JP3156247B2 - Image conversion device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image conversion apparatus for converting a moving image signal such as a television signal into a still image signal such as a signal for printer output.

2. Description of the Related Art Conventionally, there has been a request to print or print a specific instantaneous video of a television image as a still image.
The amount of information in the frame was small, that is, the image was coarse when viewed as a still image, and the opportunity for use was small.

However, in recent years, a high-definition television signal, so-called Hi-Vision, has been proposed, which has five times or more the amount of information as in the past, so that it can withstand viewing sufficiently when viewed as a still image. Further, with the progress of computer technology, applications for outputting a processed image of a computer as a still image to a printer have been widespread.

Therefore, a moving image / still image conversion device that outputs a video of a designated field or frame of a moving image signal as a still image has been commercialized. Conventional television systems, including high-definition television systems, employ an interlaced system, in which one frame image is formed by two field images formed by interlaced scanning in 1/60 second units. ing. Therefore, there is a 1/60 second time lag between the fields, and when the subject is moving, a still image of the desired quality can be obtained by simply combining two adjacent field images. I can't.

Therefore, a conversion device that obtains a moving amount and a fragrance of a moving object between fields by a motion vector detection method represented by a matching method or a density gradient method, corrects an image based on the obtained amount, and forms a clear still image without displacement. Was proposed.

[Problems to be Solved by the Invention] A technique for detecting a motion of an image and performing an interpolation process of the image by a method based on the detected motion has been already known. However, in the conventional method, since the quality of the image displayed on the monitor is considered, there is still room for improvement in the quality of the image for printing.

In view of the above, an object of the present invention is to provide an image conversion apparatus that improves the quality of a print image.

[Means for Solving the Problems] An image conversion apparatus according to the present invention includes: an image memory capable of storing image signals of a plurality of fields; an enlarging means for enlarging the image signals of the plurality of fields stored in the image memory; A detecting means for detecting a motion vector from the image signals of the plurality of fields enlarged by the enlarging means, and a motion for judging a motion amount based on the detection result of the detecting means based on characteristics of the printer and determining an interpolating means to be selected It is characterized in that it comprises an amount determining means and a color converting means for performing color conversion for printing on the image signals of the plurality of fields interpolated by the interpolating means.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration block diagram of an embodiment of the present invention,
FIG. 2 is a schematic block diagram showing a configuration in which a still image is obtained from a moving image source and output by a printer. 10 is a TV camera,
Reference numeral 12 denotes a video tape reproducing device, and reference numeral 14 denotes a television receiver. A moving image signal obtained from these devices is input to a moving image / still image converter 16 to form an enlarged still image signal for printer output. . The output of the video / still image converter 16 is applied to a color printer 18 and printed on paper.

The moving image / still image converter 16 basically includes a frame memory 19 for storing an image signal of an arbitrary frame among the moving image signals from the TV camera 10, the video reproducing device 12, or the television receiver 14, and a frame memory 19. An enlargement processing circuit 20 for enlarging the image signal stored in the memory 19 for printer output, and detecting a motion vector from the odd-field and even-field image signals of the image signal enlarged by the enlargement processing circuit 20,
A motion vector detection and interpolation circuit 22 for performing interpolation according to the detection result, and a color printer
And a color conversion circuit 24 for color conversion for 18. In this embodiment, the color conversion circuit 24, YP _R P _B (brightness color difference) signals YMC
Convert to Bk signal.

That is, in the present embodiment, the TV camera 10 and the video playback device 12
Alternatively, an image signal of an arbitrary frame among the moving image signals from the television receiver 14 is first taken into the frame memory 19, and then enlarged to a predetermined size by the enlargement processing circuit 20. The image signal enlarged by the enlargement processing circuit 20 is
Although it is stored in a frame memory (not shown) in the enlargement processing circuit 20, it may be stored in the frame memory 19 as a matter of course. The motion detection correction circuit 22 calculates the
A motion vector is detected, and the result is corrected by the selected correction method. Then, the color conversion circuit 24 converts the color of the image signal corrected by the motion detection correction circuit 22 into a color signal suitable for the printer 18 and outputs the color signal.

FIG. 2 is a block diagram showing a more detailed circuit configuration of the moving image / still image converter 16. The memories 30, 32, and 34 are for odd fields, and the memories 36, 38, and 40 are for even fields, and store image signals after being enlarged by the enlargement processing circuit 20, respectively. Specifically, the luminance signal Y is stored in the memories 30 and 36, the color difference signal P _R is stored in the memories 32 and 38, and the color difference signal P _B is stored in the memories 34 and 40.
Is stored. Reference numeral 42 denotes a motion vector detecting circuit for detecting a motion vector from the data stored in the memories 30 and 36 of the luminance signals of the field and the even field by the above-mentioned known method. Then, a signal indicating in which direction and how much the corresponding pixel in the other (odd field) has moved is output.

