JP2003092686A - Image communication apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image communication apparatus capable of preventing image quality deterioration due to re-encoding in memory transmission. SOLUTION: The image communication apparatus is characterized in to comprise a first encoding means for encoding image data obtained by reading an original by means of a first encoding system being the lossless encoding system to generate first encoded image data, a second encoding means for encoding the image data obtained by reading the original or the image data decoded by the first encoding means by means of a 2nd encoding system being a lossy encoding system to generate second encoded image data, an image data storage means for storing the 1st encoded image data, and an image data communication means for transmitting the second encoded image data to a receiver side apparatus.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image communication apparatus, and more particularly, to image data obtained by reading an original document.
First encoding means for generating the first encoded image data by encoding with the encoding method of 1) and decoding the first encoded image data; and image data obtained by reading the original document, or Second encoding means for generating second encoded image data by encoding the image data decoded by the first encoding means by a second encoding method; and the first encoded image data. The present invention relates to an image communication apparatus including image data storage means for storing and accumulating and image data communication means for transmitting the second encoded image data to a receiving side device.

[0002]

2. Description of the Related Art In the ITU-T standard of color facsimile, it is recommended to communicate by JPEG (CIELAB) of color multi-valued data.

On the other hand, since the color multi-valued data has a large amount of data, it is required to reduce the amount of transmitted data.

In the technique disclosed in Japanese Patent Laid-Open No. 2000-59597, the amount of transmission data is reduced by JBIG encoding of color binary data, and it can be applied only to a communication device that is out of the ITU-T standard. If the output characteristics of the receiving side device are unknown, the image quality cannot be maintained because proper color binarization processing cannot be performed.

When a coding / decoding process such as coding, decoding and re-coding is repeatedly performed by a lossy coding system such as lossy JPEG which is a standard coding system of color facsimile ITU-T, image quality is deteriorated. Occur.

[0006]

Therefore, in the case of direct transmission of a color facsimile, that is, when the original image data is read and encoded and transmitted in real time, the encoding is performed only once, but the memory transmission, that is, In many cases, it is necessary to read the original image data, encode it to reduce the required storage capacity, store it in the memory once, and then re-decode / encode it at the time of transmission using the encoding method that is compatible with the receiving device. There is a problem in that the image quality of the memory transmission image may be inferior to that of the direct transmission image due to image quality deterioration due to recompression.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an image communication apparatus capable of preventing deterioration of image quality due to re-encoding when performing memory transmission.

[0008]

According to a first aspect of the present invention, there is provided an image communication apparatus, wherein first image data obtained by reading a document is read.
First encoding means for generating the first encoded image data by encoding with the encoding method of 1) and decoding the first encoded image data; and image data obtained by reading the original document, or Second encoding means for generating second encoded image data by encoding the image data decoded by the first encoding means by a second encoding method; and the first encoded image data. An image communication apparatus comprising image data storage means for storing and accumulating, and image data communication means for transmitting the second encoded image data to a receiving side apparatus, wherein the first encoding means comprises the first encoding means. The first coding method is a lossless coding method, while the second coding method in the second coding means is a lossy coding method.

According to another aspect of the image communication apparatus of the present invention, the image data obtained by reading the original is encoded by the first encoding method to generate the first encoded image data while the first encoding is performed. First encoding means for decoding image data,
The image data obtained by reading the original document or the image data decoded by the first encoding means is used as the second image data.
Second encoding means for generating the second encoded image data by encoding with the above encoding method, image data storage means for storing and accumulating the first encoded image data, and the second encoded image. An image communication apparatus comprising image data communication means for transmitting data to a receiving side apparatus, wherein encoding by the first encoding method in the first encoding means is image quality priority setting lossy code. While the encoding is performed by the encoding method, the encoding by the second encoding method in the second encoding means is performed by the lossy encoding method of the compression rate priority setting.

An image communication apparatus according to a third aspect is the image communication apparatus according to any one of the first and second aspects,
The second encoding method in the second encoding means is
It is characterized by the JPEG system, which is the standard for color facsimiles.

An image communication apparatus according to a fourth aspect is the image communication apparatus according to any one of the first and second aspects,
The first encoding unit and the second encoding unit are configured to use one encoding circuit in a time division manner.

An image communication apparatus according to claim 5 is the image communication apparatus according to any one of claims 1 and 2.
The encoding in the first encoding means is performed by the first encoding method that does not depend on the image quality mode setting, while the encoding in the second encoding means is performed by the second encoding according to the image quality mode setting. It is characterized in that it is carried out by a system.

[0013]

DETAILED DESCRIPTION OF THE INVENTION Referring to the accompanying drawings,
Embodiments of the present invention will be described in detail.

