JPH1084555A - Image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a processing time for an entire system from increasing by adding a dither signal to an image signal, quantizing the sum, coding and storing the quantized image signal. SOLUTION: When an object image is formed on an image pickup face of a CCD 102 being an image pickup means through a lens 101, the object image formed on the face of the CCD 102 is separated into each color component by a color separation filter provided onto the face of the CCD 102 and given to an A/D converter 103, in which the component is converted into digital data in each color. The digital data are converted into specific image data by an image forming processing section 104 and recorded on a recording medium 106. In the case of the print pickup mode, since a switch 100 is thrown to the position (b), RGB image data generated by the image forming processing section 104 are given to a color conversion processing section 107, in which the data are converted into color data used by an ink jet printer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an imaging apparatus for digitally processing captured image data.

[0002]

2. Description of the Related Art In recent years, image data is often handled on personal computers with the advancement of personal computers and the development of desktop publishing (DTP).
In such a situation, 1
As one method, a digital camera is attracting attention. Further, there is a color printer which prints out image data taken into a personal computer. However, this color printer has been widely used due to a reduction in price, and the taken image is often output in color.

In order to print out an image captured by such a digital camera with a printer, the digital camera and the printer are connected to a personal computer, and image data is taken from the digital camera into the personal computer and output to the printer according to instructions from the personal computer. After performing signal processing suitable for the above, the image is output to a printer. Digital camera to JP
When image data compressed by EG is taken into a personal computer, JPEG compression must be decompressed on the personal computer, and color conversion processing into CMYK data for output to a printer and binarization processing are also performed on the personal computer. Was going on.

[0004]

As described above, in the conventional system, since the decompression of JPEG compression, color conversion processing, binarization processing, etc. are all performed on a personal computer, a great deal of time is required for signal processing. Was. Currently, 10
There are not many digital cameras that handle more than 100,000 pixels, but it is necessary to increase the number of pixels to handle in order to achieve photo quality. Also, in a printer, when high-density recording is performed to improve image quality, image data to be input to the printer necessarily increases, so that there is a problem that the processing time of the entire system further increases.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and an image pickup apparatus according to claim 1, wherein an image pickup means for picking up a subject image and outputting an image signal; A / D conversion means for digitizing an image signal output from an imaging means, addition means for adding a dither signal to the image signal digitized by the A / D conversion means, and addition of a dither signal by the addition means Quantization means for quantizing the image signal, encoding means for encoding the image signal quantized by the quantization means, and storage means for storing the image signal encoded by the encoding means. , Is characterized by having.

[0006]

Embodiments of the present invention will be described below with reference to the drawings.

<First Embodiment> FIG. 1 is a block diagram showing a configuration of a digital camera which is an image pickup apparatus according to a first embodiment. The operation of the entire camera is controlled by a control unit (not shown), and can switch between a normal shooting mode and a print shooting mode. First, the normal shooting mode will be described. The subject image is captured by the lens
When an image is formed on the image pickup surface of the CD 102, the subject image formed on the CCD surface is separated into each color component by a color separation filter provided on the CCD surface, and A / D conversion means A / D conversion means is used. The data is converted into digital data of each color by the D converter 103. These digital data are converted by the image forming processing unit 104 into RGB 24-bit / pixel image data. Further, in the normal photographing mode, since the switch 100 as the mode switching means is switched to the a side, the output of the image forming processing unit 104 is input to the JPEG encoder 105, and the image is converted into the JPEG format which is the international standard for still image encoding. The data is converted and written on the recording medium 106 as recording means.

Next, the print photographing mode will be described. The flow of signals from the lens 101 to the image forming processing unit 104 is the same as that in the above-described normal photographing mode, and the description is omitted. In the print shooting mode, since the switch 100 is switched to the b side, the RGB image data created by the image forming processing unit 104 is input to the color conversion processing unit 107, which is a color conversion unit, and used by the inkjet printer. Is converted to 32 bit / pixel CMYK color data.

