JP2662968B2 - Video printer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video printer for making a hard copy of a moving image such as a television image.

2. Description of the Related Art A video printer prints a display image on a screen as it is on paper, and can easily convert a television image into a hard copy like a photograph. In this type of printer, a video signal for one frame of an image to be printed is input, and the digital signal is taken into a frame memory.
If all of the image data stored in the frame memory is read out as it is and converted into a material image by two-dimensional scanning, the image of the first field and the image of the second field are combined, and one image by the double density printing process is obtained. You will get a hard copy of the top.

In the case of a still image, such printing processing may be performed. However, in the case of a moving image, there is a motion (blurring) in the image between the first field and the second field constituting the frame. If you print together, you'll end up with a blurry, low-quality hardcopy.

Therefore, for example, the first field is selected, the second field is discarded, a pseudo second field is created from the first field by interpolation, and a hard copy of one frame is created by printing these two fields. .
As an interpolation method, each pixel data of the first field is shifted by one horizontal scanning line to be pseudo-pixel data of the second field, or an average value of two upper and lower pixels of the first field or four left and right upper and lower pixels is pseudo. There is a method of using pixel data of the second field. In the former method, the image of the first field is printed twice as it is, and is also called a double writing method.

[Problems to be Solved by the Invention] By the way, even in a moving image, not all of the image is moving, and a moving pair (moving image area) of a person or a car and a stationary body such as a house or a tree in the background. (Still image area). However, conventionally, in the case of a moving image, since the interpolation is performed unconditionally for the entire image, there is a problem that the resolution is reduced in a still image area.

In Japanese Patent Application Laid-Open No. 62-207090 "Video Printer", a moving image is stored in a frame memory composed of a pair of field memories, and an output screen of one of the field memories is visually selected. Discloses an apparatus configured to interpolate between selected data to obtain a stamp image for one frame. However, this is a configuration in which a field image closer to a still image is visually selected and selected, and the selected data is subjected to intra-field interpolation to print.
Since the selection of a field image close to a still image is based on subjectivity, an objective selection standard cannot be established,
Intra-field interpolation is performed by generating interpolated data using correlation between data every other pixel in the horizontal direction or the vertical direction. Therefore, a moving image portion included in one image is good, but a portion close to a still image is good. However, there is a problem that the image quality is easily deteriorated.

Also, Japanese Patent Application Laid-Open No. 63-102576 published after filing the application of the present invention.
In the issue of "Video Printer", there is disclosed an apparatus which prints an image signal of one field for a moving image and prints an image signal of one frame for a still image.
However, this is a configuration in which a density difference between corresponding pixels between fields is obtained, the presence or absence of a change for each pixel is detected by an absolute value comparator, and a moving image and a still image are distinguished based on the total number of changed pixels. For this reason, while comparing the density difference for each small area, it is necessary to determine whether it is a moving image or a still image over the entire screen, and to perform still image processing or moving image processing on the entire screen, so that many still image areas are included. However, an image that is determined to be a moving image or an image that is determined to be a still image while including a large number of moving image areas has a problem that the resolution is inevitably degraded.

Similarly, Japanese Unexamined Patent Publication No.
No. 1549 "Video Printer" uses a single field memory, prints only one field of image data for moving images to prevent double images, and for still images, performs offset sampling between fields. An apparatus that prints data to improve image quality is disclosed. However, this method prints economically using a single field memory, and is therefore limited by the storage capacity of the field memory in terms of resolution, so that a printer that prints using two field memories is required. Was inferior. In addition, the luminance difference between the pixels adjacent to the upper and lower sides of the screen in one field and the other field of the interlaced scanning is detected, and the number of pixels in which the luminance difference is equal to or more than a predetermined value is counted. Is a moving image processing when it is a moving image.
After determining whether the entire frame image is a moving image or a still image, the image is fixed to one of the moving image processing and the still image processing and printed, so for example, the moving image may include a large number of still image areas, An image determined to be a still image or an image determined to be a still image while including a large number of moving image areas has a problem that further deterioration in resolution cannot be avoided.

Further, Japanese Patent Application Laid-Open No. 1-1148 published after filing the application of the present invention.
No. 3 `` Video Printer '' compares the amount of correlation between moving images reproduced one after another in chronological order in the previous and next frames and outputs it as an inter-frame correlation amount.This inter-frame correlation amount is compared with a preset setting amount. In comparison, when the inter-frame correlation amount is smaller than the set amount, it is determined that the scene is a transition, and when a certain time has elapsed thereafter or when the correlation amount has become equal to or more than a certain amount, the image signal of one frame is determined. An apparatus for taking out and printing is disclosed. However, this is a device that only takes out a frame at each scene change from a video movie and prints the image. When printing a scene that includes many moving image areas even at a scene change, degradation of resolution is inevitable. It had problems.

