JP3901869B2 - Memory device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image memory, and more particularly to an image memory that is used for both temporary storage and storage of image data, and is used for temporarily storing, editing, or storing image data in, for example, a scanner, a printer, a facsimile machine, and a copying machine. This is an image memory that can easily and efficiently control the memory capacity of both the work area for editing and the image storage area for electronic sorting.
[0002]
[Prior art]
This type of image memory is used as a buffer memory for image data to be output to a printer, or is used to scan a one-page or two-page document for image editing on a one-page image or between two-page images. It is used for writing image data, or it is used for sequentially storing image data of a plurality of originals, so-called electronic sort. When writing image data, free space in the memory is searched and written sequentially into the free space, but if writing is not completed in a wide area with continuous addresses, it is written in a jump. It is.
[0003]
[Problems to be solved by the invention]
In the conventional memory writing control method, a method of simply changing the mapping has been adopted when divided into a plurality of uses such as an electronic sort. In this method, memory management such as designation of a write start address and memory address control is complicated when it is desired to change the use area depending on the application. For example, when calculating the image data storage capacity from the work area required capacity, the work area used depends on the document size and image editing function, but it is necessary to change the start address and calculate the free space each time. . Further, when the memory becomes full during the electronic sort process or the like, only the normally processed data is printed. However, it is difficult to determine whether the process is abnormal just by looking at the printed document.
[0004]
The first object of the present invention is to facilitate the setting of both write start addresses when the same memory area is divided into a work area and an image storage area. A second object is to facilitate the memory control by always using the free area as a linear address space. The third object is to simplify memory management, for example, by automatically controlling the start address of an additional page even when a plurality of areas such as a plurality of pages of different sizes are set in the work area. And A fourth object is to reliably notify the operator that a memory overflow has occurred.
[0005]
[Means for Solving the Problems]
(1) Memory with linear address space (1);
Work area writing means (21-23) for writing image data to the work area (1w) in which the write start address is set to one of the maximum address (SOW) and the minimum address (SOC) of the memory space of the memory , 25, 3);
Storage that writes compressed data of image data read from the work area (1w) to the storage area (1a) in which the write start address is set to the other (SOC) of the maximum address (SOW) and minimum address (SOC) Area writing means (24, 25, 3);
One more page from the end address (EOW) that can store one or more pages of image data in the work area (1w) and the end address (EOC2) that has already stored compressed data in the storage area (area 2 of 1a). If there is a free space (1e) between the address obtained by shifting an address for storing the image data (EOC1) the ((1) If expression is satisfied), the image data of the new page work The end that can write to the area (1w) and store the compressed data of the image data in the storage area (area 1 of 1a) and store one page of image data as the minimum value in the work area (1w) between the address (EOW) and the storage area address already shifted address for storing image data of further one page from accumulated end address (EOC2) compressed data (area 2 1a) (EOC1) When there is no more free space in No address space exists between the end address (EOW) that can store one page of image data in the work area (1w) and the end address (EOC2) that stores the compressed data (Equation (2) is not satisfied) ) Sometimes the writing of a new page of image data to the work area (1w) does not start, and when the address space exists (Equation (2) holds), the work area of the new one page of image data A memory device comprising control means (2) for starting writing to (1w) and storing the compressed data of the image data in the storage area (area 1 of 1a).
[0006]
In addition, in order to make an understanding easy, the code | symbol of the corresponding element or the corresponding matter of the Example shown in drawing and mentioned later in parentheses is added for reference. The same applies to the following.
[0007]
This facilitates address management for data writing and reading in the work area (1w) and the storage area (1a). Further, the free area (1e) can always have a linear address space (SOA to EOA), so that the memory can be used without waste and the read / write address control of the memory can be easily performed. Also, the document size in the work area (1 w) can easily accommodate be set to any size, Ru set easy der multiple original area. In the process involving images storage, Memorio - because if less likely to back are sweetened memory management Paphos - it is possible to raise to maximize performance.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
(2) The control means (2) sets an end address (EOW) capable of storing a plurality of pages of image data in the work area (1w), and sets the end address (EOW) and the storage area (1a). When there is no free space between the area 2) of the address already shifted address for storing image data of further one page from accumulated end address (EOC2) compressed data (EOC1), successively the workpiece The memory device according to (1), wherein the end address (EOW) of the area (1w) is changed in a direction of narrowing by an address space capable of storing one page of image data.