Reference numeral 44 denotes a motion amount determination circuit that determines a motion amount based on a detection result of the motion vector detection circuit 42 and determines an interpolation method to be selected. Usually, the motion amount is compared with a predetermined value, and an interpolation method is selected based on the comparison result.

Reference numerals 46, 48, and 50 denote interpolation circuits for executing interpolation by different interpolation methods on the data stored in the frame memory 20.
For example, the interpolation circuit 46 is an inter-field interpolation circuit, and is suitable when the amount of motion is small. The interpolation circuit 50 is an intra-field interpolation circuit, and is suitable for a case where the motion is large. The interpolation circuit 48 performs interpolation according to the medium movement.

The interpolation by the interpolation circuit 46 will be described with reference to FIG. The motion amount determination circuit 44 selects the interpolation circuit 46 when the motion amount between the two compared fields is zero or hardly perceived. As shown in FIG. 3, the interpolating circuit 46 performs inter-field interpolation in which even-field signals and odd-field signals are alternately arranged for each line.

FIG. 4 shows how interpolation is performed by the interpolation circuit 48. When the amount of motion between the compared fields is between a level that is almost recognized and a level that is slightly larger than the motion vector detection error limit, the motion amount determination circuit 44 selects the interpolation circuit 48. In this case, as shown in FIG. 4, the data of the odd field is returned to the position before the movement (that is, the corresponding position in the even field) in accordance with the detected motion vector, and the data is interpolated with the storage data of the even field. (Average value interpolation, etc.).

FIG. 5 shows how interpolation is performed by the interpolation circuit 50. When the motion amount between the compared fields is larger than the motion vector detection error limit, the motion amount determination circuit 44 selects the interpolation circuit 50. This is, for example, the case where image deletion occurs, and it is difficult to recognize the object shape itself. The interpolation circuit 50 forms data corresponding to a line of an odd field from pixel data above and below (or other adjacent pixels) by intra-field interpolation.

The threshold value for the selection of the interpolation circuits 46, 48, 50 is determined statistically in consideration of the perceptual limit of the interpolation error based on the human visual characteristics of the hard copy. Therefore, it is needless to say that the characteristics of the printer 18 are affected. This also corresponds to “evaluating the detected motion vector based on the characteristics of the printer” of the present invention.

In the above description, three interpolation methods are selected. However, two or four or more interpolation methods may be used. Further, different hardware constituted by the interpolators 46, 48, and 50 may be used, or one data processing device may be switched and operated by software.

Although the two field pictures to be compared have been described using the field closest in time, the comparison may be made between arbitrary fields, and the present invention is not limited to the combination of the odd field and the even field.

Further, as the input signal may be such as RGB signals other than YP _R P _B signal is not limited to the signal after conversion is also YMCBk signal.
Although the case of enlargement has been described as an example, the same can be applied to the case of reduction.

[Effects of the Invention] As can be easily understood from the above description, according to the present invention, a motion vector detected from an image signal of a plurality of enlarged fields is evaluated according to a parameter based on a characteristic of a printer. Since the image signals of a plurality of fields are interpolated by the method according to the evaluation result and the color conversion for printing is performed, it is possible to improve the quality of the image to be printed as compared with the related art.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention, FIG. 2 is an example of a circuit configuration of a moving image / still image converter 16, FIG. 3 is an explanatory diagram of interpolation by an interpolation circuit 46 of FIG. The figure shows the interpolation circuit 48
FIG. 5 is an explanatory diagram of the interpolation of the interpolation circuit 50. 16: Video / still image converter, 18: Color printer, 42: 1
9: frame memory, 20: enlargement processing circuit, 22: motion detection interpolation circuit, 24: color conversion circuit, 30, 32, 34, 36, 38, 40: memory, 4
2: motion vector detection circuit, 44: motion amount judgment circuit, 46, 48, 5
0: interpolation circuit

Claims (1)

(57) [Claims] An image memory capable of storing image signals of a plurality of fields, enlargement means for enlarging the image signals of the plurality of fields stored in the image memory, and an image signal of the plurality of fields enlarged by the enlargement means Detecting means for detecting a motion vector; determining the amount of motion based on the detection result of the detecting means based on the characteristics of the printer; and determining the amount of motion to be selected. A color conversion unit for performing color conversion for printing on image signals of a plurality of fields.