null User manual

null  User manual
US005969754A
United States Patent [19]
[11]
Patent Number:
Zeman
[45]
Date of Patent:
[54]
CONTRAST ENHANCING ILLUMINATOR
5,969,754
Oct. 19, 1999
In Focus Systems, LitePro 620, http://WWW. infocus.com/
products/projectors/lp620.html.
[76]
Inventor:
Herbert D. Zeman, 1687 Peach Ave.,
Memphis, Tenn. 38112
Texas Instruments, Digital Micromirror Device, http://WW
W.ti.com/dlp/docs/papers/state/state.htm.
[21] Appl. No.: 08/762,599
[22]
Filed:
Dec. 9, 1996
Primary Examiner—Wendy Garber
[51]
Int. Cl.6 .......................... .. H04N 7/18; H04N 5/208;
[52]
US. Cl. .......................... .. 348/136; 348/61; 348/252;
H04N 5/225
348/342; 348/370; 382/274
[58]
Assistant Examiner—Ngoc-Yen Vu
Attorney, Agent, or Firm—Luedeka, Neely & Graham, PC
[57]
ABSTRACT
Field Of Search ................................... .. 348/207, 252,
An apparatus Which enhances the visual contrast betWeen
348/625, 744, 62, 63, 79, 136, 584, 335,
340, 342, 343, 344, 164, 370; 382/266,
274; 359/634; H04N 7/18, 5/208, 5/222,
bright and dark features of an object by projecting an image
of the object onto the object. The features of the projected
object image overlay the features of the object such that an
observer of the enhanced object senses that the bright
5/225
[56]
features are brighter and the dark features remain the same.
References Cited
A light source illuminates the object, a video imaging
U.S. PATENT DOCUMENTS
3,017,515
3,849,910
means, such as a video camera, creates a video signal
1/1962 Welch ................................ .. 250/2081
11/1974
Greenly
........
. . . . ..
434/22
4,065,788 12/1977 Meier et a1.
4,502,075 2/1985 De Forest et a1.
348/625
348/79
4,591,918
5/1986
Hisano ........... ..
348/343
4,740,812
4/1988
Pryor
4,908,876
3/1990 DeForest et a1.
5,041,965
8/1991
.. ... ... ... ... ..
Chen .................. ..
. . . . ..
355/77
382/54
364/200
5,220,624
6/1993 Sakamoto et a1.
382/266
5,231,434
7/1993 Kennedy et a1.
353/122
5,239,373
8/1993 Tang et a1.
5,353,075 10/1994 Conner et a1.
5,359,550
10/1994
5,424,838
6/1995
Chen .......... ..
.. 348/14
353/122
. 364/7081
Siu ........................................ .. 356/394
representative of the object image, and a video projector
receives the video signal from the video camera and projects
a visual image of the object. A?lter prevents video projector
light from reaching the video imaging means, thereby elimi
nating positive feedback. A preferred apparatus includes a
beam separator Which causes the image projected from the
video projector to illuminate the object from the same
perspective that the video imaging means vieWs the object.
Preferably, the light source is an infrared light source, the
?lter transmits infrared light but not visible light, and the
beam separator re?ects visible light and transmits infrared
light. Alternately, the invention visually enhances the edges
of features of an object With an unsharp masking edge
OTHER PUBLICATIONS
Peli et al., Image Enhancement for the Visually Impaired,
Investigative Ophthalmology & Wsual Science, vol. 32, No.
8, Jul. 1991, pp. 2337—2350.
VIDEO
PROJECTOR
enhancement technique, thereby making the features of the
object easier to distinguish.
23 Claims, 9 Drawing Sheets
U.S. Patent
Oct.19,1999
Sheet 1 of9
5,969,754
U.S. Patent
Oct.19,1999
Sheet 2 of9
5,969,754
LJ‘_U
PROJECT
U.S. Patent
Oct.19,1999
Sheet 3 of9
5,969,754
m
N.
IE1
ln-'i]
E03 5 8
U.S. Patent
Oct.19,1999
Sheet 4 0f 9
5,969,754
U.S. Patent
Oct.19,1999
Sheet 5 of9
5,969,754
U.S. Patent
Oct.19,1999
Sheet 6 of9
5,969,754
U.S. Patent
Oct.19,1999
Sheet 8 of9
5,969,754
<m m
F103 mo j m
@ZEQOMW
w
02%W
OhmNOMS;EH53_\/ D9).9 7
OM53
<Dmo2<w
“ILEm015
U.S. Patent
Oct. 19, 1999
Sheet 9 0f 9
5,969,754
Fi_.5B
5,969,754
1
2
CONTRAST ENHANCING ILLUMINATOR
transmits a portion of the light that reaches it. The beam
separator is positioned betWeen the video imaging means
and the object, and betWeen the video projector and the
TECHNICAL FIELD
object, such that the visual image projected by the video
projector illuminates the object from the same perspective
that the video imaging means vieWs the object, thus causing
the features of the projected visual image to overlay the
corresponding features of the object.