First, FIG. 1 shows a block configuration of an image communication apparatus 1 according to an embodiment of the present invention.

In FIG. 1, a scanner unit 2 and a color image sensor are provided to read a document and output analog image data data. The A / D conversion unit 3 converts the analog image data from the scanner unit 2 into color multivalued digital image data. Video correction unit 4
Is for performing shading correction on color multi-valued digital image data obtained by the A / D conversion unit 3 to correct white waveform distortion in the scanner unit 2. The image quality processing section 5 performs desired image processing such as filter calculation on color multi-level digital image data data. The resolution conversion unit 6 converts the resolution of color multi-value digital image data. The color space conversion unit 7 uses the RG
The color spaces such as B and CIELAB are mutually converted. The first encoding unit 8 as the first encoding means encodes / decodes color multi-level digital image data data by the first encoding method. The second encoding unit 9 as the second encoding means encodes / decodes the color multi-level digital image data by the second encoding method. The storage unit 10 serving as image data storage means temporarily stores image data, and includes a memory and a hard disk. The communication unit 11 as an image data communication unit transmits / receives encoded color multi-level digital image data. The operation display unit 12 receives various operation inputs and performs various displays such as a device operation status display. The system control unit 13 is a microcomputer that controls each unit of the device, and includes a CPU and R
It is composed of OM, RAM and the like.

Next, an image data transmission processing procedure in the image communication apparatus 1 will be described with reference to FIG.

The transmission process shown in the figure relates to so-called memory transmission, in which the read image data is stored and then transmitted. First, the scanner unit 2 reads an original and outputs analog image data ( Processing 10
1), the A / D converter 3 converts the analog image data into color multi-level digital image data (process 102), the video corrector 34 performs shading correction (process 103), and the image quality processor 5 Then, the edge enhancement is performed by the filter calculation (process 104), and the color space conversion unit 6 performs RG.
B is converted to CIELAB (process 105), CIELAB data is encoded by the first encoding unit 8 using the first encoding method (process 106), and the first encoded image data is stored and stored in the storage unit 10. The process is repeated until the reading of the document is completed (No loop of decision 108). When the reading of the document is completed (Yes of decision 108), the process is temporarily saved in the storage unit 10 at step 107. The first encoded image data, which has been
The image data obtained by decoding (processing 109) in step S1 is converted by the resolution conversion part 6 into the resolution set with the receiving side device of the transmission destination (step 110), and the second encoding part 9
Then, the encoded image data obtained by encoding with the second encoding method set with the receiving side device of the transmission destination (process 111) is transmitted to the receiving side device of the transmission destination by the communication unit 11. Then, a process for transmitting is performed (process 112).

Specific steps of the first encoding process by the first encoding unit 8 of the process 106 and the second encoding process of the process 111 are shown in FIG. 3, FIG. 4, and FIG.
Alternatively, any of the procedures shown in FIG. 6 can be applied.

In the procedure shown in FIG. 3, lossless J is used as the first encoding process by the first encoding unit 8 of the process 106.
It is encoded by a lossless encoding method such as PEG (Processing 2
01) On the other hand, as the second encoding processing in the processing 111, encoding is performed by the lossy encoding method such as baseline JPEG (processing 301).

In the procedure shown in FIG. 4, as the first encoding process by the first encoding unit 8 of the process 106, the parameters such as the quantization matrix are encoded with the image quality priority setting in the lossless encoding method such as the baseline JPEG. (Process 4
01) On the other hand, as the second encoding process in process 111, parameters such as the quantization matrix are encoded by the lossy encoding method such as baseline JPEG with compression ratio prioritized (process 501).

In the procedure shown in FIG. 5, as the second encoding processing in the processing 111, encoding is performed by the baseline JPEG (CIELAB) system which is the standard of color facsimile (processing 601).

In the procedure shown in FIG. 6, in the color facsimile, since many devices can select the image quality to be transmitted by the image quality selection switch, the image quality mode setting is performed as the first encoding process by the first encoding unit 8 of process 106. I don't care first
On the other hand, the encoding is performed by the encoding method (process 701). On the other hand, as the second encoding process in process 111, when the image quality mode is "standard", parameter setting is performed so that the compression rate is high, and the image quality mode is "fine". In this case, the compression rate is slightly inferior, but the parameters are set so that the image quality can be maintained, and then the second encoding method is used for encoding (process 801).

Further, as the first encoding unit 8 and the second encoding unit 9, the encoding process in each of the first encoding system and the second encoding system is performed by one encoding circuit in a line or block. By performing the switching operation in units, the device configuration can be simplified.

