AIIM TR17-1989 Facsimile and Its Role in Electronic Imaging《传真电子成像中的作用》.pdf

1、m a m Y- Bandwidth compression. A technique to reduce the band- width needed to transmit a given amount of facsimile information in a given time or to reduce the time needed to transmit a given amount of facsimile information in a given bandwidth. Baud. The number of changes in signai state per seco

2、nd in a digital signal sent by a modem. A baud may contain four or more bits as in a CCIT V.29 modem. Bit. The contraction for binary digit, the smallest amount Color facsimile system. A facsimile system which produces the recorded copy in more than one color. Typically, a full color image is produc

3、ed by sending images for three primary colors. Compatibility. Matching facsimile transmitter and facsimile receiver characteristics which permits acceptable facsimile copy to be received. Compression ratio. In digital facsimile, the ratio of the total bits used to represent the original to the total

4、 number of en- coded bits. Continuous tone image (analog gray scale image). An image in which each resolvable element may be represented by one of a continuous range of tones. Contouring. Density step lines in recorded copy resulting from quantization of an original image which has observable gray s

5、hadings between adjacent quantization intervals. Digital facsimile. That form of facsimile in which densities of the original are sampled and quantized as a digital signal for processing, transmission, or storage. Direct recording. That type of facsimile in which a visible recorded copy is produced

6、without subsequent processing. Document. A set of one or more pages which can be transmitted as a unit. Electrolytic recording. Recording with signal-controlled cur- rent through an electrolyte in the recording paper, depositing metallic ions to produce a mark. Electronic shading. An electronic meth

7、od of compensating for variations in sensitivity of individual sensors of a sensor array or variation in illumination of copy being scanned. This may be done by correcting the analog signai from each sen- sor sample under control of stored digital information. Electrosensitive recording. Recording w

8、ith an electrical signal which passes directly into the record medium. Electrostatic recording. Recording by means of a signai con- trolled electrostatic field. NOTE: A toner is required to make the image visible. 1 AIIM TRI7 89 IOL23qB 0000b7b 2 End-of-line (EOL). In Group 3 digital facsimile syste

9、ms, a sequence of digital symbols introduced at the end of a scan- ning line to establish synchronization of decoding and for error detection. Facsuiiile. The process by which a document is scanned, con- verted into the electrical signals, transmitted, and recorded or displayed as a copy of the orig

10、inal. Fade copy. A recorded copy of an original produced by a facsimile recorder. Facsimile receiver. The apparatus employed to translate pic- ture signals from the communications channel into a fac- simile copy of the original. Facsimile recorder. That part of the facsimile receiver which performs

11、the final conversion of electrical picture signals to an image of the original on the record medium. Facsimile signal. See picture signal. Facsimile transmitter. The apparatus used to translate the original into picture signals suitable for delivery to the com- munication system. Fax. An abbreviatio

12、n for facsimile. Fingerprint facsimile. Facsimile equipment used to transmit fingerprint cards. Nom Existing systems send 8 inch x 8 inch cards at 192 lines per inch. Ghost. In analog facsimile, a spurious image resulting from echo, envelope delay distortion, or multipath reception. Group 1. Analog

13、facsimile equipment per CCIIT Recom- mendation T.2. (Sends an A4 or 8.5 x 11 inch page in six minutes over a voice grade telephone line using frequency modulation with 1,300 hertz corresponding white and 2,100 hertz to black of the original.) Note: Since North American six minute equipments use 1,50

14、0 hertz white and 2,400 hertz black, they are not compatible with Group 1 equipments. Group 2. Analog facsimile equipment per CCITT Recom- mendation T.3. (Sends an A4 or 8.5 x 11 inch page in three minutes over a voice grade telephone line using 2,100 hertz Ah4-PM-VSB.) Group 3. Digital facsimile eq

15、uipment per CCIIT Recom- mendation T.4. (Sends an A4 or 8.5 x 11 inch page typical- ly in a half minute over a voice grade telephone line,) Group 4. Digital facsimile equipment per CCITT Recom- mendations T.5 and T.6. (Uses public data networks and their procedures for essentially error-free recepti

16、on. May also be used on the public switched telephone network with an appropriate modulation process.) Halftone image. An image that has been converted from a continuous tone image into a two tone image while retain- ing the appearance of a continuous tone image. Handshaking. An exchange of signals