[0009]
According to this, since it is possible to increase the productivity of electronic sorting and double-sided reading by using a work area for a plurality of pages , the work area can be increased and decreased and the area secured while monitoring the remaining memory capacity. Therefore, it is possible to maintain optimum productivity with simple memory control.
[0010]
(3) End address (EOW) that can store one page of minimum image data in the work area (1w) and end address (EOC2) that has already accumulated compressed data in the accumulation area (area 2 of 1a) If the free space runs out between more and 1-page image data address obtained by shifting an address for storing the data of the (EOC1) from the end capable of storing image data of one page in the work area (1 w) There is an address space between the address (EOW) and the end address (EOC2) that stores the compressed data (Equation (2) holds), and a new page of image data to the work area (1w) When the memory is over after starting to write, the control means (2) stops writing the image data of the document to the work area (1w) and the corresponding page of the storage area (1a) Decompress the compressed data into image data The memory device according to (1) or (2), wherein when outputting, the invalid area is image data for representing an overflow.
[0011]
For example, the invalid area data is completely whitened. Even if a memory overflow occurs, the remaining image of the corresponding page is completely whitened, so that the operator can reliably recognize that a memory overflow has occurred. Alternatively, the polarity of the decompressed (decoded) image data of the valid data portion is inverted and transferred. If this is output, black-and-white reversal occurs in the middle of a normal document image, so that the operator can determine that a memory overflow, that is, an accumulation error has occurred. In addition, addition of information representing an image error, for example, insertion of “ERROR” into the error area may be performed.
[0012]
(4) One of the maximum address (SOW) and the minimum address (SOC) is one of the maximum address (SOW) and the other is the minimum address (SOC) , according to any one of (1) to (3) above of the memory device.
[0013]
(5) above (1) to (4) memory device (1-3) according to any one of;
Encoding / decoding means (4) for compressing image data stored in the storage area of the memory device and decoding compressed data read from the storage area into image data ; and
The encoding / decoding means (4) is decoded is written to the work area (1 w) by, and the image writing means (7 to form an image represented by the image data read from the work area (1 w) ~ 9) An image forming apparatus comprising:
[0014]
(6) reads an image of a document, the document reading means for outputting a memory device image data to which the written in the work area (1 w) of (1) to said memory device (1) (5-7); further comprising The image forming apparatus according to (5) above.
[0015]
Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.
[0016]
【Example】
FIG. 1 shows a configuration example of the image memories (1 to 3) to which both the work area 1w and the image storage area 1a are allocated. The work area 1w is a memory area for temporarily storing original reading data in binary or multi-value values for image editing or the like, and is usually configured by a DRAM. Editing functions often used on digital copiers are those with one original or two originals, such as the aggregation function (2in1, 4in1) and the halftone function (regular pattern is placed on a white background). There are some which superimpose the above originals, but various editing functions are conceivable. In addition, there is an electronic sort function that is effective when copying a large number of originals in multiple copies. In order to make effective use of memory resources for electronic sorting, data that has undergone image compression is usually stored in HD (hard). To disk) or memory. In this embodiment, the area control 2 shown in FIG. 1 is a part (partial function) of a memory controller that controls reading and writing of the image memory 1 of the digital copying machine.
[0017]
FIG. 2 shows processes (1) to (6) in which image data in the work area 1w on the image memory 1 is compression-encoded (data compression) and written in the storage area 1a, and the compressed data in the storage area 1a is expanded ( decoding) to indicate the write-free process (7) to (12) in the work area 1 w.