In the preferred embodiment of the invention, the light
The present invention relates to a method and apparatus
for enhancing the visibility of an object to observers of the
object. More particularly, it relates to a method and appa
ratus for increasing the contrast betWeen bright and dark
areas of an object by projecting an image of the object onto
the object.
10
source is an infrared light source, such as an array of infrared
light emitting diodes, or a White light source housed in a
BACKGROUND
container that only alloWs infrared light to escape. The ?lter
As a result of the normal aging process, and as a result of
is of a type, and the beam separator is of a type Which re?ects
diseases such as AIDS, diabetes, and multiple sclerosis, a
patient experiences degeneration in the central portion of the
15
retina of the eye, the macula retinae. This condition causes
the patient dif?culty in distinguishing anything other than
visible light and transmits infrared light. This embodiment
prevents visible light from the video projector from reaching
the video imaging means While alloWing infrared light,
re?ected from the object, to reach the video imaging means.
The video imaging means of the preferred embodiment is
a charge coupled device (CCD) video camera, and the video
very high contrast objects, such as large black letters on a
White background. A normal scene of daily life, such as
various foods on a plate, becomes almost impossible to
projector is a liquid crystal display (LCD) video projector. In
interpret due to the patient’s inability to distinguish the light
an alternate embodiment a digital mirror display (DMD)
and dark areas of the scene.
may be used as the video projector.
In an alternative embodiment of the invention, the vis
The contrast of a scene could be enhanced for the patient
by means of a pair of glasses equipped With a video display
ibility of the object is further enhanced by increasing the
fed With a video signal from a video camera mounted on the 25 de?nition of the edges of the object using an unsharp
patient’s head. The contrast of the video display could be
adjusted to enhance the contrast of the scene vieWed by the
masking edge enhancement technique. The video imaging
means of this embodiment is comprised of a ?rst video
video camera. Unfortunately, such an apparatus Would
camera Which measures source light re?ected from the
require the patient to carry added Weight on his head and get
object in the form of a focused image and generates a video
used to a completely neW Way of vieWing the World.
Hence, it is desirable to enhance the contrast of a scene
While alloWing the patient to vieW the scene With his oWn
output signal representative of the focused image, and a
second video camera Which measures source light re?ected
eyes. Such contrast enhancement may be accomplished by
selective illumination of the scene. Areas of the scene With
high re?ectivity are illuminated more strongly, While areas
of loWer re?ectivity are illuminated less strongly. In this
manner, bright areas become brighter While dim areas
35
from the object in the form of a defocused image and
generates a video output signal representative of the defo
cused image. A difference ampli?er produces at its output a
video signal representing the difference betWeen the video
signals from the tWo video cameras.
In a second alternative embodiment of the invention, the
video signals from the tWo video cameras are converted into
remain dim, resulting in contrast enhancement. To achieve
color enhancement, each of the three primary colors may be
contrast enhanced independently.
It is also desirable to enhance the edges of features in the
prised of a ?rst logarithmic ampli?er Which converts the
scene to distinguish the transition from one feature of a
video signal at the output of the ?rst video camera into a ?rst
logarithmic video signals prior to subtracting them. The
video imaging means of this embodiment is further com
logarithmic video signal, a second logarithmic ampli?er
scene to the neXt.
SUMMARY
45
Which converts the video signal at the output of the second
video camera into a second logarithmic video signal, and a
difference ampli?er Which produces at its output a logarith
mic video signal representing the difference betWeen the ?rst
and second logarithmic video signals at its input. An inverse
logarithmic ampli?er produces at its output the inverse
logarithm of the logarithmic difference video signal at its
The present invention is directed to an illumination appa
ratus that satis?es the need for a means of enhancing the
contrast of an object While alloWing an observer to vieW the
object directly With his oWn eyes. The illumination appara
tus alters the visual contrast betWeen bright and dark areas
of an object by projecting a visual image of the object onto
the object. The apparatus consists of a light source Which
input.
image and creates a video output signal representative of the
image, and a video projector Which receives the video signal
from the video imaging means and projects a visual image
Which is representative of the image measured by the video
digital frame capture means Which converts the analog video
signals at the output of the ?rst and second video cameras
into a digital format Which may be processed by a digital
processor. A digital processor performs a digital subtraction
of the tWo digital video signals to form a digital difference
signal, and a digital-to-analog frame output means converts
the digital difference signal into an analog video output
In a third alternative embodiment of the invention, the
illuminates the object, a video imaging means Which mea
subtraction of the tWo video signals is performed in a digital
sures source light re?ected from the object in the form of an 55 format. This embodiment further comprises an analog-to
imaging means. The apparatus also includes a ?lter Which
prevents video projector light from reaching the video
imaging means While alloWing source light, re?ected from
the object, to reach the video imaging means. In this manner,
the ?lter eliminates positive feedback Which Would degrade
the desired visual effect.