17、(calied control pro- cedures) between the facsimile transmitter and facsimile receiver to verify that facsimile transmission can proceed, to determine which specifications wiU be used and to verify reception of the documents sent. Horizontal resolution. The number of picture elements per inch (or mm

18、) in the direction of scanning or recording. Jitter (in facsimile). Irregular error in the position of the recorded spot along the recorded line. NOTE: This is noticeable on the recording of a vertical line. K factor (in modified read coding for Group 3 facsimile). The number of facsimile scanning l

19、ines in a set used for coding. At the most, K minus 1 lines are coded two- dimensionally to iimit the disturbed area in the event of transmission errors. In CCITT Group 3, K=2 for 3.85 lines/mm and K=4 for 7.7 lines/mm. In Group 4, K = infinity. Lines Per Inch (or mm). The number of scanning or reco

20、rd- ing lines per unit length measured perpendicular to the direc- tion of scanning. Line-fo-line correlation. The correlation of image informa- tion from scanning line to scanning line. Useful for two- dimensional coding, e.g. modified read. Maximum keying frequency. The frequency equal to one- hal

21、f the nhmber of picture elements per second. Mobile facsimile. Facsimile equipment used within vehicles for facsimile. Modified Huffman (MH) coding. A one-dimensional run length digital scheme of coding white and black runs where the shortest length code words represent the most probable run lengths

22、. Used by Group 3 facsimile. Modified read (MR) coding. A two-dimensional optional digital coding scheme for Group 3 facsimile. NOTE: MR provides an improved transmission speed over modified Huffman coding. Newsphoto facsimile. Facsimile equipment used to transmit photographs for newspaper or magazi

23、ne publishing. Original. A page which is transmitted by facsimile. Pel. A picture element that contains only black-white infor- mation (no gray shading). See pixel. Photographic recording. Recording by the exposure of a photosensitive surface to a signaiantrolid light beam or spot. 2 AIIM TR17 89 W

24、1012348 0000677 4 W Picture element. The smallest area of the original which is sampled and represented by an electrical signal. See pel and pixel. Picture signal. A signal resulting from the scanning process or an electronically generated equivalent. Pixel. A picture element that has more than two

25、levels of gray scale information. See pel. Pixel interpolation. Generation of additional unscanned pixels by logical comparison of nearby scanned pixels to simulate increased resolution. Interpolation may be one or two dimensional. Quantizing levels. In a digital facsimile system the number of diffe

26、rent gray steps representing a continuous tone image. See contouring. Record medium. The physical medium on which the fac- simile recorder forms an image of the original. Record sheet. The medium used to produce the recorded copy. The record medium and the record sheet may be identical. Recorded cop

27、y. A hard copy of the original produced by facsimile. Recording. The process of converting the picture signal in a facsimile receiver to an image on the record medium. Recording spot. The image area corresponding to a picture element formed at the record medium by the, facsimile recorder. Redundancy

28、 reduction. Coding for elimination of redundant information in the picture signal to reduce the amount of information needed for transmission or storage. NOTE: The amount of redundancy reduction will vary with the information content of the original. See compression ratio. Resolution. A measure of c

29、apability to delineate picture detail. Scanner. That part of the facsimile transmitter which systematically translates the densities of the original into a signal-wave form. Scanning. The process of analyzing successively the densities of the original according to a predetermined pattern. Scanning d

30、irection, Normal direction is from left to right and top to bottom of the original as when reading a page of print. Scanning line length. See total line length. Scanning spot. The area on the original viewed instantane- ously by the photosensor of the scanner. Skew. 1. The deviation of the recorded

31、copy from rectan- gularity due to asynchronism between scanner and recorder. 2. Angular misalignment of the original from the paper feed direction. 3. Deviation of the angle of the scanning line or recording line from a perpendicular to the paper path. Soft copy. That form of facsimile which display

32、s the received image on a cathode ray tube or similar display. Subject copy. See original. Synchronizing. The maintenance of the proper position of the recording spot while it is writing to produce an undis- torted recorded copy of the original. Themai recording. That type of recording which is prod

33、uced principally by signal-controlled thermal action. NOTE: Direct thermal recording involves direct imaghg on the record medium. Thermal transfer recording involves heat from a thermal print head transferring marking from a car- bon ribbon or overlay sheet to another sheet, forming the recorded cop

34、y. Some recorders produce full color recordings by successively overwriting different colors in the same area. Totai line length VLL). In digital facsimile, the FL is equal to the pels per scan line divided by the pels per mm. Transmission time. The time for sending a single page (elapsed time betwe