The present invention has been made in view of the above problems, and has as its object to provide a video printer which prints a moving image without causing a decrease in resolution of a still image area.

[Means for Solving the Problems] In order to achieve the above object, the present invention compares pixel data of one field of interlaced scanning with data of adjacent pixels of the other field, and compares the data of one field with the data of the other field. Motion detection means for detecting the motion of the image of each of the pixels, and for each pixel from the degree of motion to determine whether it is a moving image area or a still image area, receiving the determination result of the motion determination means, and vertically adjacent to the one field As pixel data for interpolating a pair of pixels, an average value of data of a plurality of pixels including the pair of pixels or surrounding pixels is selected in the case of a moving image region, and the other is selected in the case of a still image region. And selecting means for selecting data of pixels in the field and performing double density printing.

[Operation] According to the present invention, when an image is moving, the image does not match between one field and the other field, and a difference appears in pixel data of both fields, and this difference corresponds to the degree of movement. doing. Therefore, when this difference is larger than the reference value, it can be determined as a moving image area, and when smaller than that, it can be determined as a still image area. Based on such a motion determination result, as data of a pixel for interpolating a pair of vertically adjacent pixels of one field, a plurality of pixels including the pair of pixels or pixels in the vicinity thereof in the case of a moving image area. In addition to selecting the average value of the data, if it is a still image area, the pixel data of the other field is selected and subjected to double-density printing processing, so that a hard copy with good image quality can be obtained for both the stationary and moving parts. can get.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram showing a configuration of an important part of a video printer according to an embodiment of the present invention, FIG. 2 is a diagram showing an array of pixel data corresponding to pixels of an image, and FIG. FIG. 5 is a timing chart of data and signals of respective units for explaining the operation of FIG.

In this embodiment, the mode selection switch 32 allows the user to select any one of the four printing modes. “Motion” is a mode for printing a moving image in which a moving image region and a still image region are mixed. “Field I” and “Field II” are modes for printing a moving image in which the entire image is moving using the same interpolation method as before. The former uses the double writing method, and the latter uses the vertical interpolation method. Used. “Frame” is a mode for printing a still image. The switch 32 supplies a 2-bit mode selection signal MS corresponding to the selected mode to the determination circuit 34.

At the time of printing, pixel data of the first field and pixel data of the second field are alternately supplied to the input terminal 10 one by one from a frame memory (not shown). The pixel data is, for example, 8-bit data and has information on the color, luminance, and the like of the corresponding pixel. Latch circuit
12 to 20 are connected in cascade, and each latch circuit
Each time CLK is input, the pixel data received at the input terminal is latched.

Movement Determination Means The movement determination means of this embodiment includes latch circuits 12 to 16, an addition circuit 22, a subtraction circuit 24, a latch circuit 30, a determination circuit 34, and a latch circuit 36.

The addition circuit 22 inputs the pixel data from the latch circuit 12 and the pixel data from the latch circuit 16. These pixel data are two consecutive pixel data belonging to the same field. The adder circuit 22 adds the pixel data and calculates a value obtained by multiplying the sum by 1/2, that is, an average value of both pixel data, and supplies the average value to one input terminal of the subtraction circuit 24. The other input terminal of the subtraction circuit 24 is supplied with the pixel data from the latch circuit 14. This pixel data is pixel data of a different field (for example, the second field) sandwiched between two consecutive pixel data of the same field (for example, the first field) input to the addition circuit 22. The subtraction circuit 24 subtracts the pixel data from the output data of the addition circuit 22. The resulting subtraction value is the difference between the pixel data of the first field and the pixel data of the second field for a region of three consecutive pixels. The larger the motion of the image in this region, the larger the value. The smaller the motion of the image, the smaller the value.
The subtraction value is used as the motion detection data MV indicating the motion of the image for the small area of three pixels,
The signal is once latched by 30 and is supplied to the determination circuit 34 from there.

In the “motion” mode, the determination circuit 34 compares the motion detection data MV from the latch circuit 30 with a reference value,
When the former is smaller than the latter, it outputs a motion determination signal DE such that it becomes "1", and when the former is smaller, it becomes "0". That is, for a small area composed of three pixels corresponding to the three pixel data latched by the latch circuits 12 to 16, when the motion of the image is smaller than the reference value, the still image area having no motion or a small motion is determined. Is determined (DE = “1”), and when the motion of the image exceeds the reference value, it is determined that the area is a moving image area (DE = “1”).
“0”). The judgment circuit 34 outputs a judgment output DE for each clock CLK.
, But alternately with a constant signal “1”.

The determination circuit 34 outputs a constant signal regardless of the motion detection data in other modes. That is, in the “frame” mode, a constant signal “1” is continuously output. In the “field I” mode, a constant signal “1” is continuously output. In the “field II” mode, constant signals “1” and “0” are output alternately.