The color conversion processing unit 107 performs color conversion by a look-up table method.
Grid points of 33 levels for each B color, that is, 33 × 33 × 33
24bit RGB signal is converted to 32bi using the table
is converted to a CMYK signal of t. Data other than the lattice points can be obtained by performing linear interpolation from the CMYK data of the lattice points surrounding the data. Note that the linear interpolation used here is one example, and other interpolation methods may be used. Further, in the present embodiment, a color conversion table having a capacity of about 140 Kbytes is used in order to accurately perform color conversion. However, when the memory capacity is limited,
The conversion may be performed using a 17 × 17 × 17 table (about 20 Kbytes).

Next, the converted CMYK image data is supplied to a scalar quantization unit 108 serving as an addition unit and a quantization unit.
And is scalar quantized. Here, quantization is performed in consideration of the characteristics of the printer so as not to greatly affect the image quality at the time of printout. Hereinafter, this quantization method will be described.

Here, a case where a binary recording type ink jet printer is used as a printer will be described. In general, an ink jet printer forms an image by binary recording of whether or not dots are formed, and expresses a gradation by the number of dots formed in a certain area. For example, if one pixel is formed by 4 × 4 dots, gradations from 0 to 16 can be expressed. In this case, the input image data has 8 bits, that is, 256 levels of data. However, the printer can express only 17 levels of gradation from 0 to 16. If data quantization is performed by using the data redundancy generated here, the image quality to be printed out is hardly affected.

FIG. 2 is a conceptual diagram showing this quantization. The image data 301 having 256 gradations of 8 bits / pixel is converted to 0, 16, 32, 48, 64,.
When quantizing using a threshold value of
Quantizing 6 as 1 level, 32 as 2 levels, etc., results in image data 302. However, if the image data 303 having a larger number of gradations is quantized, it becomes image data 304 and becomes exactly the same as the image data 302, and information between quantization level values cannot be expressed at all. Therefore, in the present embodiment, a pseudo halftone is expressed by adding a dither signal 305 to image data before quantization to scalar quantize each of CMYK 256-level signal values into 17-level signals. I am trying to do it.

[0013] The quantized image data is further encoded. The scalar-quantized image data is divided into 2 × 2 pixels, which are units encoded by the packing process. Then, the maximum value and the minimum value of 2 × 2 pixels, that is, four pixels are obtained. If the maximum value and the minimum value are equal to or larger than N, the vector encoding unit 111 as the encoding unit performs vector encoding as an edge portion, If it is smaller, the addition encoding unit 110, which is an encoding unit, performs addition encoding using Expression (1) as a flat part. (Here, N is a natural number from 0 to 15.)

A = M ₁₁ + M ₁₂ + M ₂₁ + M ₂₂ (1)

That is, 65 code values from 0 to 64 are assigned to the addition code. If it is recognized as an edge portion, an average value (Ave) of 2 × 2 pixels is obtained,
The average value and the value of 2 × 2 pixels are compared. If the average value is larger than the average value, the maximum value is replaced. That is, encoding is performed using three pieces of information of the maximum value (Max), the minimum value (Min), and the information of the arrangement (Arr) of the maximum value obtained by Expression (2).

[0016] _{if (M 11> Aυe) thenD} 11 = 1elseD 11 = 0 if (M 12> Aυe) thenD 12 = 1elseD 12 = 0 if (M 21> Aυe) thenD 21 = 1elseD 21 = 0 if (M 22> ^{_{Aυe) thenD 22 = 1elseD 22 =}} 0 S = D 3 11 + D 2 12 + D 1 21 + D 22 (2)

For example, the maximum value (Max) and the minimum value (Mi)
n) and 4 bits, that is, 12
If bit vector encoding is performed, encoding can be performed without deteriorating the signal. Also, by reducing the number of states of the maximum value and the minimum value, the number of codes assigned to the vector code can be reduced, and the compression ratio can be increased.

