JP3154272B2 - Image conversion apparatus and method - Google Patents

Description

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

2. Description of the Related Art Conventionally, there has been a request to print or print a specific instantaneous image 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 more than five times the amount of information, so that it can withstand viewing even as a still image. Further, with the advance 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 shadow image 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, the moving amount and direction of the moving object between the fields are obtained by a motion vector detection method typified by a matching method or a density gradient method, and the shifted image is corrected based on this to form a clear still image without a shift. A conversion device has been 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 and method for improving the quality of an image for printing.

[Means for Solving the Problems] An image conversion apparatus according to the present invention stores an image signal of a plurality of fields in an image memory, and detects a motion vector from the image signals of the plurality of fields stored in the image memory. Detecting means, determining the amount of motion based on the detection result of the detecting means based on the characteristics of the printer, and determining the interpolating means to be selected; and the image signals of the plurality of fields interpolated by the interpolating means. And color conversion enlargement means for performing enlargement and color conversion for printing.

An image conversion method according to the present invention includes a storage step of storing image signals of a plurality of fields in an image memory, a detection step of detecting a motion vector from the image signals of a plurality of fields stored in the image memory, The motion amount is determined based on the characteristics of the printer based on the detection result, and a motion amount determining step of determining an interpolation unit to be selected.Enlargement and printing for the image signals of the plurality of fields interpolated by the interpolation unit are performed. And a color conversion enlarging step for performing color conversion.

[Operation] By the above means, appropriate interpolation according to the amount of motion of an image can be performed, and therefore, image quality deterioration due to the interpolation processing can be suppressed to the minimum.

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

FIG. 2 is a schematic block diagram showing a configuration in which a still image is obtained from a moving image source using the conversion device according to the present invention, and is output by a printer. Reference numeral 10 denotes a TV camera, 12 denotes a video tape playback device, 14 denotes a television receiver, and a moving image signal obtained from these is input to an image conversion device 16 according to one embodiment of the present invention, and is output to a printer. Is formed. The output of the image converter 16 is applied to a color printer 18 and printed on paper.

The image conversion device 16 is generally composed of a frame memory 20 for storing a video signal of an arbitrary frame among the moving image signals from the TV camera 10, the video playback device 12, or the television receiver 14, and a frame memory. A motion detection interpolation circuit 22 for detecting a motion belt from the odd-field and even-field video signals stored in 20, and interpolating according to the detection result, and color-converting the interpolated image signal for the color printer 18. And a color conversion enlargement circuit 24 for enlargement (or reduction). In this embodiment, the color conversion enlargement circuit 24, YP _R P _B
(Luminance / color difference) signal is converted to MYCBk signal.

FIG. 1 is a block diagram showing a more detailed circuit configuration of the image conversion device 16. The frame memory 20 includes memories 30, 32, and 34 for odd fields and memories 36, 38, and 40 for even fields. A luminance signal Y is stored in the memories 30 and 36, and a color difference signal P is stored in the memories 32 and 38. _R, in the memory 34, 40 is stored chrominance signals P _B.

A motion vector detection circuit 42 detects a motion vector from the data stored in the memories 30 and 36 of the luminance signals of the odd field and the even field by the above-described known method. As a reference, a signal indicating in which direction and how much the corresponding pixel in the other (odd fibold) 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 the object format itself is difficult to recognize. 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. In addition, "Evaluating the detected motion vector based on the characteristics of the printer" according to the present invention has been described above as selecting from three types of interpolation methods. There may be more than one. Further, the interpolation circuits 46, 48, and 50 may be configured by different hardware, or may be configured by one data processing device, and the interpolation operation may be switched by software.

Although the two field pictures to be compared have been described with respect to the field that is closest in time, the comparison may be made between arbitrary fields, and the present invention is not limited to the combination of rare fields and even fields. The input signal is YP _R P
_In addition to the _B signal, it may be an RGB signal or the like, and the converted signal is also YMCB
It is not limited to k signals. 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 detected motion vector is evaluated according to parameters based on printer characteristics, and a plurality of fields are evaluated by a method according to the evaluation result. Interpolates the image signal,
Since enlargement and color conversion for printing are performed, it is possible to improve the quality of the printed image as compared with the related art.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is an example of the configuration used in the embodiment of FIG. 1, FIG. 3 is an explanatory diagram of the interpolation by the interpolation circuit 46 of FIG. 5 is an explanatory diagram of the interpolation of the interpolation circuit 48, and FIG. 5 is an explanatory diagram of the interpolation of the interpolation circuit 50. 16: Image conversion device, 18: Color printer, 42: 20: Frame memory, 22: Motion detection interpolation circuit, 24: Color conversion expansion circuit, 30, 32, 34, 36, 38, 40: Memory, 42: Motion vector detection circuit, 44: motion amount judgment circuit, 46, 48, 50: interpolation circuit

Claims (2)

(57) [Claims] 1. A means for storing image signals of a plurality of fields in an image memory, a detecting means for detecting a motion vector from the image signals of a plurality of fields stored in the image memory, and a motion amount based on a detection result of the detecting means. Motion amount determining means for determining interpolation means to be selected based on the characteristics of the printer, and a color for performing enlargement and color conversion for printing on the image signals of the plurality of fields interpolated by the interpolation means. An image conversion device, comprising: conversion enlargement means. A storage step of storing image signals of a plurality of fields in an image memory; a detection step of detecting a motion vector from the image signals of a plurality of fields stored in the image memory; A motion amount determining step of determining the amount based on the characteristics of the printer and determining an interpolation means to be selected; and performing enlargement and color conversion for printing on the image signals of the plurality of fields interpolated in the interpolation direction. An image conversion method, comprising: a color conversion enlargement step.