JP2002314878A - Method for reproducing variable image size - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for reproducing a variable image size in which an aliasing free high image quality reproduction interlaced scanning image can be obtained constantly with an appropriate resolution even if the image size is altered through magnification/contraction incident to image reproduction. SOLUTION: When a dynamic image (interlaced scanning image) having an image size different from the essential image size of an incoming dynamic image is outputted, a reproduction image is temporarily obtained as a sequential scanning image thus producing a signal in which resolution is extended by suppressing an aliasing component included in the interlaced scanning image. Image size is altered while keeping a signal appropriate as a sequential scanning image by magnifying/contracting the reproduction image, i.e., the sequential scanning image. The sequential scanning image having an altered image size is decimated in accordance with the format of an output interlaced scanning image thus producing an aliasing free appropriate interlaced scanning image in which lowering of resolution is prevented while altering the image size.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention enlarges or reduces the size of a part or all of a reproduced image when reproducing a moving image signal and outputting a moving image to a display device or the like. The present invention relates to a variable image size reproducing method, and particularly to a variable image size reproducing method for outputting as an interlaced scanning image.

[0002]

2. Description of the Related Art <Variable image size reproduction> There are various moving image formats in digital broadcasting, and a signal of a moving image format different from a displayable moving image format is sometimes reproduced. Also, in the multimedia display,
It is necessary to display still images and character information other than the main moving image on the same screen, and the moving image is displayed smaller than the original image size (original number of scanning lines and pixels). Further, in image display, a zoom function for enlarging only a desired portion of the image is required.

In these cases, part or all of the reproduced image is converted into an image having a different number of scanning lines from the original number of scanning lines. However, in a moving image signal of interlaced scanning, Enlargement / reduction processing is performed in each field. In the interlaced scanning, one frame is composed of two fields, an odd field and an even field. Therefore, if the enlargement / reduction processing is performed on a frame basis, two fields that are temporally shifted are mixed, resulting in remarkable image quality deterioration. For this reason, enlargement / reduction processing is performed on a field basis. <Conventional Variable Image Size Reproducing Apparatus> FIG. 3 shows a conventional example of a variable image size reproducing apparatus.

The code sequence of a moving image coming from the code input terminal 1 is reproduced by the decoder 2 as an interlaced scanning image of the original image size of the incoming moving image. The decoded interlaced scanning image is subjected to size information (image size control information) coming from the size information input terminal 8 by the size changer 31.
Are enlarged or reduced in accordance with, and are converted into interlaced scan images of different image sizes. The interlaced scan image whose contents have been changed is output from the image output terminal 7.

[0005] In the size change, in addition to the enlargement / reduction ratio, positional information on which part of the image is to be enlarged and where the reduced image is to be arranged is required.

[0006] The size change is a resampling and a spatial position change of an image. Resampling is implemented with a filter having multiple sample phases. The resampled image is stored in the image memory, and is read out at the same speed as the original image, so that the spatial position is changed.

FIG. 4 shows the state of these processes. FIG.
/ 2 reduction and 2x magnification. All processes are performed on a field basis.

[0008]

In the conventional variable image size reproducing apparatus, since the resampling process is performed in the field of the interlaced scan image when the size is changed, the positional relationship between the even and odd numbers of the scanning lines is lost. Become. Therefore, the aliasing distortion component of the original interlaced scanning image does not contribute to the improvement of the resolution in display, and is merely a noise component. As a result, resolution reduction and aliasing (image quality deterioration such as diagonal lines becoming step-like) have occurred.

The present invention has been made in view of the above points, and is intended to output a moving image (interlaced scanning image) having an image size different from the original image size of an incoming moving image (ie, a variable image size). It is another object of the present invention to provide a variable image size reproducing method capable of obtaining an appropriate interlaced scanning image without degradation in resolution and without aliasing during reproduction.