An alternative embodiment of the invention further con
sists of a beam separator Which re?ects a portion and
signal.
65
The method of the present invention alters the visual
contrast betWeen bright and dark areas of an object by
projecting a visual image of the object onto the object, Where
the visual contrast is sensed by a direct observer of the
5,969,754
3
4
object. The method includes the steps of illuminating the
object by means of a light source, measuring the light
object 4 as vieWed by an observer 6. A light source 8
re?ected from the object in the form of an image and
the object in the direction of the observer 6 and in the
direction of the apparatus. Because of irregularities in the
surface of the object 4, and differences in the re?ective
illuminates the object resulting in the re?ection of light from
creating a video output signal representative of the image,
and projecting a visual image, Which is representative of the
video signal at the output of the light measuring means, onto
the object. The visual image is projected in such a manner
that the visual image illuminates the object from the same
perspective that the light measuring means vieWs the object.
In this manner, the features of the projected visual image
overlay the corresponding features of the object.
properties over different areas of the object 4, some areas of
the object 4 re?ect light more brightly than others. The
contrast in light intensity betWeen bright and dark areas can
10
The method of the invention also includes the step of
?ltering the light Which enters the light measuring means
such that light from the projecting means is not measured by
the light measuring means, While light from the illuminating
means, Which is re?ected from the object, is measured by the
light measuring means. This step eliminates positive feed
back Which Would degrade the desired visual effect.
be intensi?ed by projecting an image of the object 4 back
onto the object 4, such that the features of the projected
image overlay the corresponding features of the object 4. In
this manner, the bright areas become brighter While the dark
areas remain dark, thus enhancing contrast.
Conversely, the contrast in intensity betWeen the bright
15
steps of measuring the light re?ected from the object in the
and dark areas of the object 4, as sensed by the observer 6,
may be decreased by projecting an inverse image of the
object 4 back onto the object 4. The bright and dark areas are
inverted in the inverse image such that When the inverse
image is projected onto the object 4, the dark areas of the
object 4 are made brighter and the bright areas of the object
form of a focused image and creating a ?rst video output
4 remain the same.
In an alternative method of the invention incorporating
edge enhancement, the light measuring step includes the
signal representative of the focused image, measuring the
With continued reference to FIG. 1, light from the light
light re?ected from the object in the form of a defocused
image and creating a second video output signal represen
tative of the defocused image, and subtracting the ?rst video
source 8 re?ects from the object 4, and passes into the video
25
signal from the second video signal to form a difference
video output signal.
BRIEF DESCRIPTION OF THE DRAWINGS
The preferred embodiments of the invention Will noW be
the video projector 12. The video projector 12 projects an
image onto the object 4, the image corresponding to the
video signal at the input of the projector 12. The image
Which is projected by the video projector 12 onto the object
described in further detail. Other features, aspects, and
advantages of the present invention Will become better
understood With regard to the folloWing description,
4 is basically the same image as that received by the video
camera 10, or it is the inverse of the image as discussed
appended claims, and accompanying draWings Where:
FIG. 1 is a functional block diagram of an embodiment of
the invention;
camera 10. The video camera lens 30 forms the re?ected
light into a visual image Which the video camera 10 converts
into an electrical video signal. This electrical signal is fed
from the video output of the video camera 10 to the input of
35
FIG. 2a is a functional block diagram of an alternative
previously.
With continued reference to FIG. 1, a distance measuring
device 42 measures the distance betWeen the illumination
embodiment of the invention Which incorporates high-speed
apparatus and the object 4, and produces an electrical signal
shutters shoWn during a ?rst half-cycle of the shutter
Which is representative of the measured distance. This
sequence;
FIG. 2b is a functional block diagram of an alternative
electrical signal is fed to the video camera 10 Which makes
the necessary adjustments, based on the measured distance
embodiment of the invention Which incorporates high-speed
to the object, to bring the image of the object 4 into focus.