A = f (Max; Min, Arr) (3)

In this embodiment, a look-up table is used for the conversion of the equation (3), and the number of states of Min is reduced for the vector coding.
3, 958 codes were assigned. 10b for each 2 × 2 pixel for each color of CMYK by addition code and vector code
it encoded signal (CMYK10bit / pix
el) is written to the recording medium 106 as an image data format in the print mode.

FIG. 3 is a block diagram showing the configuration of the ink jet printer. When the print mode image data recorded on the recording medium of the digital camera is transferred to the printer, the decoding processing unit 201 decodes the image data encoded every 2 × 2 pixels. Here, the decoding process is performed separately into two of the addition code and the vector code. Since the addition code is composed of 2 × 2 pixels (one pixel is 4 × 4 dots), the density pattern processing unit 202
Can be developed by a density pattern method using a dither matrix composed of 8 × 8 dots having a threshold value of 1 to 64. The vector-encoded code is also decoded by the decoding processing unit 201, and the density pattern processing unit 202 outputs a 4 × 4 code having a threshold of 1 to 16.
A 2 × 2 pixel, that is, 4 pixels are developed by using a density pattern method based on a dither matrix composed of 4 dots, so that a binary representation is obtained.

As described above, the data of the addition code and the vector code are decoded in the decoding processing unit 201, and the data binarized by the density pattern method in the density pattern processing unit 202 is sent to the printer engine 203 and printed out. You.

In the case where the digital camera and the ink jet printer are configured as described above, the digital camera and the ink jet printer can directly connect the digital camera and the ink jet printer to print out the shot image by photographing the image in the print mode. It can be carried out. Furthermore, since a dither signal is added when quantizing a photographed image, it is possible to express pseudo gradation.

In this embodiment, one pixel is 4 × 4
Although the example of expressing the 17-level gradation by binarizing by using dots has been described, it is needless to say that one pixel is constituted by N × M dots and the N × M + 1-level gradation is expressed. It is also conceivable to perform encoding as much as possible. In the printer mode, a 10-bit code is assigned to each 2 × 2 pixel of each CMYK color. However, any number of codes such as 8, 9 bits may be assigned according to the memory of the system. By assigning codes in this manner, the compression ratio of image data, which was about 1/3 in the present embodiment, can be reduced to a compression ratio of 1/10, 1/20, or the like.

In this embodiment, the color conversion processing and the scalar quantization processing are performed as separate processing. However, these processings can be collectively converted by the color conversion processing unit 107 using an LUT. It is. By using this method, the capacity of the LUT can be further reduced.

<< Second Embodiment >> In the above-described first embodiment, the operation of each of the digital camera and the ink jet printer has been described.
A case where a digital camera and a printer are connected via a personal computer as shown in FIG.

First, printout of an image photographed in the general photographing mode of the digital camera will be described. In order to print out an image photographed in the normal photographing mode, it is necessary to connect a digital camera and a printer via a personal computer as shown in FIG. In such a connection, the printer driver is installed on the personal computer, so that the process of converting the data into data for printout can be performed on the personal computer. That is, image data taken by a digital camera is taken from the camera to a personal computer in the JPEG format,
JPEG decompression, color conversion, and binarization are performed by a printer driver installed in a personal computer, and the processed image data is transferred to a printer, thereby performing printout.

Next, printout of an image photographed in a print photographing mode by a digital camera will be described. Image data shot in print shooting mode
There is no need to perform processes such as color conversion and binarization with the driver of the inkjet printer installed in the personal computer, and the driver need only transfer the data to the printer.

Here, a case in which an image is previewed using the screen of a personal computer will be described. FIG. 5 and FIG.
FIG. 9 is an explanatory diagram of a preview process on a personal computer. The image data encoded in the printer mode is transmitted to the decoding processing unit 5.
01 and decrypted. The decoding process is shown in FIG.
Is the same as the decoding processing unit 201.