As described above, according to the present embodiment, it is possible to eliminate or minimize the deterioration of the image quality caused by the encoding / decoding of the image data during the memory transmission and the re-encoding. it can.

[0025]

According to the invention of claim 1, the second
Even if the encoding in the encoding means is the lossy encoding method accompanied by the image quality deterioration, the encoding / decoding in the first encoding means is performed by the lossless encoding method. Therefore, the first encoding The image quality deterioration in the case of so-called memory transmission, in which the document image data is encoded by the means, temporarily stored and accumulated in the image data storage means, read and decoded, re-encoded and transmitted by the second encoding means, The effect that can be prevented is obtained.

According to the second aspect of the present invention, even if the coding in the second coding means is a lossy coding method of compression ratio priority setting in which image quality deterioration is relatively large, the first coding means is used. Since the encoding / decoding in step 1 is performed by the lossy encoding method of image quality priority setting in which the image quality deterioration is relatively small, the original image data is encoded by the first encoding means and is temporarily stored in the image data storage means. After storing and accumulating, reading and decoding, re-encoding by the second encoding means and transmitting, that is, so-called memory transmission, it is possible to minimize deterioration of image quality.

According to the third aspect of the present invention, the second encoding method in the second encoding means conforms to the JPEG method, which is a standard for color facsimiles. It is possible to obtain the effect that the present invention according to item 1 or item 2 can be applied.

According to the fourth aspect of the present invention, since the encoding circuit is constructed by one, there is an effect that it is possible to suppress the cost increase of the device.

According to the invention of claim 5, the same effect as that of the invention of claim 1 or 2 can be obtained regardless of the image quality mode.

[Brief description of drawings]

FIG. 1 is a diagram showing a block configuration of an image communication apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart showing an image data transmission processing procedure in the image communication apparatus according to the embodiment of the present invention.

FIG. 3 is a flowchart showing a specific processing procedure of each of a first encoding process and a second encoding process.

FIG. 4 is a flowchart different from FIG. 3 showing a specific processing procedure of each of the first encoding processing and the second encoding processing.

FIG. 5 is a flowchart different from FIGS. 3 and 4 showing a specific processing procedure of second encoding processing.

FIG. 6 is a flowchart different from FIG. 3, FIG. 4 or FIG. 5 showing a specific processing procedure of each of the first encoding processing and the second encoding processing.

[Explanation of symbols]

1 Image communication device 2 Scanner section 3 A / D converter 4 Video correction section 5 Image quality processor 6 Resolution converter 7 Color space converter 8 First code part 9 Second code part 10 memory 11 Communications Department 12 Operation display section 13 System control unit

Continued front page    F term (reference) 5C059 KK01 KK41 LA01 PP01 PP14                       PP22 RA01 RE15 RE16 SS06                       TA17 TA68 TC38 UA02 UA32                       UA38                 5C078 AA04 AA09 BA57 CA12 DA01                       DA02 DB01 DB11                 5J064 AA01 BC01 BC02 BC06 BD02

Claims (5)

[Claims] 1. A first code for encoding image data obtained by reading an original by a first encoding method to generate first encoded image data, and for decoding the first encoded image data. Encoding means and image data obtained by reading the document, or image data decoded by the first encoding means is encoded by a second encoding method to generate second encoded image data. The second encoding means, the image data storage means for storing and accumulating the first encoded image data, and the image data communication means for transmitting the second encoded image data to the receiving side device are provided. An image communication apparatus, wherein the first encoding method in the first encoding means is
An image communication apparatus, wherein the second coding method in the second coding means is a lossy coding method while being a lossless coding method. 2. A first code for encoding image data obtained by reading an original by a first encoding method to generate first encoded image data, and for decoding the first encoded image data. Encoding means and image data obtained by reading the document, or image data decoded by the first encoding means is encoded by a second encoding method to generate second encoded image data. The second encoding means, the image data storage means for storing and accumulating the first encoded image data, and the image data communication means for transmitting the second encoded image data to the receiving side device are provided. In the image communication device, the encoding by the first encoding method in the first encoding means is performed by a lossy encoding method of image quality priority setting, while the second code by the second encoding means is performed. System Coding, image communication apparatus and performs the lossy coding scheme compression ratio preferences by. 3. The second encoding method in the second encoding means is JPE which is a standard for color facsimile.
The image communication apparatus according to claim 1, wherein the image communication apparatus is a G system. 4. The first encoding means and the second encoding means are configured to use one encoding circuit in a time division manner, according to claim 1 or 2. Image communication device. 5. The encoding in the first encoding means is
The first encoding method that does not depend on the image quality mode setting is performed, while the encoding in the second encoding means is performed by the second encoding method that corresponds to the image quality mode setting. The image communication device according to any one of 1 or 2.