JP2001203874A - Image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image pickup device, with which information such as date/time, place or photographing equipment can be written in an image file, so as to make it difficult to revise. SOLUTION: For the image pickup device of generating an image signal containing a watermark, this device is provided with a pixel array locating plural pixels 31 for converting incident light to an electrical signal and a change part for changing the output signal of a specified pixel group 32 in this pixel array only slightly in respect to the output signals of pixels, except for this specified pixel group.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus having a watermark function capable of specifying an image pickup apparatus that has captured an image from the captured image.

[0002]

2. Description of the Related Art A technique for watermarking an image captured by an image capturing apparatus has been known. This conventional watermarking technique will be described from two viewpoints.

[0003] One is a technique for adding a watermark that is hard to be seen by humans in order to protect an image or the like having a portrait right copyright, and the other is to prevent unauthorized use of a computer system or the like. In this example, a manufacturing number serving as a unique ID is entered in a CPU or the like, and this unique ID can be referred to from an external circuit and a network. The watermark in such an image utilizes the characteristic of zero signal degradation, which is a characteristic of digital technology, and the watermark is preserved even by illegal copying.

In the latter case of a unique ID such as a CPU, there is a risk that a manufacturer of the CPU or the like or a third party may infringe on the rights of a user of the computer system including the CPU or the like. I have.

[0005] In addition, in the former watermark, in addition to the pattern for protecting the portrait right copyright, a pattern for specifying a system or a person (Japanese Patent Laid-Open No. Hei 5-219353) and date information (Japanese Patent Laid-Open No. Hei 10-290359). ) Or GPS
It is also known to record position information by using.

[0006] Images taken using digital technology have not been effective as legal evidence for a long time because they can be easily modified. is there.

[0007]

However, in order to create legal evidence, it is necessary that the date and time, place, photographer, photographing equipment, and the like be clear. Considering distribution on the Internet or the like, it is desirable that the image file is included in the image file.

The date and time can be easily realized by using a timer and a calendar function built in a digital still camera (digital camera) which is one of the photographing devices.

The location can be read from the image, or the latitude and longitude can be written into the image file using the GPS function described above.

The photographing device can be distinguished by, for example, putting a serial number which is a manufacturing number in a digital camera and writing it in an image file.

Such information is usually written in an area other than the image data such as a header attached to the image file. However, such a file structure makes it very easy to modify such a file, resulting in the above-mentioned legal material becoming less grounded.

Also, there is a file structure that does not have an area such as a header, and it is difficult to secure the area and write the information at present, when various compression formats are scattered.

Accordingly, the present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an image pickup apparatus capable of writing information such as date and time, place, and photographing equipment in an image file without modification. That is.

[0014]

Means for Solving the Problems To solve the above-mentioned problems,
In order to achieve the object, an image pickup apparatus according to the present invention includes a pixel array in which a plurality of pixels for converting incident light into an electric signal are arranged, and an output signal of a specific pixel group in the pixel array, Changing means for changing the output signals of the pixels other than the pixel group by a predetermined amount.

Further, in the image pickup apparatus according to the present invention, the predetermined amount is not more than 1/60 of a maximum signal amplitude included in an image signal generated by the pixel array.

Further, in the image pickup apparatus according to the present invention, the pixel array includes a CMOS sensor.

Further, the image pickup apparatus according to the present invention further comprises an ID generating means for generating an ID of the image pickup apparatus, wherein the specific pixel group is a pixel group representing the ID. .

Further, in the imaging apparatus according to the present invention, the specific pixel group forms at least a character string representing the ID.

Further, in the imaging apparatus according to the present invention, the ID is a manufacturing number of the imaging apparatus.

Further, in the image pickup apparatus according to the present invention, the pixel array is formed on a sensor chip, and the sensor chip has an external input terminal.

Further, in the imaging apparatus according to the present invention, timer information and calendar information of a system for driving the sensor chip are input to the external input terminal.

