United States Patent [19]
[11] Patent Number:
Easterly et al.
[45]
[54]
4,542,403 9/1985
4,703,306 10/1987
4,829,382 5/1989
AUTOMATIC BRIGHTNESS ALGORITHM
IN A SLIDE TO VIDEO TRANSFER UNIT
[75] Inventors: Robert W. Easterly, Churchville;
4,843,476 6/1989
John R. Fredlund, Rochester, both of
Aug. 6, 1991
Zimmermann et al. .......... .. 358/228
Shor ..................... ..
358/54
Hess et al. ........ ..
..
Fujioka et a1. .................... .. 358/228
Primary Examiner-Joseph A. Orsino
NY.
[73] Assignee:
Date of Patent:
5,038,216
Assistant Examiner-—J ill Jackson
Attorney, Agent, or Firm-David M. Woods
Eastman Kodak Company,
Rochester, NY.
[57]
ABSTRACT
[21] Appl. No.: 341,455
Apr. 20, 1989
[22] Filed:
Int.
Cl.5
.............................................
.. H04N 3/36
[511
US.
Cl.
....................................
..
358/228;
358/54;
[52]
A system for automatically controlling the brightness of
an optical image which is translated into digital signal
samples corresponding to the pixels constituting the
[53]
ples, a device for varying the area of the aperture, a
device for detecting peak values of the samples, and a
device for operating the aperture area varying device
until the percentage of the peak values which are above
a certain peak value is a certain percentage.
image includes a variable area aperture through which
the image is transmitted for digitization into the sam
358/214
Field of'S'é'arch ................. .. 358/213.19, 228, 214,
358/54, 55; 354/400, 402
References Cited
[56]
US PATENT DOCUMENTS
4,037,254
7/1977
4,331,979
5/1982 Bendell
Monahan .......................... i. 358/228
8 Claims, 17 Drawing Sheets
8
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b1 MTATN MAXIM VIDEO DATA VALlE THAT OCClBS IN
:1 TEST MAXIM DATA VALLES TO SEE
VALLES All GREATER THAN ‘240';
111 IF MT, GEPERATE APPROPRIATE 8011811 SIGNAL TO
1mm [ITNTBZLLER T0 1 MENTAL“ WEN APERTLE
A10 FEPEAT PHOCETAE KBITNIPG AT STEP 1171
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scum rm succtssivt cam'
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723
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INIX TNTEFRPT
- US. Patent
Aug. 6, 1991
Sheet 1 of 17
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Sheet 2 of 17
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Sheet 3 of 17
FI 6. 2A
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125
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5,038,216
Sheet 5 of 17
FIG. 2C
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Aug. 6, 1991
Sheet 6 of 17
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US. Patent
Aug. 6, 1991
Sheet 7 of 17
5,038,216
FIG. 3
34°
cm DIFFERENCE
+ Z
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US. Patent
Aug. 6, 1991
Sheet 8 of 17
5,038,216
FIG._ 5A
ELLE-GREEN
come DIFFERENCE PLANE
8-6
FIG. 5
8-6
8-6
5-6
8-5
RED-GREEN
COLOR DIFFERENCE PLANE.
W505
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GREEN coma PLAE
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' US. Patent
Aug. 6, 1991
Sheet 9 of 17
5,038,216
FIG. 5B
VEHTICALLY memoursn
/-s2o
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521
522
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523
(8-6)
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(11-6)
529
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(9-9)
(9-6)
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v1 = venue/w INTERPMTED vALuE
VERTICAL INTEPPGJTIW
US. Patent
Aug. 6, 1991
Sheet 10 of 17
5,038,216
FIG. 5C
MIZONTALLY INTERPMTED
SUE-GREEN PLNE
5%
(8-6)
537 538
534
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VALlE
HORIZONTAL im?smounou
' US. Patent
Aug. 6, 1991
Sheet 13 of 17
5,038,216
FIG. 6C
4
PIXELS
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US. Patent
Aug. 6, 1991
Sheet 14 of 17
'
FIG. 7
5,038,216
ENTER
FIG.
WELD" RESET)
MAIN PROGRAM
r 703
FIG.