[0018]
Referring to FIG. 1 again, when image storage in the work area 1w is performed, the area control 2 receives document size information or area information on the document from a CPU (hereinafter referred to as host CPU) of a system controller (not shown). Originally, the read document size is set by the work area main scanning setting unit 21 and the work area sub-scanning setting unit 22. The image input data is transferred to the memory control unit in synchronization with the line synchronization signal / LSYNC, the sub-scanning valid signal / FGATE, and the pixel clock ECK. It should be noted that the slash “/” in the alphabetic signal symbol “/ LSYNC” in the drawings and in this description means an overline (L active). The work area control signal generation unit 23 generates a read / write control signal to the work area 1w based on these synchronization signals and the work area main scan / sub scan setting value. On the other hand, when performing electronic sorting, the image data once stored in the work area 1w is compression-encoded by the encoding / decoding unit 4 to secure the storage area 1a set so as not to overlap the work area 1w. Then, the compressed data is written or accumulated there.
[0019]
FIG. 3 shows how to secure the storage area 1a. As shown in FIG. 3A, when the work area 1w is sufficient for one page, [Original Reading-1] is selected, and when two pages of the work area 1w are required, [Original Reading-2] is selected. . As shown in FIG. 3B, when the stored image is output, [ document output-1] and [ document output-2] are obtained, respectively. In the case of encoding, as shown in FIG. 3C, the image data once stored in the work area (1) (image data before compression encoding or decompression decoding: also referred to as raw image data) [Encoding] is to be encoded and written to the storage area. In the case of decryption, the compressed data stored in advance in the storage area is read out, decrypted, and written into the work area (2). This decoded data is the same as the raw image data, and is output by the above-mentioned [Original Output-2]. Although these operations are described as single operations, they may be processed in parallel. In other words, there are a combination of a writing operation and decoding operation of original read image data in the work area (1) and a combination of an encoding process and an output operation from the area (2).
[0020]
Reference is now made again to FIG. [Encoding route] is (1) to (6), and [Decoding route] is (7) to (12). The raw data input & memory control unit 2 outputs raw image data simultaneously with the assertion of RDY1. The encoding processing unit 4 detects DRY1 and, if the reading of the raw image data is OK, samples the raw image data and returns ACK1. If RDY1 is negated, encoding is waited until assertion is detected. When the internal processing ends, the encoding processing unit 4 asserts RDY2 and outputs compressed data. The FIFO control & memory control unit 3 samples the data and returns ACK1 when reading into the FIFO (first-in, first-out buffer memory) is OK. The sampled data is transferred to the FIFO. After a certain amount of data is accumulated in the FIFO, the compressed data is written in a storage area reserved in advance in the DRAM 1. The above is the flow of [encoding route], but [decoding route] has the same basic control except that the data flow is reversed.
[0021]
When reading a document, editing an image, or decoding stored data, the area control 2 designates the number of work areas (WAC). Here, it is “1”. Also set the image size. That is, the main scanning pixel number (PC1) and the sub-scanning line number (LC1) of the read original are set. As a result, the memory capacity required for the work area 1w becomes clear. The start address SOW for storing the first pixel of the read original is set to the maximum address of the memory 1. And the end address EOW of the work area 1w is
EOW = SOW− PC × LC + 1
Automatically determined. And the upper limit address SOA of the memory capacity (empty area) that can be used other than the work area 1w is
SOA = EOW-1
= SOW- PC x LC
It is determined. The address count for writing image data from SOW to EOW is a subtraction count (decrement).
[0022]
FIG. 4 shows the above start and end addresses on the memory 1. When electronic sorting or the like is performed, read image data of an original is stored in the memory 1 after compression processing. Here, description will be made on the assumption that the compression method is performed in units of pages. In the accumulation area 1a for accumulating and storing the compressed data, the least significant 0 address of the memory 1 is set as the accumulation start address SOC. Document read image data (raw image data) once written in the work area 1w is read again, transferred to the encoding processing unit 4, and data compressed. The compressed data is written in the storage area 1a. In writing to the storage area 1a, the storage area control signal generation unit 24 counts up (increments) the memory address for each writing. At this time,
DEF = upper limit address SOA of free area
-End address EOC of storage area
= 0
If the above condition is satisfied, the compressed data writing is stopped. At this time, if the compression process for one page has not been completed, the area control 2 sets the compression error flag CEF to notify the host CPU or the like of an error to the outside of the document reading unit 5 to the memory 1. The document reading operation of the image reading storage system is stopped. In this case, if the DEF has an offset, the accumulation operation can be stopped in a state where a free capacity (SOA to EOA) is secured, and if there is no offset, all the memory areas can be used effectively. is there.