The output signal of the determination circuit 34 is temporarily latched by the latch circuit 36, and is supplied to the selector circuit 28 as a switching control signal.

Selector The selector of this embodiment includes latch circuits 16 to 20, an adder circuit 26, and a selector circuit 28.

The addition circuit 26 inputs the pixel data from the latch circuit 16 and the pixel data from the latch circuit 20. These pixel data are two consecutive pixel data belonging to the same field. The addition circuit 26 adds the pixel data and calculates a value obtained by multiplying the sum by 1/2, that is, an average value of both pixel data, and supplies the average value to one input terminal α of the selector circuit 28. . This average value is used as pixel data for interpolation. Pixel data from the latch circuit 18 is supplied to the other input terminal β of the selector circuit 28.

The selector circuit 28 responds to the switching control signal from the above-described motion judging means to select one of the two inputs α and β and outputs it to the latch circuit 38. An output terminal of the latch circuit 38 is connected to an input terminal of a subsequent process circuit (not shown) via a terminal 40, and an output terminal of the process circuit is connected to a print head.

As described above, in the “motion” mode, the switching control signal is such that the motion determination signal DE and the constant signal “1” appear alternately. Therefore, when a fixed signal "1" is given, the input β, that is, the pixel data from the latch circuit 18, is unconditionally selected. However, the next clock CL
When the motion determination signal DE is given by K, when it is “0” (in the moving image area), the input α, that is, the interpolation data from the adding circuit 26 is selected, and when it is “1” (still image In the case of a region, the input β (pixel data from the latch circuit 18) is selected. In this case, when the interpolation data is selected, the printing process for the moving image is performed by using the interpolation data as the printing data. When the pixel data from the latch circuit 18 is selected without selecting the interpolation data, printing processing for a still image is performed.

Operation Next, the operation of this embodiment will be described with reference to FIGS. FIG. 2 shows an arrangement state of pixel data corresponding to pixels of an image. The first according to the interlace method
The pixel data of the field and the pixel data of the second field are alternately arranged in the vertical direction. By reading out one line at a time from the frame memory in the vertical direction, A, a, B, b,
C, c}, the pixel data of the first field and the pixel data of the second field are sent alternately one by one.

FIG. 3 is a timing chart of data and signals of each section in FIG. Each time the clock CLK rises, each pixel data A, a, B, b} is transferred to the next-stage latch circuit. Thus, when the pixel data A and B of the first field are latched by the latch circuits 16 and 12 and the pixel data a of the second field are latched by the latch circuit 14 at the rising of the third clock CLK3, The average value (A + B) / 2 of A and B is obtained from the adder circuit 22, and the subtracted value (A +
B) / 2-a is obtained. At the next clock CLK4, the subtraction value is latched by the latch circuit 30, and is input to the determination circuit 34 as motion detection data MV.

The motion detection data MV indicates a degree of motion of an image in a small area including three pixels corresponding to three pieces of pixel data A, a, and B. In the “motion” mode, if the MV value is smaller than the reference value, the logic level becomes “1” indicating the determination as a still image area. If the MV value is equal to or exceeds the reference value, the moving image is displayed. The determination circuit 34 obtains a motion determination signal DE having a logical level of “0” indicating the determination of the area. This signal DE is latched by the latch circuit 36 at the next rise of the clock CLK5.

On the other hand, at the rise of the clock CLK5, the pixel data A and B of the first field are latched by the latch circuits 20 and 16, respectively.
The average value (A + B) / 2 is given from the adder circuit 26 to the input terminal α of the selector circuit 28 as interpolation data. Further, the pixel data a of the second field is latched by the latch circuit 18 and applied to the input terminal β of the selector circuit 28. Therefore, when DE = "1", the pixel data a of the second field is selected and the printing processing for a still image is performed. When DE = "0", the interpolation data (A + B) / 2 is selected and the moving image processing for a moving image is selected. Is performed on the small area (A, a, B).

Thus, in the “motion” mode, two consecutive pixels in the first field and the second pixel
For each small area of three pixels consisting of one pixel in the field, according to the motion determination result, whether there is no motion,
Even if there is, the still image processing is performed when the movement is smaller than the reference, and the moving image processing is performed when the movement is larger than the reference. Therefore, one frame of a moving image in which both the image quality of the moving image region and the image quality of the still image region are excellent is printed.