[0010]

Therefore, in order to solve the above-mentioned problems, the present invention provides the following method. (1) In a variable image size reproducing method for reproducing an incoming moving image signal and outputting a moving image converted to an image size different from the original image size of the incoming moving image, reproducing the incoming moving image signal And an image reproduction step of obtaining a reproduction interlaced scan image having an original image size of the incoming moving image,
A scanning line conversion step of converting the reproduced interlaced scanning image into a sequential scan to obtain a reproduced sequential scanning image, and resampling a part or the whole of the reproduced sequential scanning image, An image size changing step of changing to an image having a different number of scanning lines from the number of scanning lines and obtaining a display interlaced scanning image having a different image size from the reproduced interlaced scanning image; and an original image of the incoming moving image. When outputting a moving image of a size, the reproduction interlaced scanning image is selected and output, and when a moving image having an image size different from the original image size of the incoming moving image is output, the An image selection step of selecting and outputting a display skip scanning image and outputting the variable image size reproduction method. (2) A variable image that reproduces an incoming moving image signal that can be reproduced by both interlaced scanning and sequential scanning, and outputs a moving image converted to an image size different from the original image size of the incoming moving image In the size reproducing method, when a moving image having the original image size of the incoming moving image is output, the incoming moving image signal is reproduced to reproduce the interlaced scanning image which is the original image size of the incoming moving image. Obtaining a moving image having an image size different from the original image size of the incoming moving image, an image reproducing step of reproducing the incoming moving image signal to obtain a reproduced sequential scanning image, By resampling a part or all of the reproduced sequential scanning image, the image is changed to an image having a different number of scanning lines from the number of scanning lines of the reproduced sequential scanning image. Was An image size changing step of obtaining a display interlaced scan image, and in the case of outputting a moving image of the original image size of the incoming moving image, selecting and outputting the reproduced interlaced scanning image, and If you want to output a moving image with an image size different from the original image size,
An image selecting step of selecting and outputting the interlaced scanning image and outputting the image.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a case where a moving image (interlaced scanning image) having an image size different from the original image size of an incoming moving image is output (that is, when reproducing a variable image size).
First, a reproduced image is once obtained as a sequentially scanned image, so that the aliased distortion component included in the interlaced scanned image is suppressed, and the reproduced image is converted into a signal having an increased resolution. By scaling up or down the reproduced image, which is a progressively scanned image, the image size is changed while maintaining a proper signal as the progressively scanned image. By skipping the progressive scan image with the changed image size in accordance with the format of the interlaced scan image for output, an appropriate interlaced scan image without resolution reduction or aliasing is output as the image size is changed. can get. <First Embodiment> A variable image size reproducing apparatus using the first embodiment of the variable image size reproducing method will be described. The configuration is shown in FIG. The same components as those in the conventional example of FIG. 3 are denoted by the same reference numerals. FIG. 1 is different from FIG. 3 in that a sequential scan converter 3, a scanning line thinning device 5, and an image switch 6 are added. Also, the operation of the size changer 4 is different.

The size information terminal 8 is supplied with size information relating to the image size (image size control information). The enlargement and reduction rates are 1 to 4 times for enlargement and 1 to 1/1 / reduction.
4 times. Also, the target area for changing the size (start horizontal position, start vertical position, end horizontal position, end vertical position),
The inset area (start horizontal position, start vertical position, end horizontal position, end vertical position) of the image after the change is also given as needed. The size information is supplied to the size changer 4 and the image switch 6, and controls the size changer 4 and the image switch 6.

The moving image signal (moving image signal to be reproduced) coming from the code input terminal 1 is of an interlaced scanning image, and the image format is NTSC signal or 480.
i, a digital signal called 1080i. All image rates are 60 fps (frame per second).

The signal form may be an analog signal, an uncompressed digital signal, an intra-frame compression code string, an inter-frame compression code string according to MPEG-2, or the like. The decoder 2 performs a decoding process suitable for the signal form, obtains an image signal of interlaced reproduction, and supplies it to the sequential scan converter 3 and the switch 6. When there is no enlargement / reduction (when a moving image having the original image size of the incoming moving image is output), the reproduced interlaced scanning image is output from the image output terminal 7 via the image switch 6.

The progressive scan converter 3 performs scanning line interpolation on the reproduced interlaced scan image, obtains a progressive scan image, and supplies it to the size changer 4. Here, if the conversion processing is appropriate, the obtained reproduced progressively scanned image is close to the progressively scanned image before being skipped by the interlaced scanning, and the resolution is improved.