Similarly, the electrical signal from the distance measuring
shutters shoWn during a second half-cycle of the shutter
device is fed to the video projector 12 Which makes the
sequence;
FIG. 2c is a functional block diagram of a preferred 45 necessary adjustments, based on the measured distance to
the object, to bring the projected image of the object 4 into
embodiment of the invention incorporating a cold mirror
focus. The distance measuring device 42 determines the
distance betWeen the illumination apparatus and the object 4
by measuring the time required for a pulse, such as an
ultrasonic pulse, emitted from the distance measuring device
42 to travel to and re?ect from the object 4, and travel back
to the distance measuring device 42.
beam separator;
FIG. 2a' is a functional block diagram of a preferred
embodiment of the invention incorporating a hot mirror
beam separator;
FIG. 3 is a functional block diagram of an alternative
embodiment of the invention incorporating contrast
In an alternative embodiment of the invention as shoWn in
enhancement and analog edge enhancement;
FIG. 4 is a functional block diagram of an alternative
embodiment of the invention incorporating contrast
55
the video camera 10. As above, the video camera lens 30
enhancement and digital edge enhancement;
forms the re?ected light into a visual image Which the video
FIG. 5a is a functional block diagram of an alternative
camera 10 converts into an electrical video signal. This
embodiment of the invention incorporating analog edge
enhancement only; and
electrical signal is fed from the video output of the video
camera 10 to the input of the video projector 12. In this
FIG. 5b is a functional block diagram of an alternative
embodiment of the invention incorporating digital edge
enhancement only.
DETAILED DESCRIPTION OF PREFERRED
EMBODIMENTS
ShoWn in FIG. 1 is an illumination apparatus 2 Which
alters the contrast betWeen bright and dark features of an
FIG. 2a, light from the light source 8 re?ects from the object
4 and passes through the beam separator 16 prior to entering
65
embodiment, the video projector 12 projects an image onto
the beam separator 16, the image corresponding to the video
signal at the input of the projector 12. As shoWn in FIG. 2b,
the beam separator 16 re?ects the projected image back onto
the object 4.
The beam separator 16 is precisely positioned relative to
the video camera 10 and the video projector 12 so that the
5,969,754
5
6
image re?ected from the beam separator 16 and onto the
object 4 follows a path to the object 4 Which coincides With
visible light from the video projector 12 that passes through
the beam separator 16. The boX also prevents any infrared
light from reaching the video camera 10 directly from the
light source 8. As shoWn in FIG. 2c, the light-absorbing boX
18 has three apertures, one Which passes light from the video
projector 12 to the beam separator 16, one Which passes light
the path followed by the light re?ected from the object 4 to
the video camera 10. In other Words, the video camera vieWs
the object, and the object, from the same perspective. In this
manner, the bright and dark features of the projected image
precisely overlay the corresponding bright and dark features
from the beam separator 16 to the video camera 10, and one
of the object image as detected by the video camera 10.
The light from the video projector Which re?ects from the
Which passes light betWeen the object 4 and the beam
separator 16.
The beam separator 16 of the embodiment shoWn in FIG.
2a' is an Edmund Scienti?c Company Model 43,453 hot
mirror Which transmits visible light but re?ects infrared
light. In this embodiment, the infrared light re?ected from
the object is re?ected from the hot mirror beam separator 16
object 4 must be prevented from being detected by the video
10
camera 10. OtherWise, this re?ected light Would pass into
the video camera 10, transfer to the video projector 12 in the
form of a video signal, project back onto the object 4, and
be re?ected back to the video camera 10, thus forming a
positive feedback loop. If not prevented, such positive
15
feedback Would lead to the creation of an unstable or binary
and into the video camera 10.
The video camera 10 of the embodiments depicted in
image.
FIGS. 2c and 2a' is a Cohu Model 631520010000 mono
One method of making the video camera 10 insensitive to
chrome charge coupled device (CCD)) video camera. The
light from the video projector 12, and thus eliminating
positive feedback, is to place high-speed shutters in front of
video camera lens 30 is a Tokina AT-X AF 17 mm f3.5
20
the video camera 10 and the video projector 12. During a
?rst half-cycle of shutter operation as shoWn in FIG. 2a, the
?rst shutter 48a in front of the video camera 10 is open, and
the second shutter 48b in front of the video projector 12 is
closed, thus blocking the video projector light While the
25
Nikon-mount lens. The ?lter 14, mounted on the front of the
video camera lens, is an Edmund Scienti?c Company Model
32,766 infrared transmitting ?lter With a 695-mm cutoff
Wavelength Which only alloWs infrared light to enter the
video camera 10. To provide the necessary angular
adjustment, the video camera 10, lens 30, and ?lter 14 are
video camera 10 measures only the source light re?ected
mounted on an adjustment stage, such as a Bogen Model
from the object 4. During a second half-cycle, as shoWn in
3275, Which provides for elevation, aZimuth, and roll angu
lar positioning. The three-angle adjustment stage is mounted
FIG. 2b, a ?rst shutter 48a in front of the video camera 10
is closed, and a second shutter 48b in front of the video
on a tripod, such as a Bogen Model 3020.