[0023]
Thus, compared with the conventional method, there is a merit that the method of dividing and using the memory and the management of the free space can be simplified. In addition, even if the image size is set to a non-standard size, the memory area can be used for optimal mapping if the main scan and sub scan sizes are known, making it easy to use as an image editing function. It has a configuration.
[0024]
When the number of pages in work area 1w is set to “2”,
End address EOW1 of the first page
= Start address SOW2 of the second page
The end address EOW of work area 1w is
EOW = SOW - (PC1 * LC1 )
+ (PC2 * LC2) +1
It becomes. Therefore, the upper limit address other than the work area, that is, the upper limit address SOA of the free area is
SOA = EOW-1 = SOW - (PC1 * LC1)
+ (PC2 * LC2)
Is calculated by Further, since the write start address SOW2 of page 2 can be confirmed as a monitor register, there is no problem in image editing. As described above, even if the number of pages in the work area 1w increases, if the document size is known, the start address of the added page can be secured following the end address of the first page, so memory control can be performed with a simple operation. Is possible.
[0025]
FIG. 5 shows a state after one page is stored. The compressed data is accumulated in the accumulation area 2. In this state, realm control 2, the following document performs a check can be stored. The end address EOC2 of the storage area 2 (stored data area) is
EOC2 = N-1
It becomes. In order to be able to store the next document, it is necessary to secure a work area for one page.
EOW> EOC1 (1)
Is a condition. However, since ECO1 at this time is added to the storage area 2, if the number of stored data is P1,
EOC1 = (PC × LC + 1) + EOC2
= PC × LC + P1
It becomes. The area control 2 checks this, and if the expression (1) is satisfied, the memory accumulation enable flag (CENB flag) remains on as in the previous case, and the image data accumulation process for the next page document is performed. Do. When the CENB flag is ON, the host CPU (not shown) causes the document reading unit 5 to sequentially read each document. The area control 2 performs the same process as the above process on the document on and after the next page, and performs compression accumulation of the read image data (writing to the accumulation area 1 of the memory 1) as long as the CENB flag is ON. . The area control 2 turns off the CENB flag when the above expression (1) is not established between pages in the middle (during the image reading / accumulating / storing operation of a certain page). In response to this, the host CPU puts on hold the start of reading the next document after the scanning of the current document by the document reading unit 5 is completed.
[0026]
The area control 2 sets a plurality of work areas in advance when the electronic sort (compression of original image data and writing to the storage area 1 ) is performed. That is, a work area for a plurality of documents is set in advance. As a result, the work area is large and the EOW is small. Even under this condition, the success / failure of the CENB flag ON is checked. If it is ON (the ON condition is satisfied), a plurality of work areas can be used, so the productivity of parallel operations on the memory is increased. be able to. In addition, since it can be used in common for other purposes, memory resources can be effectively utilized with a simple system. If the CENB flag is turned off when multiple settings are made, the set value (number of work areas) may be lowered until it is turned on. If the flag is turned off again as the number of accumulated sheets increases, the set value may be further decreased.
[0027]
Even if the CENB flag is not restored to ON even if the work area is lowered to the minimum value, it is possible to decrease the guarantee level and increase the number of stored sheets. This is rarely the case where the compression rate is the same as or higher than that of the original data in a normal text document, and it depends on the compression algorithm, but at least about 10 copies, and if there are many, dozens of copies can be stored. If control is performed while securing a memory area for one page, there is a lot of waste in terms of memory resource utilization, and productivity is reduced more than necessary. Therefore, using ECO2 indicating the end address of the actual stored data instead of ECO1 in the equation (1),
EOW> ECO2 (2)
Is a new condition for turning on the CENB flag. As a result, the free memory can be used up without waste. However, there is a possibility of memory overflow in the middle. In this case, the area control 2 temporarily stops the accumulation in the middle of memory accumulation, restricts the work area to the original data amount (raw image data amount) at that time, that is, the work area end address is accumulated and written to the compressed data. Is rewritten to the image data address when the image overflows, and the compression and accumulation operation of the raw image data up to that point is completed.