The image data in the printer mode is composed of a 2 × 2 pixel addition code signal 601 and a vector code signal 606 as shown in FIG. Is assigned to
These values are quadrupled by a 2-bit shift of the bit shift operation, and a pseudo-gradation processing unit 502 adds a dither signal 604 having a value from 0 to 3 to represent a pseudo-gradation. Then, image data 605 is obtained. On the other hand, the vector coded signal 606 is decoded to obtain image data 607, which is multiplied by 16 by a 4-bit shift of a bit shift operation to obtain image data 608. Further, a dither signal 609 having a value from 0 to 15 is added to express a pseudo gradation, and the image data 61 is displayed.
0 is obtained. Thus, each of C, M, Y and K is 2
After being converted to a signal with 56 levels,
The signal is converted to a B signal and output to the monitor 503.

As described above, the user can check the image while viewing the preview image displayed on the display of the monitor 503, and then print out the image. In the present embodiment, the preview of the print mode data is performed using the display of the personal computer. However, if the digital camera has a display, the preview may be performed using the display. It is possible.

Next, the case where the digital camera and the ink jet printer are directly connected will be briefly described. When a digital camera and an inkjet printer are connected using a cable, a recognition signal is first sent from the camera to the printer. When the printer is recognized, the printer stands by in a data receivable state. Next, an image to be output is selected on the digital camera side, and an instruction for printing and image data captured in the printer mode are transferred to the inkjet printer. The inkjet printer receives the transmitted data, performs decoding and binarization processing, and prints out the data.

With the above-described configuration, the processing for outputting the image photographed by the digital camera on the personal computer to the printer can be omitted, so that the processing time can be greatly reduced. Further, since the data for printout is recorded on the recording medium of the camera in a printable form, the digital camera and the printer can be directly connected and printed out easily.

[0033]

As described above, the image pickup means for picking up a subject image and outputting an image signal, the A / D conversion means for digitizing the image signal output from the image pickup means, and the A / D conversion means Adding means for adding a dither signal to the image signal digitized by the means, quantizing means for quantizing the image signal to which the dither signal has been added by the adding means, and image signal quantized by the quantizing means , And storage means for storing the image signal encoded by the encoding means, so that the A / D-converted image signal is quantized and encoded. In such a case, the gray scale can be expressed in a pseudo manner.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram of a digital camera according to an embodiment.

FIG. 2 is an explanatory diagram of quantization for pseudo gradation expression in the embodiment.

FIG. 3 is a configuration block diagram of a printer according to the embodiment.

FIG. 4 is a system configuration diagram in the embodiment.

FIG. 5 is a block diagram of a preview process according to the embodiment;

FIG. 6 is a diagram illustrating a data flow of a preview process according to the embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 switch 101 lens 102 CCD 103 A / D converter 104 image forming processing unit 105 JPEG encoder 106 recording medium 107 color conversion processing unit 108 scalar quantization unit 109 coding processing unit 110 addition coding unit 111 vector coding unit

Claims (6)

[Claims] An imaging unit that captures a subject image and outputs an image signal; an A / D conversion unit that digitizes an image signal output from the imaging unit; and an A / D conversion unit that is digitized by the A / D conversion unit. Adding means for adding a dither signal to the image signal; quantizing means for quantizing the image signal to which the dither signal has been added by the adding means; and encoding for coding the image signal quantized by the quantizing means. An imaging apparatus comprising: means for storing an image signal encoded by the encoding means. 2. The method according to claim 1, wherein the encoding unit includes:
An imaging apparatus that performs an encoding process according to the characteristics of a printer. 3. The imaging apparatus according to claim 1, wherein the image signal output from the imaging unit is a color signal, and further comprising a color conversion unit that performs color conversion on the image signal. 4. An imaging apparatus according to claim 3, wherein said adding means adds a dither signal to the image signal color-converted by said color converting means. 5. An imaging apparatus according to claim 3, wherein said color conversion means converts an RGB signal into a CMYK signal. 6. The apparatus according to claim 1, further comprising a mode switching means for switching between a first mode for outputting the image signal to a printer and a second mode for performing encoding in a method different from the first mode. An imaging device characterized by the above-mentioned.