Further, in the imaging apparatus according to the present invention, an ID of a system for driving the sensor chip is input to the external input terminal.

In the imaging apparatus according to the present invention, a name of a user of a system for driving the sensor chip is input to the external input terminal.

Further, in the imaging apparatus according to the present invention, it is characterized in that the external input terminal is supplied with position information at which a system for driving the sensor chip exists.

Further, in the imaging apparatus according to the present invention, the address information of the specific pixel group is input to the external input terminal.

Further, in the imaging apparatus according to the present invention, the specific pixel group includes a plurality of groups each including a plurality of non-overlapping pixels.

Further, in the image pickup apparatus according to the present invention, the specific pixel group includes pixels of a color which contributes most to a luminance component.

Further, in the image pickup apparatus according to the present invention, the specific pixel group extends over a plurality of adjacent pixels.

In the image pickup apparatus according to the present invention, the magnitude of the color difference signal obtained from the plurality of pixels is:
It is characterized in that it is set so as not to be different from the color difference signal of the pixel having no watermark.

In the imaging apparatus according to the present invention, an A / D converter for converting an output of the imaging apparatus into a digital signal.
It has a D conversion means, and the predetermined amount is a change of twice or more of the LSB of the A / D conversion means.

Further, in the image pickup apparatus according to the present invention, there is provided a signal processing means for processing an output signal of the image pickup apparatus, and the arrangement of the specific pixel group is not cut by a cut characteristic of a high frequency component in the signal processing means. It is characterized by having a spatial size.

Further, in the imaging apparatus according to the present invention, the signal processing means includes a compression means, and a cut characteristic of the high frequency component depends on a quantization step in the compression means.

[0033]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

(First Embodiment) FIG. 1 shows a monochrome CM having 640 × 480 pixels according to a first embodiment of the present invention.
FIG. 2 shows an equivalent circuit diagram of a pixel array section of an OS sensor type image sensor.

Reference numeral 11 denotes a pixel, which is 64 in a two-dimensional array.
0 × 480 are arranged. A photodiode 12 converts incident light into signal charges. Reference numeral 13a denotes an NMOSFET which is an amplification amplifier, which changes the amount of current flowing according to a voltage at which charges accumulated in the photodiode 12 are generated.

Numeral 14 denotes an NMOSFET for selecting a row,
A specific row can be selected by applying a voltage to the horizontal scanning line 17. Reference numeral 16 denotes a vertical signal line which is an output line of an optical signal, and is a signal line from which a current modulated by the optical signal charge flows.

The characteristic of the amplifier 13b of the central pixel 11 in FIG. 1 is different from the characteristic of the amplifier 13a of the other peripheral pixels 11. More specifically, since the gate length of MOSFET 13b is about 5% shorter than that of the periphery,
The current flowing through the ET 13b increases by about 5%. This central pixel 11 (11b) corresponds to a watermarked pixel.

In the present embodiment, there are 100 such watermark pixels at predetermined locations. This corresponds to 0.03% of the total number of pixels 307,200.

The above-mentioned 5% decrease in the current amount is relatively about 5%.
% Change in optical signal (watermark effect). But,
When the number of pixels is 0.03%, the decrease in relative image quality can be almost ignored.

The above-mentioned predetermined location differs for each image sensor. Combinations to choose 100 from the 307,200 pixels is ₃₀₇₂₀₀ C _100, the number of astronomical dimensions. Therefore, such 100 combinations can be used as unique IDs for distinguishing image sensors one by one. This ID can be a serial number for managing the order of manufacture.

A short MOS for forming the above watermark pixel
For example, in a gate lithography step of a semiconductor process for forming the imaging device, a gate electrode of an FET is scanned and drawn on a photoresist on a specific place using a laser drawing apparatus or the like, thereby shortening the gate length of the gate electrode. Can be formed.

The location of the 100 pixels can maintain its ID detection power even when some effects of the watermark pixels are weakened due to, for example, the type of image and the like and the pixels cannot be distinguished from others.