The video camera lens 30 of this embodiment corrects a
projector 12 is open, thus alloWing the video projector light
to illuminate the object 4, but precluding video projector
light from reaching the video camera 10.
Alternatively, a preferred embodiment of the invention
prevents positive feedback by employing a ?lter 14 in front
of the video camera lens 30 as shoWn in FIGS. 2c and 2d.
distortion of the projected image introduced by the Epson
Model ELP-3000 video projector 12. This model projector is
designed to project an image on an overhead screen Whose
35
This ?lter 14 rejects light from the video projector 12 While
passing light from the light source 8 Which is re?ected from
the object 4. For the ?lter 14 to perform this function, the
source light re?ected from the object 4 must in some Way
differ from the light projected by the video projector 12.
to correct for the “keystone” distortion effect Which occurs
With oblique angles of projection. In keystone distortion, the
magni?cation of the image varies With vertical position on
40
FIGS. 2c and 2d, the light source 8 is an infrared light
45
keystone distortion is corrected by vertically offsetting the
(Edmund Scienti?c Company Model 52,580) Which consists
eXample is a White light, such as a GE 45-Watt ?ood lamp,
contained Within a housing that is light-tight eXcept for an
aperture covered by an infrared-transmitting ?lter, such as
an Edmund Scienti?c Company Model 60,033. The video
projector 12 of this embodiment is an Epson Model ELP
50
55
and into the video camera 10. The beam separator 16 is
mounted in a light-absorbing boX 18 Which absorbs any
mount With a means for vertical position adjustment, such as
the Nikon PB-6 BelloWs lens mount system With an addi
enhances the edges of an object 4 using an unsharp masking
technique. With this technique, a blurred version of the
object image is produced and is subtracted from the original
object image to produce an edge-enhanced image.
The light source 8, video projector 12, ?lter 14, and
light in the visible range. In an alternate embodiment a
display Which incorporates a digital micromirror device
(DMD), such as that produced by Texas Instruments, Inc.,
mirror Which transmits infrared light but re?ects visible
light. In this embodiment, the infrared light re?ected from
the object passes through the cold mirror beam separator 16
video camera lens 30 With respect to the optical aXis of the
camera. This vertical offset is accomplished using a lens
tional vertical ?ne motion control stage.
A ?rst alternative embodiment of the invention visually
3000 liquid crystal display (LCD) projector Which emits
may be used as the video projector.
The beam separator 16 of the embodiment shoWn in FIG.
2c is an Edmund Scienti?c Company Model 42,414 cold
height, such that the projection aXis of the video projector 12
forms an angle of nearly 90 degrees With the surface of the
object 4. In this situation, the offset lens of the video
projector 12 Would cause the image projected onto the object
4 to have an “inverted keystone” distortion. The inverted
eXample of such a light source is an Electrophysics Corpo
ration Model IRL600 Infrared Microbeam Safelight
of an array of infrared light emitting diodes (LEDs). Another
a screen, With a larger magni?cation at the top of the screen
than at the bottom. HoWever, in typical operation of the
invention, the projector 12 and the object 4 are at the same
The preferred method of achieving this difference is to
separate the tWo light signals in Wavelength. As shoWn in
source, emitting light With a Wavelength longer than 695
nanometers Which is longer than visible Wavelengths. One
surface is at an oblique angle to the projection aXis. This
model projector incorporates a lens Which is offset vertically
60
light-tight boX 18 of this alternative embodiment are iden
tical to, or functionally equivalent With, the corresponding
components of the previously described embodiment.
HoWever, as shoWn in FIG. 3, this embodiment incorporates
65
tWo video cameras 10a and 10b, such as Cohu Model
631520010000 monochrome CCD video cameras, each
vieWing the object 4 from the same perspective by means of
a beam splitter 28, such as an OptoSigma 055-0165 infrared
5,969,754
7
8
beam splitter prism. The beam splitter 28 provides one half
of the light re?ected from the object 4 to each of the video
angle prism or mirror, provides a reversal of the object
video output device 36, may be fed to the input of a video
display device 50, such as a television monitor, or to the
input of a video recording device 52, such as a video cassette
recorder. With this embodiment, the observer 6 vieWs the
image detected by the ?rst camera 10a to match the re?ected
edge-enhanced image of the scene by vieWing either the live
(and, therefore, reversed) object image detected by the
or recorded image by means of the video display device 50.