7A
109
INITIALIZE MICRO-CMTRMER
7A
SYSTEM:
LOAD LOUHP TABLES AN]
CTEFFICIENTS; AN) EXECUTE
VARITXTS DIAGNOSTICS
7B
1
y 706
76-
APPLY APPROPRIATE comnoL SIGNALS TO
nomn commas TO ROTATE TRAY
mm oesmen POSITION AND THEN nova
suns LOCATED AT THAT POSITION
mm mm PATH
l
.
r 709
UNOERTAKE AUTOMATIC amsmuess OPERATION TO
SET INTENSITY 0F LIGHT some TO AN APPROPRIATE
LEVEL
a) SET LP CTAOR CORRECTION ACCUMOLATOR TCCAT
TO PERFORM MAXIMUM VIDEO DATA VALUE DETERMINATION FUNCTION;
b) OBTAIN MAXIMUM VIDEO DATA VALUE THAT OCCURS IN
VARIOUS PAXELS LOCATED TPROUSHOUT THE IMAGE:
c) TEST MAXIMUM DATA VALUES TO SEE IF 3% OF THESE
VALUES ARE GREATER THAN ‘240';
d) IF NOT. OENERATE APPROPRIATE CONTROL SIGNAL TO
MOTEXT CONTROLLER TO INCREMENTALLY OPEN APERTLRE
AM] REPEAT PROCEDURE BEGINNING AT STEP TO)
I
r 712
551 UP ccA FOR Accmna oussnou
r 757
(SET cmsmmon AND FUNCTION)
LT’
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(R (489) W BLOCKS (F PIXEL VALLES
P
SELECT TEXT SUCCESSIVE COLOR
IRS OR B)
A r723
ENABLE VERTICAL
ImEx 111mm
T
r760
US. Patent
Aug. 6, 1991
Sheet 15 of 17
ENABLE mocx' 10 1mm
r758
L
5741
REAO ACCUNLLATEO VALLE FOR PRESENT BLOCK FROM CCA;
COMPUTE AVERAGE VALUE FOR BLOCK TO YIELD AN
AVERAGE PIXEL VALl-E;
FOR EACH SEPARATE PAXEL. CONPUTE ITS LOCAL AVERAGE VALUE
BY TAKING AVERAGE OF 30 SUCCESSIVE AVERAGE PIXEL
VALLES FOR THE PRESENT BLOCK; AN]
STORE RESLLTING LOCAL AVERAGE VALUE IN SEPARATE LOCATION IN
OATA RAN FOR PRESENT PAXEL AM) COLUI
HAS SECMI
BLOCK OE PIXEL
VALIES IN CLBRENT PAIR
VALUE FOR SECOND
BLOCK IN PAIR
r756
GET ACCUHLATEO
PIXEL VALLES Fm
EXT SCAN LIE
5,038,216
US. Patent
Aug. 6, 1991
Sheet 16 of 17
5,038,216
I
FIG. 70
m [750
*
HAVE ALL
[757 "0
PAIRS OF PIXEL BLOCKS
no NExT PAIR
BEEN AccuNJuTEn av
» 0E IMAGE BLOCKS
60A?
YES
769
I
[775
CONVERT LOCAL AVERAGE VALUES FROM we EXPOSURE DOMAIN INTO PRINTING
DENSITY DOMAIN USING TRANSFORMATION MATRIX. o<, AND CONSTANT VECTOR
°<1I°<I2°<Ia
Pdens
R
j = °<2I°<22°<23 PLOG
°<31°<a2°<3a
1
_
j +
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“34
FOR i = 0 TO 7 Am
i = 0 TO 9
["8
EXECUTE AUTOMATIC COLOR BALANCING ROUTINE 800
TO CALCULATE R. 6.8 OFFSET VALUES IN PRINTING
DENSITY OONAIN. edema). usINs CONVERTED LOCAL
AVERAGES IN PRINTING OENSITY DOMAIN. i.e. Pdens VALUES
1
j-TaI
CONVERT ROB OFFSET VALUES IN DENSITY OOMAIN’TO
IQOOREQPOSABF DOMAIN USING INVERSE TRANSFORMATION
(x- I
OLOG (i) = °<" odensG)
INTO
LOADCCACOLOR
240 BALANCE
VIA SERIAL
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mmVALUES
183“. Am
IN LOG
INSTRUCT
DOMAIN.CCA0w;
TO PERFORM
COLOR OFFSET OPERATION ON INCONING PIXEL vALuEs
ETD
US. Patent
Aug. 6, 1991
Sheet 17 of 17
FIG. 8
5,038,216
AUTOMATIC COLOR
BALANIIM RWTINE
QQD.
ENTER
/. 810
CONVERT EACH DENSITY DOMAIN LOCAL AVERAGE VALLE PQEnJEAéELFROM a 6.9 COLOR
SPACE In A DIFFERENT cm SPACE. i.e. NEUTRAL (NEU).
(GRM) Am ILLUHINANT (ILL):
MAsEMIA
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BRMIJ) = 1am. I). 6(i.i). Bli. 11)
ILLlLi) = f3(R(_i.j). BHJH
f 820
DETERMINE NEUTRAL TRANSFER DENSITY (TDNEU) AS A PRE-DEFINED FUNCTION.
f , OF THE MAXIMUM. MINIMUM AND/0R AVERAGE VALUES OF THE NEUTRAL
ANDBLUELDCALAVEHAGEVALUES(FORi=0T07ANDj=1T08)
l
[- B30
DETERMINE GREEN - MAGENTA TRANSFER DENSITY (GRMTD) AN) ILLMMIMAMI
TRANSFER DENSITY (ILLTD) AS MEIsMIEn AVERAGES 0F PRE-DEFINED FUNCTIONS
0E ALL GREEN-MAGENTA mo ILLuMIMAMI LOCAL AVERAGES:
GRHTD
= MEIsMIEn AVERAGE fIjiGRH 1.1;. ILL 3.1“
ILLTD = NEIGHTED AVERAGE f5 6 RN 1,] . ILL I.)
IPEREi=0f7Amj=0-9
l
f 340
DEIEMMIME RED. GREEN Am BUE OFFSET VALUES odensmm PRINTING
DENSITY DOMAIN AS PME-uEFIMEn FLNCTIONS 0F NEUTRAL. GREEN - MAEEMIA
AN) ILLUHINANT TRANSFER DENSITIES;
Odensl?l = II (NEUTD. GH?D mm)
odens?i) ' f8 lNEUTD. GRMTDA
odenst?l = f9 (Mann. sMMIn. mm)
Am
1
5,038,216
AUTOMATIC BRIGHTNESS ALGORITHM IN A
SLIDE TO VIDEO TRANSFER UNIT
2
shown in a darkened room which, as such, is generally
not conducive to maintaining the attention of the view
ers that are present there. In addition, the need for avail
able projection equipment, including a suitably large
5 screen, tends to limit the location at which slides can be
BACKGROUND OF THE INVENTION
shown.
1. Field of the Invention
In view of the drawbacks associated with photo
This invention relates to apparatus and accompany
graphically generated images, whether through prints
ing methods for use in a ?lm to video transfer system for
achieving automatic color balancing of color photo- 10 or transparencies, the art is increasingly turning to
video as a convenient way of capturing and subse
graphic images for subsequent display on a color moni
tor.
2. Description of the Prior Art
Traditionally, images have been stored and displayed
in optical form. For example, photography is one com
monly used method of capturing and subsequently dis
playing an image. Through photography, an image is
captured through photo-chemical interactions occur
ring in a light ie_r_1sitive medium, e.g. ?lm, whenever that
medium is exposed to light emanating from a desired
scene, with the resulting image being depicted either as
a developed photographic print or as a transparency,
the latter forming a part of what is commonly referred
to as a slide. With either prints or slides, the image is
quently displaying images. Owing to the proliferation of
television and video display terminals as a communica
tion media, viewers over the past several years are be
coming increasingly accustomed to viewing a video
image and generally prefer seeing a video image rather
than an image projected from a slide. Moreover, since
color monitors and video tape recorders are becoming
rather ubiquitous, video images can be easily displayed
at nearly any location. These cassettes are highly trans
portable, relatively inexpensive, can store an extraordi
narily large number of different images, are much less
susceptible to damage than slides and, owing to the
ready transportability of a video cassette player and
?xed by a pattern of color dyes dictated by the color
ation of the captured image that has been captured on
the ?lm. Though photographic processes currently
monitor, can be displayed nearly anywhere. Hence, for
provide very high quality images, photography can be a
somewhat tedious and problematic process, both in
terms of properly exposing a piece of ?lm and in terms
increasing use in educational, training, sales and many
these reasons, video images that have been recorded on
video cassettes are rapidly displacing slides by ?nding
other environments and thereby becoming a preferred
medium of choice.
of correctly developing that ?lm to yield a proper opti 30 Presently, a great body of visual information exists in
cal depiction of the image. Moreover, a ?nite amount of
photographic form, i.e. stored on developed ?lm, either
time is required to transform an exposed piece of ?lm,
on slides, transparencies or other photographic formats.
such as by processing it, into a visible image, such as a
To display this information visually on a monitor, the
transparency, a color negative and/ or a color print.
information needs to be electronically converted into a
In addition, photographic images tend to be clumsy
suitable video form, such as an NTSC (National Televi
to display, particularly to relatively large groups such
sion System Committee) composite video signal or sep
as those that might ?ll a classroom or an auditorium. In
particular, available enlarging equipment limits the size
ofa color print. Moreover, greatly enlarged prints, due
arate red, green and blue (RGB) signals, for use with an
available color monitor. While, at ?rst blush, one would
to their size, are frequently cumbersome to handle.
tronically scanning a photographically produced image
Furthermore, greatly enlarged prints tend to be very
expensive owing to the paper and enlarging equipment
needed to produce the print. For those reasons, trans
parencies are often used in lieu of prints. Transparen
cies, in this case slides, are merely inserted in a desired 45
think that the conversion would simply involve elec
with a video camera and then storing the resulting
video image. Unfortunately, this simplistic technique
produces inadequate results.
Although photography provides an individual with
into a slide projector. The projector successively
projects light through each selected slide onto a suitable
an exceptionally wide latitude in capturing an image,
oftentimes the actual image that is captured on ?lm
(negatives or slides) does not accurately depict an origi
image. While slides, in many instances, provide a far
more convenient way of displaying images than
through prints, slides have various drawbacks that tend
55
t limit their utility.
over- or under-exposure, the type of lighting, i.e. tung
sten, ?uorescent or sunlight, is not appropriate for the
speci?c ?lm being used, or the ?lm is old and as a result
has a reduced sensitivity. Generally, with a photograph
order into a suitable carousel which, in turn, is placed
nal scene. This can occur for any one of various reasons,
screen which is positioned some distance away from the
projector. The distance between the screen and the 50 such as illustratively because the exposure, lens aperture
and/or shutter speed, is incorrect which results in an
projector dictates the size-of the resulting displayed
First, slides are also cumbersome to handle. Slides
must be ?rst be arranged into a desired order before
they are inserted into a carousel. If for some reason the
carousel is mishandled, e.g. dropped, and the slides
separate from the carousel, the slides must again be
placed into the proper order. This is time consuming.
Furthermore, slides are relatively fragile. Inasmuch as
light is projected through a transparency that forms
part of the slide, the slide, though containing a protec
tive frame peripherally situated around the transpar 65
ency, must be carefully handled to prevent scratches or
tears to the transparency which, in turn, would corrupt
the resulting image. In addition, slides are usually
ically recorded image, color balancing is used during a
developing process in an effort to correct most de?cien
cies that reside in the image. Color balancing involves
optically changing the colorationv in an image, as origi
nally captured on ?lm, in a deliberate fashion.
The art has recognized that if a subsequent depiction
of a photographic image on an output media is to be as
faithful a reproduction of an original scene as possible,
then not only must chromatic response differences that
occur between an input media that captured the image
and the output media be removed through color balanc
ing but also de?ciencies, to the extent they are correct
able, that occur in the photographic image itself, must
3
5,038,216
4
film to video transfer system in order to provide a faith
also be corrected as well. For example, teachings along
these lines appear in U.S. Pat. No. 4,500,919 (issued to
ately engraved color separated printing cylinders for
ful reproduction of an original scene. Not only should
this apparatus automatically balance the colors based
upon differences in chromatic response between ?lm
and video but also this apparatus should be able to sub
stantially correct for de?ciencies that occur in a photo
use a gravure printing press or the like to subsequently
graphed image itself.
W. F. Schreiber on Feb. 19, 1985 and henceforth re
ferred to herein as the ‘919 patent) in the context of use
within a color editing system that generates appropri
reproduce a color photographic image. Similar teach
ings appear in U.S. Pat. No. 4,364,084 (issued to T.
Akimoto et al on Dec. 14, 1982 and henceforth referred 10
to herein as the ’084 patent) in conjunction with a sys
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to
provide apparatus and accompanying methods for use
tem for transferring images on developed color ?lm to
in a film to video transfer system that, to the extent
photographic paper.
possible, automatically and properly balances the colors
Therefore, a goal of any ?lm to video transfer system
must be end to end ?delity. Speci?cally, if the system is
to produce a proper video depiction of a scene that has
been photographically captured, then that scene must
be reproduced as sharply and as perfectly as possible in
in an image being transferred from ?lm to video or
generally from any photographic medium (such as illus
tratively slides, negatives or prints) to any electronic
medium or display (such as illustratively a magnetic
memory, a optical memory, a video display, an elec
video form e\7e_n though the underlying photographic
tronic printer, an electronic signal and/or others).