That is, the entire pixel is set to 3072 without overlapping.
If each is grouped into groups of 100, the number of possible IDs is 3072. Similar to classify the whole pixels in each 20 meter 15360, again the number of combinations when the in the selection of five groups from (i.e. a total of 100 watermarks) is ₁₅₃₆₀ C _5, which also It becomes a sufficiently large number and can be used as a serial number.

In this embodiment, the gate length of the MOSFET, which is an amplification amplifier, is used as the watermark element. However, the watermark element is not limited to this, and may be any parameter that affects the main characteristics of the imaging device. But it is good. As such a parameter, for example, the photodiode 1
2, light-shielding (opening) area, size, capacitance value, amplifier 1
3, gate area, gate width, gate capacitance, gate oxide film thickness, source / drain resistance, gate length, gate width, source / drain resistance of the selection MOSFET 14, ohmic contact with the vertical signal line 16, power supply voltage, etc. Is mentioned.

The watermarked image can specify the watermarked pixel later by known image processing.
That is, it is possible to specify the imaging device that has captured the image from the correspondence table between the predetermined pixel group and the unique ID.

(Second Embodiment) FIG. 2 shows a color CM of 1280 × 1024 pixels according to a second embodiment of the present invention.
3 shows a color filter array of an OS sensor type image sensor.

The arrangement shown is a known primary color Bayer arrangement.

When a watermark pixel is inserted for each pixel,
It is conceivable that the effect of the watermark on image compression is weakened and lost. This is because image compression is generally performed after spatial frequency expansion of image data by DCT or the like, for example, by sampling only low-order data in a quantization step. In image compression, the sampling frequency may differ between the luminance component and the color component,
Generally, the sampling frequency of the luminance signal ≧ the sampling frequency of the color signal.

Therefore, it is desirable to put the watermark in the color pixel which contributes the most to the luminance component. For this reason, in the present embodiment, a watermark pixel 22 having a different pixel opening area is set for a G (green) pixel 21G.

In the compression operation, when a plurality of adjacent pixels are set as watermark pixels, the watermark component remains in the low-frequency component, so that the resistance is improved.

At this time, if a watermark is applied only to a specific color as described above, it becomes more noticeable to human eyes. The human eye is generally more sensitive to color differences than luminance differences.

(Third Embodiment) FIG. 3 shows a complementary color filter array of a color CCD type image pickup apparatus according to a third embodiment of the present invention.

The watermark pixels are 3 × 3 = 9 pixels 32. In the watermark pixel 32 covering different colors, the area on which light enters is different from other pixels 31 and is increased by about 1.5%. The luminance signal obtained from the watermark pixel 32 is therefore increased by about 1.5%, and the color difference signals are kept substantially the same.

Since the human eye cannot perceive a continuous brightness difference of about 1.6%, the above watermark is not noticeable to the human eye. However, it is possible to sufficiently distinguish image data having a luminance range of 256 gradations of 8 bits.

In this embodiment, the size of the watermark pixel is 3 ×
Although it is set to 3, it is essential only that the size be large enough to withstand cutting of high frequency components in a compression operation or the like.

Further, the present invention is not limited to changing the light incident area to that of the other pixels. In short, any parameter may be used as long as it is not a color difference signal but a parameter that changes only a luminance signal. Such parameters include an accumulation time.

(Fourth Embodiment) FIG. 4 shows a monochrome CM having 1260 × 1024 pixels according to a fourth embodiment of the present invention.
FIG. 1 shows a system block diagram of an imaging device using an OS sensor type imaging device.

Reference numeral 41 denotes an optical system. Light incident on the CMOS sensor semiconductor chip 42
DS (correlation double sampling), PGA
(Programmable gain amplifier)
Output from the image output terminal 43. The output image data contains a watermark as described above.

This image is output to a system bus 47 via an A / D converter 45 and a DSP (digital signal processor) 46.

