Facsimile and static presentation processing – Static presentation processing – Communication
Reexamination Certificate
1998-06-22
2001-09-11
Coles, Edward (Department: 2722)
Facsimile and static presentation processing
Static presentation processing
Communication
C358S001160, C358S001170, C358S001180, C358S001130, C358S001100, C358S001900
Reexamination Certificate
active
06288791
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The invention relates to a multifunction apparatus and, more particularly, to a multifunction apparatus and a picture signal processing method used by the multifunction apparatus.
2. Description of Related Art
A known multifunction apparatus is equipped with a printing function using a laser printer or a color ink jet printer, a scanner function using a charged-couple device (CCD), a copy function, a facsimile function, a personal computer connecting function, and so on.
The multifunction apparatus has a built-in memory that stores various data corresponding to the functions. The built-in memory is used as, for example, a received facsimile data memory, a transmission facsimile data memory, a message recording memory, an answering message memory for an answering phone function, a printer buffer memory, a scanner buffer memory and an image data memory.
SUMMARY OF THE INVENTION
The invention adds, to such a multifunction apparatus, a function of receiving picture signals and performing video-capture of the signals for outputting the image obtained by the video capture to a personal computer. For picture signals, the NTSC system is widely employed. In the NTSC system, a frame is formed by two fields, with a field being a basic unit. That is, since the NTSC system employs interlace scanning, one field in the NTSC system forms a half frame.
To extract color information and brightness information from signals of the NTSC system, a finite impulse response (FIR) filter can be used. If chrominance signals are extracted from a single field in the NTSC system using an FIR filter, the low-quality problem of extracted chrominance signals arises despite the minimum memory capacity required (corresponding to a half (½) frame). That is, since a field merely forms a half frame, the resolution is low. Moreover, the processing performance of FIR filters is limited. Therefore, the extraction of chrominance signals from one field using an FIR filter suffers from low resolution and low quality due to color information extraction based on a comparison of adjacently-located color information pieces.
If a picture plane is formed from one frame, that is, two fields, chrominance signals are extracted from two fields using an FIR filter, so that the signal extraction requires a larger memory capacity than the aforementioned signal extraction from a single field. However, the required memory capacity is still relatively small (corresponding to one frame), and an intermediate image quality is achieved. Although the image quality is thus improved, the processing using the FIR filter presents limitations in resolution and quality as in the aforementioned single-field signal extraction.
In the case of a static picture image in the NTSC system, two frames, that is, four fields, may be used to form one picture plane, by extracting chrominance signals based on differentials between the two frames. Since two consecutive frames in the NTSC system shift 180° in phase, the differentials between frames makes it possible to extract chrominance signals to a great extent. Therefore, the image quality is good (owing to the frame differentials). However, a large memory capacity is necessary.
Allotting a large space of a memory to the conversion from picture signals into image data leads to inefficient use of memory because the various other functions of the multifunction apparatus also require large memory spaces. If a memory dedicated to image data is provided, the cost of the entire apparatus is very high as the memory for the picture signal processing needs to have a high speed and a large capacity.
Because it is rare that all functions operate simultaneously, it is an object of the invention to provide a multifunction apparatus that changes a mode of conversion of a picture signal into image data in accordance with the memory space that is being used for functions other than the picture signal processing, so as to efficiently use the memory, improve the image quality and reduce the manufacturing costs, while providing a picture signal processing method performed by the multifunction apparatus.
According a first aspect of the invention, there is provided a multifunction apparatus including a reception device for receiving a picture signal, and conversion device for converting the picture signal received by the reception device, into image data. A storage device is provided for storing the image data obtained through conversion by the conversion device. The storage device is usable also for an operation other than an operation related to the conversion by the conversion device. A detection device is provided for detecting an amount of memory space available in the storage device. A conversion mode changing device is provided for changing a mode of conversion by the conversion device, on the basis of the result of the detection by the detection device.
The conversion device may employ at least one of a two-frame differential mode in which color information and brightness information are extracted based on differentials between two frames, and an FIR filtering mode in which color information and brightness information are extracted using an FIR filter.
The conversion mode changing device may set the mode of conversion to one of the two-frame differential mode and the FIR filtering mode on the basis of the amount of available memory space in the storage device detected by the detection device.
The conversion mode changing device may set the mode of conversion to the two-frame differential mode if the amount of available memory space in the storage device detected by the detection device is equal to or greater than a first predetermined amount. The conversion mode changing device may also set the mode of conversion to a two-field FIR filtering mode if the amount of available memory space in the storage device detected by the detection device is less than a first predetermined amount but greater than or equal to a second predetermined amount. The conversion mode changing device may also set the mode of conversion to a one-field FIR filtering mode if the amount of available memory space in the storage device detected by the detection device is less than a second predetermined amount but greater than or equal to a third predetermined amount.
The first predetermined amount may be 806,400 bytes, the second predetermined amount may be 403,200 bytes, and the third predetermined amount may be 201,600 bytes.
The picture signal received by the receiving device may be a video signal.
According to a second aspect of the invention, there is provided a multifunction apparatus including a receiver unit that receives a picture signal and a converter unit that converts the picture signal received by the receiver unit into image data. A storage unit stores the image data obtained through conversion by the converter unit. The storage unit is usable also for an operation other than an operation related to the conversion by the converter unit. A detector unit detects an amount of memory space available in the storage unit. A conversion mode changer unit changes a mode of conversion by the converter unit, on the basis of the result of detection by the detector unit.
The conversion mode changer unit may set the mode of conversion to one of a two-frame differential mode in which color information and brightness information are extracted based on differentials between two frames, and an FIR filtering mode in which color information and brightness information are extracted using an FIR filter, on the basis of the amount of available memory space in the storage unit detected by the detector unit.
The conversion mode changer unit may set the mode of conversion to the two-frame differential mode if the amount of available memory space in the storage unit detected by the detector unit is equal to or greater than a first predetermined amount.
The conversion mode changer unit may set the mode of conversion to a two-field field FIR filtering mode if the amount of available memory space in the storag
Brother Kogyo Kabushiki Kaisha
Coles Edward
Lamb Twyler
Oliff & Berridg,e PLC
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