As described above, according to the video printer, the first field and the second field are overlapped on the screen in the vertical direction when the first field and the second field are overlapped on the screen as the respective small areas of the moving image in which the moving body and the stationary body are mixed. Attention is paid to determining whether each pixel is a moving image area or a still image area based on the correlation between the data of these pixels, that is, the presence or absence of motion of the image in the second field with reference to the first field, and based on the determination result. In the case of a moving image area, the printing processing for a moving image is performed, and in the case of a still image area, the printing processing for a still image is performed. Accordingly, it is possible to perform printing with the image quality of a moving image corrected without lowering the resolution of the stationary body portion. Therefore, determination of whether the image is a moving image or a still image is performed on the entire screen, and still image processing or moving image processing is performed on the entire screen. As in the conventional device, the image determined to be a still image while including a large number of still image regions and a moving image and a moving image region is determined, as a result of uniformly following the same print processing over the entire screen, Deterioration in resolution is not unavoidable, and a single image can be satisfactorily printed by an optimal interpolation method for each small area.

FIG. 2K shows the output of the latch circuit 38 in the "frame" mode. In this case, the determination circuit 34 outputs a "1" switching control signal in accordance with a predetermined value of the mode switching signal MS from the mode switching switch 32. Accordingly, the selector circuit 28 selects only the pixel data from the latch circuit 18, so that the pixel data of the first field and the pixel data of the second field are alternately selected one by one as the print data. Thus, the still image processing is performed.

FIG. 2 (L) shows the case of the "field I" mode. In this case as well, the judgment circuit 34 outputs only the switching control signal of "1", but the clock CLK is supplied to the latch circuit 38 at a rate of one in two cycles. As a result, the pixel data (A, B, C, の) of the first field is supplied from the latch circuit 38 to the second clock CLK.
It is output sequentially for each cycle. As a result, the second field is completely replaced with the first field, and the moving image processing by the twice-writing interpolation method is performed.

FIG. 2M shows the case of the “field II” mode. In this case, “1”, “0” at each rising edge of the clock CLK
Selector circuit according to the switching control signal which alternates
28 alternately switches the inputs β and α, so that the pixel data (A, B, C, ‥) and the interpolation data ((A
+ B) / 2, (B + C) / 2, (C + D) / 2, ‥) are output alternately. As a result, each pixel data in the second field is replaced with interpolation data, that is, the average value of the pixel data in the upper and lower first fields, and the moving image processing by the vertical interpolation method is performed.

In this embodiment, the second field is interpolated on the basis of the first field. However, the relationship between the two fields can be reversed. Further, the data interpolation is not limited to the average value of the upper and lower two pixels in the first field, but can be performed using the average value of the left, right, upper and lower four pixels.

[Effects of the Invention] As described above, according to the present invention, pixel data of one field of interlaced scanning is compared with data of adjacent pixels of the other field, and the image of the other field is compared with the data of one field. Motion is detected, a moving image area or a still image area is determined for each pixel from the degree of the motion, and as pixel data for interpolating a pair of vertically adjacent pixels in one field, if the moving image area, the pair of pixels is used. Since the average value of the data of a plurality of pixels including the pixel or its surrounding pixels is selected, and in the case of a still image area, the data of the pixel of the other field is selected and subjected to the double density printing process, Focusing on the vertical adjacent pixels when one field and the other field are overlapped on the screen as each small area of the moving image in which the moving body and the stationary body are mixed, Based on the correlation between the data of these pixels, i.e., the presence or absence of motion of the image in the even field with reference to one field, it is determined whether each pixel is a moving image area or a still image area. If it is, the optimal print processing can be selected for each small area, such as performing the print processing for moving images, and performing the print processing for still images in the still image area. It is possible to print with the image quality of the video corrected without reducing the image quality.
As in the conventional apparatus that performs still image processing or moving image processing on the entire screen, an image that is determined to be a moving image while including a large number of still image areas or an image that is determined to be a still image while including a large number of moving image areas is displayed on the entire screen. As a result of following the same print processing uniformly, there is no inevitable deterioration in resolution, and excellent effects such as good print processing of one image by the optimal interpolation method for each small area. To play.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of an important part of a video printer according to an embodiment of the present invention, FIG. 2 is a diagram showing an array of pixel data corresponding to pixels of an image, and FIG. FIG. 5 is a timing chart of data and signals of respective units for explaining the operation of FIG. In the drawing, 12 to 20: Latch circuit 22, 26: Addition circuit 24: Subtraction circuit 28: Selector circuit 30, 36, 38 ... Latch circuit 32: Mode switch 34: Judgment circuit

Claims (1)

(57) [Claims] An interlaced scan compares pixel data of one field with data of adjacent pixels of the other field, detects the motion of the image of the other field with respect to one field, and determines the motion of each pixel from the degree of motion. A motion determining unit that determines whether the image is a moving image region or a still image region; and a determination result of the motion determining unit. For example, the average value of the data of a plurality of pixels including the pair of pixels or its surrounding pixels is selected, and in the case of a still image area, the data of the pixels of the other field is selected and subjected to double density printing processing. A video printer, comprising: selecting means.