Prior to using the invention shoWn in FIG. 3 for contrast
cameras 10a and 10b. Are?ecting surface 44, such as a right
second camera 10b. One of the cameras is sharply focused
While the other is defocused to provide a blurred version of
the object image. A Zoom lens 46, such as a Vivitar 17—28
mm f 4.0—4.5 lens, alloWs adjustment of the siZe of the
object image detected by the ?rst camera 10a so that the
focused and defocused object images are the same siZe.
The frame capture of the tWo cameras is synchroniZed by
or edge enhancement, the image of the object 4 captured by
the video camera 10 (or video cameras 10a and 10b) and
10
object 4. This is accomplished by adjusting the three angular
adjustments on the geared tripod head, the vertical offset
adjustment of the video camera lens 30, and the Zoom
control of the video projector lens.
means of a locking circuit, such as the GENLOCK circuit
Which is integral to the Cohu Model 631520010000 video
camera. To enable the frame synchroniZation, the GEN
projected by the video projector 12 must be aligned With the
15
In operation, the invention is used in a darkened room
such that the only visible light illuminating the object 4 is
LOCK ports of the tWo video cameras 10a and 10b are
connected by means of a video cable 40.
The video camera lenses 30a and 30b of this embodiment
are also mounted using lens mounts With means for vertical
from the video projector 12. The observer 6 vieWs the object
4 from nearly the same perspective as that of the video
camera 10 so that the region of the object 4 being illumi
nated by the video projector 12 is Within the observer’s ?eld
of vieW. The observer 6 adjusts the brightness and contrast
controls of the video projector 12 to achieve the optimum
enhancement of the object 4.
position adjustment to correct for the keystone distortion
introduced by the Epson video projector.
The electrical signals at the outputs of the focused and
defocused video cameras 10a and 10b are ampli?ed and
As mentioned previously, such a device could be used to
offset by means of variable gain and offset ampli?ers 20 and
22. The signals at the output of the ampli?ers 20 and 22 are
subtracted by means of a difference ampli?er 24, and the
difference signal is fed to the input of another variable gain
and offset ampli?er 26. Since the horiZontal and vertical
synchroniZation signals are lost in the subtraction of the
enhance the contrast of objects vieWed by patients suffering
from degeneration of the macula retinae. The apparatus
could also ?nd application in surgery Where it Would be used
as an illumination device to make it easier for a surgeon to
30
the horiZontal and vertical synchroniZation signals from one
of the video cameras. The composite video signal at the
output of the summing circuit 38 is fed to the input of the
performances, and discotheques.
It is contemplated, and Will be apparent to those skilled in
35
the art from the foregoing speci?cation, draWings, and
eXamples that modi?cations and/or changes may be made in
the embodiments of the invention. Accordingly, it is
expressly intended that the foregoing is illustrative of pre
ferred embodiments only, not limiting thereto, and that the
true spirit and scope of the present invention be determined
by reference to the appended claims.
What is claimed is:
1. An illumination apparatus Which alters the visual
video projector 12. As With the previously described
embodiment, the video projector 12 projects the visible-light
object image onto the beam separator 16 Which re?ects the
object image onto the object 4. In this manner, the edge
enhanced image features overlay the object features.
contrast betWeen bright and dark areas of an object as sensed
In a second alternative embodiment of the invention, a
logarithmic subtraction of the video signals from the tWo
are also contemplated in the entertainment area, such as the
creation of interesting lighting effects at concerts, theatrical
video camera signals, these signals must be added back to
the difference signal to form a composite video signal. This
is accomplished by summing circuit 38 Where the difference
video signal at the output of the ampli?er 26 is summed With
distinguish similar types of tissue. Numerous applications
45
by a direct observer of the object, the apparatus comprising:
video cameras is performed. With continued reference to
FIG. 3, the ampli?ers 20 and 22 of this embodiment are
a light source Which illuminates the object With source
logarithmic ampli?ers, and the ampli?er 26 is an inverse
a video imaging means Which measures source light
light having a ?rst property;
logarithmic ampli?er.