The bus 47 is controlled by the CPU 49 of the system, and the image data is stored in the memory 48 or the like.

The system of the imaging apparatus has a timer and a calendar function, and the date and time are recorded. This date and time can be output to the bus 47 of the system by giving an instruction to the CPU 49.

A converter 50 is connected to the bus 47 and can input the date and time information output to the bus 47 and the serial number which is its own manufacturing number to the external input terminal 44 of the sensor 42. I can do it.

FIG. 5 shows a system block diagram of the converter 50.

By pressing the shutter of the imaging device, the bus 4
The imaging date and time output to 7 is taken into the latch 53 at a predetermined timing by the control signal wiring 51 controlled by the CPU. The date and time signal captured by the latch 53 is converted by the character string conversion circuit 54 into an eight-character string representing the date and time of YYYY: MM: DD. 55 is a converter 50
ROM that stores the serial number of the device in the form of a character string
, And both character strings are synthesized, and ID + YYYY: M
The character string M: DD is output to the character string memory 56. The character string in the character string memory 56 is represented by the size of the pixel array of the sensor 42 in the form of a corresponding binary code.
It is developed in a two-dimensional memory 57 having a size of one bit.

This expansion is performed as follows.

The synthesized character string is, for example, 012319.
Assuming that the character string is 99 06 22, the ASCII code corresponding to this character string is 0 × 30, 31, 32, 33, 31,.
39, 30, 36, 32, 32, the pixel arrays (1, 0 × 30) (2, 0 × 31), (3, 0 × 3)
2)... Bit 1 is set at addresses (11, 0 × 32) and (12, 0 × 32).

The bit information in the memory 57 is stored in a control line 58
Are output to the external input terminal 44 in the order of access of the pixel array.

FIG. 6 shows an internal circuit diagram of the sensor 42.

Reference numeral 61 denotes a pixel array. The outputted optical signal of each pixel passes through a PGA circuit 65 and a CDS circuit 66.
The signal is input to one terminal of the adder 67. The bit information (watermark signal) in the memory 57 is input from the terminal 44 to the amplifier 68 in synchronization with the output of the optical signal of each pixel. The amplifier 68 converts the amplitude of the watermark signal having the digital signal amplitude into a voltage amplitude about twice as large as the LSB of the A / D converter 45, and outputs the voltage to the other terminal of the adder 67. As a result, in the pixel having the information of bit 1, the voltage of the optical signal increases by about twice the LSB (watermark state).
The watermarked signal is output from the output terminal 43 to the A / D converter 4.
5 is output.

According to the present embodiment, it is possible to record the unique number (ID) of the system and the date and time when the image was taken in the image data. The image sensor used in the present invention is not limited to the CMOS type, but may be another sensor, for example, a CCD type.

Further, the form of the date and time used in the present invention is not limited to the above embodiment, and it is possible to record, for example, up to hours, minutes and seconds. Also, the method of expanding the data may be any known method capable of performing an inverse transformation for obtaining original information from a watermark later.

The information input to the converter 50 is not limited to the date and time, but information having a binary code that can be converted into a character string, for example, the name of the user of the imaging apparatus, and information obtained by another GPS circuit. Location information may be used.

It is useful to specify the image of the user of the imaging apparatus, that is, the photographer, on the image to clearly and protect the copyright of the image.
In addition, the entry of the position information is very credible and useful in the legal handling of the image.

In the present embodiment, the converter 50 for forming the watermark signal is a separate chip from the sensor 42. However, it is also possible to incorporate a part or all of the functions of the converter 50 into the semiconductor sensor chip. It is.

[0075]

As described above, according to the present invention,
It is possible to realize an imaging apparatus that provides an image that can solve various problems that occur in handling of an image, for example, copyright, credibility as evidence, and the like.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a second embodiment of the present invention.

FIG. 3 is a diagram showing a third embodiment of the present invention.

