Computer graphics processing and selective visual display system – Computer graphic processing system – Interface
Patent
1997-12-08
2000-05-30
Bayerl, Raymond J.
Computer graphics processing and selective visual display system
Computer graphic processing system
Interface
345515, 345516, 345509, 36518901, 36523002, G06F 1316
Patent
active
060696397
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a video camera system and a graphic memory circuit, and particularly to a graphic memory circuit utilizing a dynamic random access memory (DRAM).
BACKGROUND ART
Conventionally, in a general purpose memory conforming to international standards for DRAMs, since control methods for these devices are common throughout the world, general purpose controllers for controlling such memory devices inevitably exist. Also, it is common place for a general main processor unit (MPU) to have a standardized general purpose memory controller built in.
On the other hand, since a general purpose controller can not be used with a non-general purpose memory, users must develop their own custom controller.
Conventional non general purpose memories have been developed to satisfy demands that can not be achieved using general purpose memories.
Maintaining the functions of the non-general purpose application, use of accumulated information stored inside the memory would be extremely convenient if this information could be directly accessed from a general purpose DRAM controller or an MPU having a general purpose DRAM controller.
Non general purpose memories are basically being designed making use of general purpose memories. Accordingly, it is possible to improve the design of control input signals that are extremely similar to those of a general purpose DRAM. However, it is not possible to achieve exactly the same control.
The timing of DRAM control signals generated from a DRAM controller and the timing at which memory output is latched is fixed, which means that it is extremely difficult to provide memory control that improves on control that is very similar that of general purpose DRAM.
Signals are output from a memory side to a memory controller of an MPU, and the basic concept of the present invention is to control the operation of the controller or MPU.
A specific example of a system using the conventional method will now be described.
A keyboard or a mouse is a human interface for a personal computer (hereinafter referred to as a PC). However, a digital video camera has recently become popular as a human interface. It is possible to transfer a digital image taken by the digital camera to a PC.
An dedicated memory called a field memory (referred to as FRAM below) is usually used in a digital camera (operation will be described later). A simplified block diagram of a video camera system that can transfer a digital image to a PC is shown in FIG. 1.
The operation of the video camera system of FIG. 1 will now be described.
First of all, the video camera section A will be described. An image (a) is taken in and a charged coupled device (CCD) (B) generates corresponding analog data (b). This analog data (b) is converted into digital data by an analog to digital converter (A/D) (C), and is input to the FRAM (G). Accumulated digital image data is then processed taking advantage of digital image techniques such as time axis correction and filtering, according to control signals (d) of the controller (D).
On the other hand, when considering an interface between the video camera and a PC, since the image data is extremely large, problems arise such as the fact that a buffer for temporary storage becomes large and the time taken to transfer the image data to the PC becomes excessive. Accordingly, it becomes necessary to compress the image data, and the method generally used is called JPEG compression (actually, there are various compression methods, and the present invention is not limited to JPEG compression, but JPEG compression will be used here). In JPEG compression, complicated computation is required, and the load on an MPU is substantial.
In order to carry out JPEG compression, it is therefore currently necessary to include an MPU (H) and a general purpose DRAM (M, I, J) controlled by the MPU in the conventional video camera section. Functions of the general purpose DRAM, such as a temporary buffer (M), a compression data buffer (I), and a work area (J) are separated.
The MPU
REFERENCES:
patent: 4710903 (1987-12-01), Hereth et al.
patent: 4899316 (1990-02-01), Nagami
patent: 5646684 (1997-07-01), Nishizawa et al.
patent: 5805518 (1998-09-01), Hashimoto et al.
Bayerl Raymond J.
Luu Sy D.
OKI Electric Industry Co., Ltd.
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