[0028]
In this case, when the area control 2 decompresses and transmits data to the next block, the invalid data area is completely whitened. If this is output (printed or displayed), it becomes blank from the middle of a normal document image, and the operator can determine that a memory overflow, that is, an accumulation error has occurred. Alternatively, the polarity of the decompressed (decoded) image data of the valid data portion is inverted and transferred. If this is output, black-and-white reversal occurs in the middle of a normal document image, so that the operator can determine that a memory overflow, that is, an accumulation error has occurred. In addition, addition of information representing an image error, for example, insertion of “ERROR” into the error area may be performed.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an outline of the configuration of an embodiment of the present invention.
2 is a process (1) to (6) in which image data in the work area 1w set on the DRAM 1 shown in FIG. 1 is compression-encoded and written in the storage area 1a, and the compressed data in the storage area 1a is decompressed and decoded. It is a block diagram which shows the process (7)-(12) which is converted and written in word query 1w.
FIG. 3 is a block diagram showing how data is written to and read from DRAM 1 shown in FIG. 1;
4 is a plan view schematically showing a data write area and a notable address in the first embodiment of the DRAM 1 shown in FIG. 1; FIG.
FIG. 5 is a plan view schematically showing a data write area and a noticeable address when an image of one page is compressed and stored in the storage area 2 of the DRAM 1 shown in FIG . 1;

Claims (5)

Memory with linear address space;
Work area writing means for writing image data into a work area in which a write start address is set to one of the maximum address and the minimum address of the memory space of the memory;
Storage area writing means for writing compressed data of image data read from the work area into a storage area in which a write start address is set to the other of the maximum address and the minimum address;
And end address capable of storing image data of more than one page in the work area, the address already shifted address for storing image data of further one page from accumulated end address of compressed data of the storage area If there is a free space between them, the new one page of image data is written to the work area and the compressed data of the image data is stored in the storage area, and one page of the minimum value is stored in the work area. If the free space runs out between the address that has already been shifted address for storing image data of further one page from accumulated end address of compressed data of the end address and the storage area capable of storing image data, An end address capable of storing one page of image data and the compressed data are stored in the work area. When there is no address space between the first and second addresses, writing of a new page of image data to the work area is not started, and when there is an address space, a new page of image data is written to the work area. Memory means comprising control means for starting writing and storing compressed data of the image data in a storage area. Wherein, the work area by setting the end address capable of storing image data of a plurality of pages, the image data of the further one page from the end address already accumulated compressed data in the storage area and the end address The end address of the work area is sequentially changed so as to be narrowed by an address space capable of storing one page of image data if there is no empty area between the address for storage and the shifted address. 2. The memory device according to 1. Address already shifted address for storing image data of further one page from accumulated end address of compressed data of the end address and the storage area capable of storing image data of one page is the minimum value in the work area When there is no more free space between the end address, there is an address space between the end address that can store one page of image data in the work area and the end address that stores the compressed data, and a new one page If the memory is over after starting to write the image data to the work area, the control means stops writing the image data of the document to the work area and compresses the corresponding page in the storage area. When the data is decoded into image data and output, the invalid area is image data for representing overflow. Memory device according to Motomeko 1 or 2. 4. The memory device according to claim 1, wherein one of the maximum address and the minimum address is a maximum address and the other is a minimum address . The memory device according to any one of claims 1 to 4;
Encoding / decoding means for compressing image data stored in the storage area of the memory device and decoding compressed data read from the storage area into image data; and
An image forming apparatus comprising: an image writing unit configured to form an image represented by image data decoded by the encoding / decoding unit, written to the work area, and read from the work area.

Images