Apparatus and methods for locating edges and document boundaries in video scan lines

72 Pages·2013·4.32 MB·English

United States Patent [191
[11] Patent Number: 4,833,722
Morton et al. [45] Date of Patent: Ma 23 1989
7
[54] APPARATUS AND METHODS FOR 4,672,461 6/1987 Yoshida ............................. .. 358/280
_ LOCATING EDGES AND DOCUMENT 4,774,569 9/1988 Morton et a1. ...................... .. 382/22
BOUNDARIES IN VIDEO SCAN LINES Primary Examiner-Leo H. Boudreau
[75] Inventors: Roger R. A. Morton; John E. Redden, Assistant Examiner-Jose L- Couso
both of Rochester, NY‘ Attorney, Agent, or Firm—-Dennis R. Arndt
[73] Assignee: Eastman Kodak Company, [57] ABSTRACT
Rochester’ N-Y- Apparatus, and accompanying methods for use therein,
[21] APPL NO; 77,527 for locating edges contained within each scan line of a
_ scanned video image and also for locating horizontal
[22] Fll?d: Jul‘ 24’ 1987 boundaries (leading and trailing edges) of a portion of a
[51] Int. Cl.4 ............................................. .. G06K 9/48 document contained within the scan line are described
[52] US. Cl. ...................................... .. 382/ 22; 382/23; herein. Speci?cally, this apparatus ?rst provides a back
Y 358/282 ground value representative of a background level in a
[58] Field of Search ..................... .. 382/22, 23, 50, 25, scanned ima g e and associated with an incomin g P ixel
382/ 52-54, 56; 355/64; 358/282 value. If the background value exceeds a ?rst reference
[56] References Cited value, a ?rst signal is generated. If the incoming pixel
value exceeds a second reference value, a second signal
U-S' PATENT DOCUMENTS is generated. Now, an edge transition is detected based
4,053,928 10/1977 Orton et al. 358/96 upon a pre-de?ned logical combination of the ?rst and
4,115,805 9/1978 Morton .... .. . 382/23 second signals. If such a transition has been detected,
4,115,305 9/1973 M0110“ -- 382/23 such as a leading or trailing edge in either the incoming
Egan: pixel values or in the background level, a control cir
4’399’ 461 8/1983 Poi/e1? ‘ “““ "358/166 cuit, illustratively implemented using a programmed
4:451:854 5/1985 Daigo __ 358/282 array logic circuit and various counters, determines if
4,499,593 2/19g5 chittineni _____ “ 332/54 the edge transition is associated with valid leading or
4,501,016 2/ 1985 Persoon et al. 382/22 trailin 8 edge, i.e. wheter the transition itself is followed
4,553,260 11/1985 Belt 9t 81
332/22 by a pre-determined number of similar pixel values. If a
12/ gang“ ~ - ~ ~ ~ - ~ - - -' 222/213 valid leading or trailing edge is detected, then the con
4:575:751 3/1986 niiiciiiani. . . . . . . . ' i SSS/T66 tml. circuit generates appmpriate signals. t° St°re the
4,577,235 3/1986 Kannapen at a]. _ 58/280 horizontal pixel address of the incormng pixel value as a
4,578,765 3/ 1986 Barker ,,,,,,,,,, ._ 364/514 leadlng or trailing edge. In addition, once all the leading
4,590,606 5/1986 Rohrer 358/282 and trailing edes have been determined for a current
4,611,349 9/ 1986 Hon ....... .. 382/47 scan line, then the leading/trailing edge pair having the
4,613,990 10/1936 51F‘) 9* al- 382/ 43 widest spacing is selected as being the designated lead
g‘ggtm: ing and trailing edges (horizontal boundaries) of a por
4’636’863 V1987 Kaeisza?i ct a'l' 358/167 tion of a scanned document located within the current
4,637,059 1/1987 Habitzreiter et al. 382/54 Scan lme'
4,638,369 l/l987 Hsieh ............ .. . 358/283
4,648,120 3/ 1987 Chittineni ............................ .. 382/54 33 Claims, 42 Drawing Sheets
CENTE lxPnIXi i [447 E CENTER PIXEL VALUE
BACKGROUND 1474 B BACKRUUND VALUE
TRACKER UUTPUT
{- """"" —_EIF5E'TFET """"" 'E?? _______ "2T1 """" "-1. s1 7
i 4675 CUTOFF OFFSET 5103 H H 1‘ BAC??g?D >
i DATA BUS pm REGISTER a" 3 ml SUBTHACTEFT no LATCH gMs'uE :' ;. COMPARATOR ‘)5 CUTUFF
C m 2 H I 5139
i A B 5113 l
I CONTROL SIGNALS 8 |
i CUTUFF ADJUST : /~513o 5141
| REGISTER 57127 ‘1’ 9. VIDEO >
: 4675 IN, I f A CUTOFF
| DATA Bus E\::>3INADD REGISTER no 1112 ALU no 8 LATCH I COMPARATOR M,
; "10E co : 5143
]! "DB1 515 5159' ! BACKGROUND >
I 48‘7‘5‘ 4875 I CUTQFF
! DATA BUS DATA BUS
I Am, 5147
i 1 0
1__-__-__ _ _______________ __ ___°_“T_°f§l"_L‘!E_5E'iEPl“§_°L°9F_i\5‘° 5155,
5157,
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