re?ected from the object, the re?ected light measured
Athird alternative embodiment of the invention performs
in the form of an image, said video imaging means
the subtraction of the tWo video camera signals in a digital
creating a video output signal representative of the
image;
format. As shoWn in FIG. 4, the analog video signals at the
outputs of the video cameras 10a and 10b are converted into
digital format by an analog-to-digital frame capture device
32, such as a Miro DC-20 Video Capture board. Acomputer
55
object, forming a visual image Which is representative
of the visual image received by said video imaging
means, such that the visual image projected by said
34 incorporating a high-speed processor, such as a Pentium
processor operating at 133 MHZ, and suf?cient memory,
such as 32 megabytes of RAM, calculates the difference of
the focused and defocused video signals at about 2—5 frames
per second. It is contemplated that higher frame rates may be
attained by means of a faster processor. The digital differ
ence signal is fed to a digital-to-analog (D/A) video output
device 36, such as a Miro 20-TD Live Video Display board,
Which converts the digital difference signal into an analog
60
video signal that is compatible With the video projector 12.
65
With reference to FIGS. 5a and 5b, the video signal at the
output of the summing circuit 38, or at the output of the D/A
a video projector Which receives the video output signal
from said video imaging means and projects video
projector light having a second property onto the
video projector illuminates the object from the same
perspective that said video imaging means vieWs the
object, Whereby the features of the projected visual
image overlay the corresponding features of the object;
and
a ?lter Which distinguishes betWeen the ?rst and second
properties and prevents the video projector light from
reaching said video imaging means While alloWing the
source light, re?ected from the object, to reach said
5,969,754
10
video imaging means, thus eliminating positive feed
of a focused image, said camera creating a ?rst video
output signal representative of the focused image;
back Which Would degrade the desired visual effect.
2. The illumination apparatus of claim 1 further compris
ing a beam separator Which re?ects a portion and transmits
a portion of the light that reaches it, said beam separator
being positioned betWeen said video imaging means and the
object, and betWeen said video projector and the object.
3. The illumination apparatus of claim 2 Wherein said
?lter is of a type Which transmits infrared light but not
visible light, and said beam separator is of a type Which
a second video camera Which measures source light
re?ected from the object, the re?ected light measured
in the form of a defocused image, said camera creating
a second video output signal representative of the
defocused image;
an analog-to-digital frame capture means Which converts
the analog video signals at the output of said ?rst and
10
re?ects visible light and transmits infrared light.
be processed by a digital processor;
the digital processor Which performs a digital subtraction
of the tWo digital video signals to form a digital
difference signal; and
4. The illumination apparatus of claim 2 Wherein said
?lter is of a type Which transmits infrared light but not
visible light, and said beam separator is of a type Which
transmits visible light and re?ects infrared light.
15
5. The illumination apparatus of claim 1 Wherein said
signal.
projector.
11. The illumination apparatus of claim 1 further com
prising a distance measuring device Which measures the
6. The illumination apparatus of claim 1 Wherein said
video projector is a digital mirror display (DMD) video
projector.
7. The illumination apparatus of claim 1 Wherein said
video imaging means is a charge coupled device (CCD)
video camera.
25
a ?rst video camera Which measures source light re?ected
from the object, the re?ected light measured in the form
of a focused image, said camera creating a ?rst video
output signal representative of the focused image;
distance betWeen the illumination apparatus and the object
and produces an electrical signal representative of this
distance, said video imaging means and said video projector
being operable to receive the electrical signal from said
distance measuring device and focus the object image cor
responding to the distance represented by the electrical
signal from said distance measuring device.
12. The illumination apparatus of claim 1 Wherein the
light emanating from said light source is infrared light.
13. The illumination apparatus of claim 12 Wherein said
light source is comprised of a White light source housed in
a container that only alloWs infrared light to escape.
14. The illumination apparatus of claim 12 Wherein said
a second video camera Which measures source light
re?ected from the object, the re?ected light measured
in the form of a defocused image, said camera creating
a second video output signal representative of the
defocused image; and
a digital-to-analog frame output means Which converts the
digital difference signal into an analog video output
video projector is a liquid crystal display (LCD) video
8. The illumination apparatus of claim 1 Wherein said
video imaging means includes:
second video cameras into a digital format Which may
light source is comprised of an array of infrared light
35
a difference ampli?er Which produces at its output a video
emitting diodes.