FIG. 4 is a block diagram illustrating a configuration of an imaging device according to a fourth embodiment of the present invention.

FIG. 5 is a block diagram illustrating a configuration of a converter.

FIG. 6 is a block diagram showing an internal structure of the sensor.

[Description of Signs] 11 pixel 12 diode 13, 14, 15 MOSFET 16 vertical signal line 17 horizontal scanning line 18 horizontal reset line 21, 31 pixel 22, 32 watermark pixel 41 optical system 42 sensor 43, 44 terminal 45 A / D conversion Device 46 DSP 47 bus 48 memory 49 CPU 50 converter

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // H04N 101: 00 H04N 101: 00 F term (Reference) 5C022 AA13 AC31 AC42 5C024 AA01 BA01 CA00 CA27 DA01 DA04 DA07 FA01 FA12 GA01 GA31 GA51 HA14 HA25 5C065 AA03 BB48 CC01 CC03 CC08 CC09 DD15 DD17 EE05 EE07 GG18 GG30 GG31 GG32 5C076 AA14 BA06

Claims (19)

[Claims] 1. A pixel array in which a plurality of pixels for converting incident light into an electric signal are arranged, and an output signal of a specific pixel group of the pixel array is compared with an output signal of a pixel other than the specific pixel group. An image pickup apparatus comprising: a changing unit that changes a predetermined amount by a predetermined amount. 2. The imaging apparatus according to claim 1, wherein the predetermined amount is equal to or less than 1/60 of a maximum signal amplitude included in an image signal generated by the pixel array. 3. The imaging device according to claim 1, wherein the pixel array is formed of a CMOS sensor. 4. An image forming apparatus further comprising: an ID generating unit configured to generate an ID of the imaging device, wherein the specific pixel group is
The image pickup apparatus according to claim 1, wherein the pixel group represents a pixel group. 5. The specific pixel group includes at least the I
5. A character string representing D is formed.
An imaging device according to claim 1. 6. The imaging device according to claim 4, wherein the ID is a manufacturing number of the imaging device. 7. The imaging device according to claim 1, wherein the pixel array is formed on a sensor chip, and the sensor chip has an external input terminal. 8. The imaging apparatus according to claim 7, wherein timer information and calendar information of a system for driving the sensor chip are input to the external input terminal. 9. The imaging device according to claim 7, wherein an ID of a system for driving the sensor chip is input to the external input terminal. 10. The imaging device according to claim 7, wherein a name of a user of a system for driving the sensor chip is input to the external input terminal. 11. The imaging apparatus according to claim 7, wherein positional information on a system that drives the sensor chip is input to the external input terminal. 12. The address information of the specific pixel group is input to the external input terminal.
An imaging device according to claim 1. 13. The imaging apparatus according to claim 1, wherein the specific pixel group includes a plurality of groups each including a plurality of non-overlapping pixels. 14. The imaging apparatus according to claim 1, wherein the specific pixel group includes pixels of a color that contributes most to a luminance component. 15. The imaging apparatus according to claim 1, wherein the specific pixel group extends over a plurality of adjacent pixels. 16. The imaging method according to claim 15, wherein a magnitude of a color difference signal obtained from the plurality of pixels is set so as not to be different from a color difference signal of a pixel without watermark. apparatus. 17. An apparatus according to claim 17, further comprising A / D conversion means for converting an output of said imaging device into a digital signal, wherein said predetermined amount is at least twice as large as LSB of said A / D conversion means. The imaging device according to claim 1. 18. The image processing apparatus according to claim 18, further comprising: a signal processing unit configured to process an output signal of the imaging device, wherein the arrangement of the specific pixel group has a spatial size that is not cut by a cut characteristic of a high frequency component in the signal processing unit. The imaging device according to claim 1, wherein: 19. The signal processing means includes a compression means,
2. The imaging apparatus according to claim 1, wherein the cut characteristic of the high frequency component depends on a quantization step in the compression unit.