35、en the start of picture signals and the detection of end-of-message signal by the facsimile receiver). Xerographic recording. Recording by action of a light spot on an electrically charged photo-conductive insulating sur- face where the latent image is subsequently developed with a toner. 1.3 CCIT S

36、tandards for Office Facsimile Standards for office type fax started in October 1966 with RS-328, generated by Committee TR-29 on Facsimile Equip- ment and Systems of the Electronics Industry Association IA). This standard is obsolete and TR-29 now represents the U.S. through the State Department in

37、CCIT (Interna- tional Telegraph and Telephone Consultative Committee) activities on facsimile. The CCITT completed standards for Group 1 fax in 1968, Group 2 in 1976, Group 3 in 1980, and Group 4 in 1984. These standards are updated every four years after issuance to correspond with the four year CC

38、ITT cycle. The CCITT, part of the International Telecommunica- tions Union of the United Nations, developed the following recommendations, effectively standards, for office-type fac- simile units (see Table 1). 3 AIIM TRI7 89 W Loi12348 OOOOb78 b W ;roup 1 2 3 1,2,3 - 4 4 4 4 4 4 4 4 4 4 4 4 4 Recom

39、mendation T.2 T.3 T.4 T.30 Standardization of Group 1 Facsimile Apparatus for Document Transmission Standardization of Group 2 Facsimile Apparatus for Document Transmission Standardization of Group 3 Facsimile Apparatus for Document Transmission Procedures for Document Facsimile Transmissions for th

40、e General Switched Telephone Network NOTE: The general switched telephone network is usualy referred to as the public switched telephone network o. It is the regular telephone network, once called DDD. T.563 Terminal Characteristics for Group 4 Facsimile Apparatus T.503 Document Application Profile

41、for Interchange of G4 Documents T.521 Communication Profile for BTO Bulk Document Transfer Under T.62 Session Service Environment T.6 Facsimile Coding Schemes and Coding Control Functions for Group 4 Facsimile Apparatus T.62 Control Procedures for Teletex and Group 4 Facsimile Services T.70 Network

42、Independent Basic Transport Services for the Telematic Services T.72 Terminal Capabilities for Mixed Mode Operation E.5 is replaced by these T.500 series recommendations m.73 was replaced by the foiowing T.400 Series-Recommendations for Document Transfer, Access, and Manipulation TAM), Office Docume

43、nt Architecture (ODA), and Interchange Format T.411 Introduction American Libraries, January, 1988, pg. 60. 13 I AIIM TRI7 89 LO12348 0000b88 9 Table 3. Features of Group 3 Fax Machines PRICE CLASS 12345 n f smm aaaaa nfmaa nfmaa aaaaa fmaaa maaaa f mmmm nf fmm nnff* nfmaa fmaaa FEATURE Alternate nu

44、mber calling. The document may be sent to an alternate fax machine if the fax machine originally called is in use. Automatic background control (ABC). When sending a page, the same results are obtained for gray or colored backgrounds as for white. The ABC circuit adjusts the background signal level

45、to be the same as white before digitizing it to black/white. This saves the operator from trying to guess the proper setting: Automatic cutter. This very desirable feature cuts the received pages and stacks them in the receive tray. Without a cutter, a long banner of paper spills on the floor if doc

46、uments are received while the fax machine is unattended. The time saved can easily pay for the extra cost. If, however, the fax pageis torn off for immediate use as received, a cutter is probably not needed. Automatic dialing. The phone numbers of fax machines frequently called can be stored in memo

47、ry and used for sending fax transmissions by pressing one or two buttons. Automatic disconnection. The fax machine automatically disconnects from the phone line after the last page is sent or after a page sent is not received properly. This keeps the fax line open when the fax is not in use. Automat

48、ic document feeder (ADF). A tray is provided to hold and automatically feed the documents to be sent. It is not necessary to hand feed one page at a time or to wait at the fax machine while the pages are sent. Five page capacity is common on very small fax machines, and 30 pages on full size fax mac

49、hines. Automatic reception. The Group 3 fax machine can be left with power always on, ready to receive documents 24 hours a day. Automatic redial. If the called fax machine is busy, it is called again in five or ten minutes. Automatic retransmission. Pages not received successfully can be automatically resent from memory. Book scanning mode. This feature allows a book to be placed on the glass plate top of the fax machine and scanned. Broadcasting. Documents stored in memory can be sent sequentially to many different loca- tions. Delayed sending can be set up to use lower night tele