15. The illumination apparatus of claim 1 Wherein said
?lter comprises:
signal representing the difference betWeen the ?rst and
second video output signals present at its input.
a ?rst shutter means Which opens and closes cyclically,
said ?rst shutter means being open during a ?rst
9. The illumination apparatus of claim 1 Wherein said
video imaging means includes:
?rst shutter means alloWing source light re?ected from
a ?rst video camera Which measures source light re?ected
the object to reach the video imaging means only
half-cycle and closed during a second half-cycle, said
from the object, the re?ected light measured in the form
during the ?rst half-cycle;
of a focused image, said camera creating a video output
signal representative of the focused image;
a second video camera Which measures source light
45
re?ected from the object, the re?ected light measured
in the form of a defocused image, said camera creating
a video output signal representative of the defocused
image;
logarithmic video signal;
second logarithmic video signal;
half-cycle and open during a second half-cycle, said
second shutter means alloWing light projected from the
video projector to reach the object only during the
second half-cycle; and
a synchroniZing means Which causes the ?rst shutter
means to open only after the second shutter means is
a ?rst logarithmic ampli?er Which converts the video
signal at the output of said ?rst video camera into a ?rst
a second logarithmic ampli?er Which converts the video
signal at the output of said second video camera into a
a second shutter means Which opens and closes cyclically,
said second shutter means being closed during a ?rst
55
completely closed, and causes the second shutter means
to open only after the ?rst shutter means is completely
closed.
16. The illumination apparatus of claim 15 Wherein said
?rst and second shutter means operate at no less than 120
cycles per second.
a difference ampli?er Which produces at its output a
logarithmic video signal representing the difference
17. A method of altering the visual contrast betWeen
betWeen the ?rst and second logarithmic video signals
at its input; and
an inverse logarithmic ampli?er Which produces at its
output a video signal Which is the inverse logarithm of
the logarithmic difference video signal at its input.
bright and dark areas of an object as sensed by a direct
10. The illumination apparatus of claim 1 Wherein said
video imaging means includes:
a ?rst video camera Which measures source light re?ected
from the object, the re?ected light measured in the form
observer of the object, the method comprising the steps of:
illuminating the object by means of a light source having
a ?rst property;
measuring the light re?ected from the object in the form
65
of an image and creating a video output signal repre
sentative of the image;
projecting a visual image With light having a second
property, Which is representative of the video output
5,969,754
11
12
signal at the output of the light measuring means, onto
measuring the light re?ected from the object in the form
the object in such a manner that the projected visual
of a defocused image and creating a second linear video
output, signal representative of the defocused image;
image illuminates the object from the same perspective
that the light measuring means vieWs the object, thus
causing the features of the projected visual image to
overlay the corresponding features of the object; and
?ltering the light Which enters the light measuring means
such that light having the second property from the
converting the ?rst linear video signal, Which represents
the focused image, into a ?rst logarithmic video signal;
converting the second linear video signal, Which repre
sents the defocused image, into a second logarithmic
video signal;
subtracting the ?rst logarithmic video signal from the
projecting means is not measured by the light measur
ing means, While light having the ?rst property from the
illuminating means, Which is re?ected from the object,
is measured by the light measuring means, thus elimi
nating positive feedback Which Would degrade the
10
logarithmic video signal; and
converting the difference logarithmic video signal into a
linear video output signal representative of the object
image.
desired visual effect.
23. A method of altering the visual contrast betWeen
18. The method of claim 17 Wherein the light measuring
bright and dark areas of an object as sensed by a direct
means is a CCD video camera.
observer of the object, the method comprising the steps of:
illuminating the object by means of an infrared light
19. The method of claim 17 Wherein the projecting means
is an LCD video projector.
20. The method of claim 17 Wherein the projecting means
is a DMD video projector.
source;
measuring the infrared light re?ected from the object in
the form of an image and creating a video output signal
21. The method of claim 17 Wherein said light measuring
step further comprises the steps of:
measuring the light re?ected from the object in the form
representative of the image;
of a focused image and creating a ?rst linear video
output signal representative of the focused image;
25
measuring the light re?ected from the object in the form
of a defocused image and creating a second linear video
output signal representative of the defocused image;
and
subtracting the ?rst linear video signal from the second
linear video signal to form a difference linear video
output signal.
22. The method of claim 17 Wherein said light measuring
step further comprises the steps of:
measuring the light re?ected from the object in the form
second logarithmic video signal to form a difference
projecting a visual image With visible light, Which is
representative of the video output signal at the output of
the light measuring means, onto the object in such a
manner that the projected visual image illuminates the
object from the same perspective that the light mea
suring means vieWs the object, thus causing the fea
tures of the projected visual image to overlay the
corresponding features of the object; and
?ltering the light Which enters the light measuring means
such that the visible light from the projecting means is
not measured by the light measuring means, While
infrared light from the light source, Which is re?ected
from the object, is measured by the light measuring
35
means, thus eliminating positive feedback Which Would
degrade the desired visual effect.
of a focused image and creating a ?rst linear video
output signal representative of the focused image;
*
*
*
*
*
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertisement