on a CCD defect is corrected using front and rear pixels and upper and lower pixels. Thereafter, the image pickup signal H1D which is supplied to the delay circuit 22 having a delay element (or may be a delay line) and delayed by 1H (one horizontal period) and the image pickup signal H2D delayed by 2H are output.
[0016]
These imaging signals Sa (H1D, H2D) are supplied to the luminance signal processing circuit 30 and the color signal processing circuit 24, and the corresponding luminance signal Y and color signal C are generated. The signal processing circuit 20 is managed by a control unit 25 constituted by a CPU, or signal processing is performed, so that the signal processing unit 20 is provided with interface circuits for a plurality of processing systems provided therein, not shown. It has been.
[0017]
In the embodiment, a gain adjusting circuit (not shown) provided in the color signal processing circuit 24 is adjusted so as to obtain a predetermined gain when generating a pastel image, as will be described later, and a diaphragm provided in the optical system 12. The adjustment circuit 26 is controlled by the control unit 25. In the case of a pastel image, the color saturation is set to be higher than usual so that a color close to the pastel image can be reproduced.
[0018]
In addition, the aperture adjustment circuit 26 is controlled to open the aperture more than during normal imaging. This is because, when obtaining a pastel image, the contour portion of the subject that occupies a large proportion of the screen is an important element rather than displaying the subject in detail, so that this contour portion can be extracted as reliably as possible. The aperture is opened to a level that saturates during normal imaging.
[0019]
FIG. 3 shows a specific example of the luminance signal processing circuit 30 described above. An imaging signal H1D delayed by 1H is supplied to the terminal 31, and an imaging signal H2D delayed by 2H is supplied to the terminal 32. The imaging signal H1D delayed by 1H is band-limited by the digital low-pass filter 33, whereby a low-frequency imaging signal Sb necessary for image display is extracted. This image pickup signal Sb is supplied to a horizontal contour extraction circuit (H aperture control) 34, and a contour component Pa in the horizontal direction is extracted from the image.
[0020]
Similarly, the 1H-delayed imaging signal H1D and the 2H-delayed imaging signal H2D are supplied to the vertical direction contour extraction circuit (V aperture) 35 to extract the vertical contour component Pb.
[0021]
The contour components Pa and Pb relating to the horizontal direction and the vertical direction are supplied to a contour emphasis circuit (apercon effect circuit) 40. In the normal contour correction mode, the combined contour component Pd is output, and in the pastel image mode. After the gain adjustment, only one of the positive contour component and the negative contour component is selectively extracted. In this example, as will be described later, only the negative side contour component Pd ′ is extracted.
[0022]
These contour components Pd and Pd ′ are supplied to the gamma correction circuit 50 together with the low-frequency imaging signal Sb and subjected to gamma correction (γ correction). The gamma-corrected imaging signal Sc is further supplied to the second contour correction circuit (apercon) 60. The white level side contour components supplied to and compressed by gamma correction are added again so that the contour enhancement characteristic is uniform over the entire region from the white side to the black side. In this process, the contour correction signal Pi generated by the contour enhancement circuit 40 is used.
[0023]
The image signal Se whose contour component has been readjusted is subjected to white fader or black fader adjustment in the subsequent fader 61 to obtain a final luminance signal Y subjected to appropriate signal processing such as contour correction.
[0024]
FIG. 4 shows specific examples of the above-described contour emphasizing circuit 40 and gamma correction circuit 50. The adding circuit 40 is provided with contour components Pa and Pb (FIGS. 5A and 5B) in the horizontal and vertical directions. In 41, the contour components Pa and Pb are added. The added contour component Pi is supplied to the multiplier 42 and multiplied with the gain adjustment signal Pe supplied from the terminal 43. The multiplication by the gain up in what is done in order to emphasize the contour component (Fig. 5C), in this example also used as a signal Pi for reconditioning for contour enhancement.
[0025]
The contour component Pf which is a multiplication output is supplied to both the OR gate circuit 44 and the AND gate circuit 47, and the gate state of the AND gate circuit 47 is controlled by the OR gate output Ph.
[0026]
The gate circuits 44 and 47 are gate circuits for outputting the contour component Pf itself in the normal contour enhancement mode and outputting only the negative contour component Pd ′ in the pastel image mode.
[0027]
For this purpose, the most significant bit MSB indicating the positive or negative polarity of the digitized contour component Pf is supplied to the OR gate circuit 44 and the mode signal Pc from the terminal 45 is given. The mode signal Pc is a signal for selecting whether to use the pastel image mode or the normal contour enhancement mode, and is low level in the normal contour enhancement mode and high level in the pastel image mode. Shall.
[0028]
The mode signal Pc is inverted by the inverter 46 and then supplied to the OR gate circuit 44 as its gate signal. On the other hand, in this example, when the MSB bit of the contour component Pf is “0”, the contour component Pf is a positive component, and when it is “1”, it is a negative component. Therefore, the relationship (truth value) of the mode signal Pc, the contour components Pf and Pf with the MSB and the gate output Pd (Pd ′) is as shown in FIG.
[0029]
As is apparent from the truth table of FIG. 6, since the gate input level becomes high level in the normal outline emphasis mode, the OR gate output Ph becomes high level regardless of the value of MSB. As a result, the contour component Pf passes through the AND gate circuit 47 as it is. As a result, a positive / negative contour component Pf (= Pd) is output.
[0030]
On the other hand, when the pastel image mode is selected, when the MSB bit is “1”, that is, when it is a negative value, the gate output Ph becomes high level, so the contour component Pf at that time is gated. The That is, the contour component Pd ′. When the MSB bit is “0”, the gate output Ph is inverted to the low level, so that the gate is not gated at this time, and the output of the gate circuit 47 becomes zero.
[0031]