The reproduced progressively scanned image becomes a display progressively scanned image whose image content has been changed at least by the size changer 4 in the vertical direction, and is supplied to the scanning line thinning device 5. In the size changer 4, the conventional size changer 3 shown in FIG.
Resampling and spatial alignment are performed as in 1. However, while the size changer 31 is for a field, the size changer 4 of FIG. 1 performs processing for each frame of progressive scanning. The frequency characteristic of the resampling filter is changed at the time of reduction in accordance with the reduction ratio. Before and after this processing, the format of the image has not changed.

The display sequential scanning image whose image content has been changed is thinned out by the scanning line thinning device 5 in synchronization with the output interlaced scanning image and output as a display interlaced scanning image.
The switch 6 outputs the reproduced interlaced scanning image decoded by the decoder 2 as it is when there is no enlargement / reduction (when a moving image having the original image size of the incoming moving image is output). When scaling is performed (when outputting a moving image having a different image size from the original image size of the incoming moving image),
The display skip scanning image output from the scanning line thinning device 5 is selected. Both the reproduction interlaced scanning image and the display interlaced scanning image are output from the image output terminal 7 as interlaced scanning images of the same format.

FIG. 5 shows the state of the scanning lines in this embodiment. The playback interlaced scanning image and the display interlaced scanning image are the same as those shown in FIG. The progressive scan image obtained by the progressive scan conversion in FIG. 5 includes an original scan line indicated by a circle (○) and an interpolation scan line indicated by a diamond (◇). In the image size change, the image size is changed as a progressively scanned image without distinction. The resampled image is temporarily stored in a memory, output in synchronization with the input image, and has the same format as the original progressively scanned image. The contents of the image have been scaled up and down.

FIG. 6 shows the state of the image vertical spectrum in this embodiment. The vertical frequency is when the number of effective scanning lines is 480 per frame, and the frequency is cph (cycle per cycle).
height). In the reproduction interlaced scanning image shown in FIG. 6A, the spectrum has a folded component at 80 cph or more. When this is sequentially scanned, the aliasing component disappears and a spectral component exists up to 160 cph, as in the reproduced progressively scanned image shown in FIG.

When this is enlarged or reduced, the spectrum is extended to a higher side in the reduction as shown in the display sequential scanning image shown in FIG. In the case of 1/2 times, it will grow up to 2 times, so 240
If it is cph or more, it will be folded back up to 160 cph. Here, since 160 cph or more causes flicker in interlaced scanning, the frequency characteristics of the resample filter are devised, and
Suppress above cph. As a result, there are no aliasing components. When this is thinned out and becomes d) a display interlaced scan image, an image having an appropriate spectrum as the interlaced scan image is obtained similarly to the reproduced interlaced scan image.

On the other hand, when the image is enlarged, the vertical spectrum of the image is shrunk.
cph). In this case, the resampling filter may have a frequency characteristic corresponding to the original image. Even if this is decimated and becomes the interlaced scanning image shown in FIG. 4D, there is no problem as the interlaced scanning image and the spectrum is maximized, so that the maximum resolution can be obtained.

It is also possible to integrate the processing of the size changing unit 4 and the processing of the scanning line thinning unit 5 and obtain a display skip scanning image directly from the reproduced sequential scanning image by resampling. In this case, resampling and storage and readout in the memory are performed only on the scanning lines remaining in the interlaced scanning.

As described above, in this embodiment, even if the image size is changed, such as enlargement or reduction, in accordance with the image reproduction, a high-quality reproduction interlaced scan image with an appropriate resolution and no aliasing can always be obtained. <Second Embodiment> A variable image size reproducing apparatus using a variable image size reproducing method according to a second embodiment will be described. The configuration is shown in FIG. The same components as those of the apparatus according to the first embodiment of FIG. 1 are denoted by the same reference numerals. In FIG. 2, a switch 22 is provided instead of the progressive scan converter 2 as compared with FIG. 1, and the operation of the decoder 21 is different.

The second embodiment differs from the first embodiment in that a progressively scanned image is reproduced by decoding. The basic concept of processing is the same.

The decoder 21 decodes a code string in accordance with the size information. In the case of normal reproduction without scaling (in the case of outputting a moving image of the original image size of an incoming moving image), The reproduction interlaced scanning image having the original image size of the incoming moving image is obtained, and the obtained image is provided to the switch 6 via the switch 22. On the other hand, when scaling is performed (when a moving image having an image size different from the original image size of the incoming moving image is output), the decoder 21 obtains a reproduced progressively scanned image and obtains an image size changer. Give to 4.

Here, the decoder 21 can obtain both an interlaced scan image and a progressive scan image by changing the decoding processing form for a predetermined type of code string. A specific example of a predetermined type of code sequence is MPEG
I-pictures and P-pictures, which are code strings formed by high-efficiency coding of the
The picture includes a code string encoded by interlaced scanning. An encoding device for obtaining such a code sequence and a decoding device for reproducing the code sequence as a progressively scanned image are disclosed in Japanese Patent Laid-Open No. 11-46 by the same applicant as the present invention.
365.

In the second embodiment, as in the first embodiment, even if the image size such as enlargement or reduction is changed during image reproduction, high quality reproduction interlaced scanning without aliasing is always performed at an appropriate resolution. An image is obtained.

[0028]

As described above, according to the present invention, when outputting a moving image (interlaced scanning image) having an image size different from the original image size of the incoming moving image (that is, at the time of reproducing the variable image size), Once the reproduced image is obtained as a sequentially scanned image, the reproduced image is converted into a signal with an increased resolution by suppressing aliasing components included in the interlaced scanned image. By scaling up or down the reproduced image, which is a progressively scanned image, the image size is changed while maintaining a proper signal as the progressively scanned image. By skipping the progressive scan image with the changed image size in accordance with the format of the interlaced scan image for output, an appropriate interlaced scan image without resolution reduction or aliasing is output as the image size is changed. can get.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration example of a variable image size reproduction device according to a first embodiment.

FIG. 2 is a diagram illustrating a configuration example of a variable image size reproducing device according to a second embodiment.

FIG. 3 is a diagram illustrating a configuration example of a conventional variable image size reproducing device.

FIG. 4 is a diagram showing a state of scanning lines in variable image size reproduction according to a conventional example.

FIG. 5 is a diagram illustrating a state of scanning lines in variable image size reproduction according to the embodiment.

FIG. 6 is a diagram illustrating a state of an image vertical spectrum in variable image size reproduction according to the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Code input terminal 2, 21 Decoder 3 Progressive scan converter 4, 31 Image size changer 5 Scan line thinning device 6, 22 Image switch 7 Interlaced scan image output terminal 8 Size information input terminal

Claims (2)

[Claims] 1. A variable image size reproducing method for reproducing an incoming moving image signal and outputting a moving image converted to an image size different from the original image size of the incoming moving image. An image reproducing step of reproducing the received interlaced moving image to obtain a reproduced interlaced scanning image which is the original image size of the incoming moving image; and The conversion step, by resampling a part or all of the reproduced progressively scanned image, to change the number of scanning lines different from the number of scanning lines of the reproduced progressively scanned image, the reproduced interlaced scanned image and Is an image size changing step of obtaining a display interlaced scanning image having a different image size; and selecting the reproduction interlaced scanning image when outputting a moving image having the original image size of the incoming moving image. Output
When outputting a moving image having an image size different from the original image size of the incoming moving image, an image selecting step of selecting and outputting the display skip scanning image is provided. Variable image size playback method. 2. An incoming moving image signal which can be reproduced by any of interlaced scanning and sequential scanning is reproduced, and a moving image converted to an image size different from the original image size of the incoming moving image is output. In the variable image size reproducing method, when a moving image having the original image size of the incoming moving image is to be output, the incoming moving image signal is reproduced to skip the reproduction which is the original image size of the incoming moving image. Obtaining a scanned image and outputting a moving image having an image size different from the original image size of the incoming moving image, an image reproducing step of reproducing the incoming moving image signal to obtain a reproduced sequential scanning image; By resampling a part or all of the reproduced progressively scanned image, the reproduced progressively scanned image is changed to an image having a different number of scanning lines from the number of scanning lines of the reproduced progressively scanned image. of An image size changing step of obtaining a display interlaced image becomes, in the case of outputting a moving image of the incoming video image original image size, selects and outputs the reproduced interlaced image,
When outputting a moving image having an image size different from the original image size of the incoming moving image, an image selecting step of selecting and outputting the display skip scanning image is provided. Variable image size playback method.