A speci?c object is to provide such apparatus and
image itself may be somewhat defective. Hence, if the
photographic image is defective, the de?ciencies exist
ing therein must be corrected prior to the image being
stored in video form for subsequent display. For that
methods that not only compensate for differences in
chromatic response occurring between ?lm and video
but also corrects for de?ciencies that occur in a photo
graphed image itself.
reason, a ?lm to video transfer system must employ
color balancing.
Unfortunately, color balancing techniques generally
known in the art often provide inadequate.results. Spe
ci?cally, in most instances, color balancing techniques
25
A further speci?c object is to provide such apparatus
and methods that substantially reduces, if not totally
eliminates, the need for operator intervention to achieve
a properly balanced video reproduction of an original
known in the art for use in image transfer systems usu
scene.
ally rely on some form of manual operator intervention
In an exemplary embodiment, these and other objects
are accomplished in accordance with the teachings of
the present invention by a system for transferring a
in order to achieve a suitable color balance. In this
regard, some known color balancing techniques, such as
scanned image from ?lm to video format which: ?rst,
through local averaging, transforms the scanned image
Davis et al on Apr. 15, 1986) and U.S. Pat. No.
4,310,848 (issued to W. D. Carter et al on Jan. 12, 1982), 35 from logarithmic exposure (“log exposure”) RGB color
values into corresponding printing density values, then
rely on displaying a scanned photographed image and
utilizes a printing density based color correction
then requiring an operator to manually adjust the color
that disclosed in U.S. Pat. No. 4,583,186 (issued to R. C.
ation of the displayed image prior to that image being
printed. Other known color balancing techniques, such
as those exempli?ed by the teachings in the ’919 patent,
the ‘084 patent and in U.S. Pat. No. 4,676,628 (issued to
Asbury on June 30, 1987) and U.S. Pat. No. 3,972,066
(issued to Seki et al on July 27, 1976) attempt to ?rst
method to generate a color correction offset value for
each of three primary colors (e.g. red, blue and gree
n-RGB), and ?nally converts the three resulting RGB
color correction offset values from the printing density
domain back to the log exposure domain wherein each
offset value is subsequently used to correct the corre
sponding RGB color values associated with each of the
color balance a scanned photographic image in a pre
determined fashion and display a resulting color bal 45 pixels that collectively forms a subsequent scan of the
same image prior to the conversion of each of the color
anced image on a color monitor to an operator who is
then free to manually change the coloration of any
portion of the image, if necessary and as desired, to
produce a proper depiction of an original scene. Unfor
tunately, in any of these prior art techniques, time is
consumed whenever an operator intervenes to adjust
the color or even to just inspect the image. This, in turn,
balanced RGB pixel values into analog video form.
In accordance with the invention claimed herein, the
system for transferring a scanned image from ?lm to
video format automatically controls the brightness of
the optical image which is ‘translated into digital sam
ples. The system includes a variable area aperture
disadvantageously decreases the throughput of the
through which the image is transmitted for digitization
image transfer system that uses such a color balancing
into the samples, a device for varying the area of the
technique. Since the time available for operator inter 55 aperture, a device for detecting peak values of the sam
ples and a device for operating the aperture area vary
vention is often quite limited, color balance techniques
ing device until the percentage of peak values which are
known in the art have not always yielded satisfactory
above a certain threshold value is a predetermined per
results.
centage.
Hence, while recognizing the need to employ some
In accordance ‘with a preferred embodiment of my
form of color balancing, the art has thusfar failed to 60
invention, local averages are determined for each verti
provide a technique for use in an image transfer system,
cally contiguous 30 line group of 56 horizontally contig
and particularly in a ?lm to video transfer system, that
uous pixels, each such group henceforth referred to as a
automatically and properly color balances an image
“paxel". Speci?cally, a scanned image, such as one
while generally eliminating or, at the very least, sub
stantially reducing the need for operator intervention. 65 having 560 pixels by 240 lines wherein each pixel has
associated digital log exposure RGB color values, is
Therefore, a need currently exists in the art for appa
partitioned into paxels, such as a matrix of 8-by-l0 pax
ratus and accompanying methods for use therein that, to
els. Each paxel has one set of log exposure color (RGB)
the extent possible, automatically balances colors in a