Therefore, by this gate processing, a positive / negative contour component Pd is obtained in the normal contour emphasis mode, and a contour component Pd ′ having only a negative component is obtained in the pastel image mode. The reason why only the negative component is used in the pastel image mode is that the background has a single halftone level, as will be described later, so that the negative contour component is darker than the background to enhance the contour. It is necessary to do. This is because, when the positive component is used, the contour is blurred because the contour portion approaches the background level side.
[0032]
Next, the gamma correction circuit 50 will be described in detail with reference to FIG. 4 again.
The gamma correction circuit 50 includes a level switching switch 51, an adder 52 for adding contour components, and gamma correction means 53 for imparting gamma characteristics. The imaging signal Sb itself which is a low-pass output is given to the terminal a side of the switch 51, and a fixed value is given to the terminal b side. The fixed value is for setting the luminance level for projecting the screen at a constant level. In this example, the halftone level is selected. As shown in FIG. 5F, in this example, the value is set to 60 IRE on the IRE (Institute for Radio Engineers) scale.
[0033]
This value is also related to the exposure amount. In this example, the aperture adjustment circuit 26 shown in FIG. 1 is controlled so that the reference exposure value for automatic exposure is set in the pastel image mode, and 60 IRE is obtained when all white is imaged. The iris is adjusted to.
[0034]
The switch 51 is switched by the mode signal Pc, and the terminal a side is selected in the normal outline emphasis mode, and the fixed value on the terminal b side is selected in the pastel image mode. The contour component Pd or Pd ′ is added to the selected signal.
[0035]
For example, in the normal contour emphasis mode, the contour component Pd is added to the image signal Sb shown in FIGS. 5A and 5C, so that the image signal Sb after contour emphasis, which is an addition output, is as shown in FIG.
[0036]
On the other hand, when the pastel image mode is selected, a fixed value (FIG. 5F) is selected and the contour component Pd ′ (E in FIG. 5) for the pastel image is added, so that the pastel image that is the imaging signal at that time is added. The signal Sb ′ is a signal in which the luminance level is reduced only at the contour portion as shown in FIG. Therefore, when this pastel image signal Sb ′ is monitored, a pastel image (FIG. 7B) in which only the contour of the subject is displayed on the background of the halftone level is obtained. When a color signal is added to this, a color pastel image is obtained.
[0037]
In the pastel image mode, the color saturation is set higher than usual so that a more natural color pastel image can be obtained. The adjustment of the saturation degree is achieved by controlling the amplifier gain of the color signal processing circuit 24 to be higher only in the pastel image mode based on the control signal from the control unit 25.
[0038]
In the above-described example, the background halftone level is set to 60 IRE and the pastel image is formed using only the negative component of the contour component. On the contrary, the halftone level is set to be darker and It is also possible to form a pastel image using the contour component of only the above component. In this case, the contour of the subject is projected white on a black background. In this case, the fixed value given to the switch 51 shown in FIG. 4 is set lower than 60 IRE, and the OR gate circuit 44 may be changed to a NAND gate circuit. These can be switched and used, and even if configured in this way, the circuit configuration is not so complicated.
[0039]
【The invention's effect】
As described above, in the imaging apparatus according to the present invention, a pastel image signal that does not exist as a special image can be formed in addition to a normal imaging signal. Therefore, it can be enjoyed as a normal imaging device, and a special image such as a pastel image in which the contour of the subject is projected on a single halftone background from which light and darkness has been removed can be obtained. Can be enjoyed at. That is, an imaging device having a new feature can be provided.
[0040]
When generating a pastel image, the reference exposure value for automatic exposure is controlled to be a predetermined level when all white images are captured, making it brighter than normal, so the contour of the subject can be extracted reliably. It becomes possible to obtain a beautiful pastel image.
[0041]
Furthermore, since the pastel image is formed using a specific contour component, the contour of the subject can be clearly displayed, and a pastel image with a clear contour can be obtained.
[Brief description of the drawings]
FIG. 1 is a system diagram of a main part showing an embodiment of an imaging apparatus according to the present invention.
FIG. 2 is a layout diagram illustrating an example of a color filter.
FIG. 3 is a system diagram showing an example of a luminance signal processing circuit.
FIG. 4 is a system diagram of a main part showing further details of a luminance signal processing circuit.
FIG. 5 is a waveform diagram showing an example of pastel image processing.
FIG. 6 is a diagram showing a truth table in a pastel image mode.
FIG. 7 is a diagram illustrating a relationship between a normal image and a pastel image.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Imaging device, 20 ... Signal processing part, 24 ... Color signal processing circuit, 25 ... Control part, 26 ... Aperture adjustment circuit, 30 ... Luminance signal processing circuit, 34, 35 contour component extraction circuit, 40 ... contour emphasis circuit, 44, 47 ... gate circuit, 50 ... gamma correction circuit

Claims (3)

An imaging device that generates a luminance signal from an imaging signal obtained by imaging an arbitrary subject, extracts a contour component from the luminance signal, and outputs a contour-enhanced luminance signal that emphasizes a contour portion of the subject,
Only one of the positive contour component and the negative contour component is extracted from the contour component, and a luminance signal obtained by superimposing the extracted one contour component on a predetermined halftone level is used as the contour signal. An image pickup apparatus comprising a signal processing unit that outputs an enhanced luminance signal.   The imaging apparatus according to claim 1, wherein the signal processing unit includes a contour enhancement circuit that enhances the contour component to enhance a contour portion of the subject.   The signal processing unit includes a gamma correction circuit capable of switching between the luminance signal and the halftone level, and superimposing a contour component on the luminance signal and superimposing the one contour component on the halftone level The imaging apparatus according to claim 1, wherein the imaging device is selectable.

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