Facsimile and static presentation processing – Natural color facsimile – Scanning
Reexamination Certificate
1999-01-26
2003-07-08
Grant, II, Jerome (Department: 2624)
Facsimile and static presentation processing
Natural color facsimile
Scanning
C382S318000
Reexamination Certificate
active
06590679
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates to the scanning of photographic images, and more particularly in a primary application, to scanning in infrared and visible light in order to prepare for correction of surface defects.
BACKGROUND OF THE INVENTION
FIG. 1
shows a prior art trilinear film scanner, and also introduces some terms that will be used in this application. A lamp
102
transilluminates a filmstrip
104
containing an image
106
to be scanned. Normally the light from the lamp
102
would be diffused or directed by additional optics, not shown, positioned between the lamp
102
and film
104
in order to illuminate the image
106
more uniformly. The image
106
on the film
104
is focused by lens
108
onto a sensor line
110
in a circuit package
112
. The sensor line
110
projects back through lens
108
as a line
116
across the image
106
. This line
116
is composed of many individual points, or pixels. To scan the entire image
106
, the film
104
is moved perpendicularly to the line
116
to scan a two dimensional area, such as image
106
. Because the sensors of the sensor line
110
are positioned in lines, this arrangement is called a linear, or line, sensor.
The sensor line
110
may be of a form known in the art as a “trilinear”, or three line, array. As shown magnified at
120
, the sensor line
110
actually consists of three parallel lines of sensors. In this prior art embodiment, one line of sensors
122
is behind a line of red filters
124
. This arrangement could consist of a series of independent filters, but is normally a single long red filter
124
which covers all of the sensors of line
122
. Another line of sensors
126
is behind a green filter line
128
, and a third line of sensors
130
is behind a blue filter line
132
.
As the film
104
is moved, the three lines
122
,
126
, and
130
each provide an individual image of the film seen with a different color of light. The data from the circuit package
112
is sent along cable
136
to supporting electronics and computer storage and processing means, shown together as computer
138
. Inside computer
138
the data for each color image is grouped together, and the three images are registered as the three color planes
140
,
142
, and
144
of a full color image. Each of these color planes
140
,
142
and
144
consists of pixels describing with a number the intensity of the light at each point in the film. For example, pixel
150
of the red color plane
144
may contain the number “
226
” to indicate a near white light intensity at point
152
on the film
104
, as measured at a specific sensor
154
in the array
110
, shown enlarged in circle
120
as sensor
156
behind the red filter line.
In
FIG. 1
it is noted that there is a spacing between sensor lines
122
,
126
and
130
, and therefore the same point on the film
104
is not sensed by all three color lines at the same point in time.
FIG. 2
illustrates this registration problem in more detail.
In
FIG. 2
there is a trilinear array (not shown) with red, green, and blue sensor lines
202
,
204
, and
206
. These lines are projected onto a substrate (not shown) which is moved in the direction of the arrow to scan out regions of the image on the substrate. The region seen by each line is different from the region seen by the other lines. For example, at the beginning of an arbitrary time interval, sensor
210
of the blue line
206
may see point
212
of the substrate, while at the end of the time interval, it may see point
214
. It is apparent that each of the different sensors
210
,
220
and
230
sees a different area during the same time interval. For example, at the end of the time interval, sensor
220
of the red sensor array
202
sees point
222
, which is different than point
214
seen by the blue sensor
210
at the same end time. However, if the time interval is long enough, there will exist a region of overlap
224
over which all array lines have passed. If the interval between measurements is an integer submultiple of the spacing between the arrays, then there exists a time at which sensor
230
of the green line
204
sees the same point
232
on the substrate as
214
, and another time at which sensor
220
of the red line
202
sees point
234
, the same as point
214
, which in turn will be seen by the blue sensor
210
at a later time. The computer system
138
receiving the information from the scans made by the trilinear array registers the data representing the three color images by shifting the data an amount corresponding to the distance between sensor lines, and discarding the part of each color record outside the full color range overlap
224
.
Although this illustration has presented a so-called transmission, or film, scanner, a reflection, or print, scanner uses the same principles except that the source light is reflected from the same side as the imaging lens. As is explained later, there are uses for the present invention in both transmission and reflection scanners.
The conventional scanners described above scan in the three visible colors, exclusive of the invisible infrared. There are several reasons that it would be useful to add an infrared record registered to the conventional colored records. For example, examination of old documents under infrared with a reflection scanner is proving useful in examination of historic works, such as the Dead Sea Scrolls, to disclose alterations. Another potential use presented here without admission that it is known in the art, is to distinguish the “K” or black channel from the cyan, magenta, and yellow channels in a four color print. Currently a major commercial use of infrared plus visible scans is a technology called infrared surface defect correction, as explained in FIG.
3
. Current applications of infrared surface defect correction are limited to transmission scanners, although it may be extended to reflection scanners, and therefore the specific illustration of a transmission scanner given below is not to be considered a limitation.
In
FIG. 3
, a lamp
302
transilluminates filmstrip
304
containing an image
306
. An electronic camera
308
views the image
306
and outputs red, green, and blue digitized records
310
,
312
, and
314
. In addition the electronic camera
308
outputs an infrared record
316
. There are several ways a conventional camera can be made responsive to selectively visible and infrared light. One way is to provide a filter wheel
320
with four filters: red
322
, green
324
, blue
326
, and infrared
328
. If the camera
308
is a monochrome camera whose sensitivity extends into infrared, then the three visible colors and infrared may be captured at four different times, each time illuminating the film with a different filter in the filter wheel
320
.
The cyan, magenta, and yellow dyes that create the image
306
are all transparent to infrared light, and therefore the film
304
appears clear to camera
308
when viewed under infrared light. On the other hand, surface defects such as dust, scratches, and fingerprints refract the light passing through the film
304
away from the camera
308
, and therefore appear as darkened points under both visible and infrared light. Because refraction under infrared light is nearly equal to refraction under visible light, the defects appear nearly as dark in the infrared as in the visible spectrum.
Therefore infrared record
316
is effectively of a clear piece of film including defects, and image
310
contains the same defects plus the red image. The infrared image
316
provides a pixel by pixel “norming” for the effect of defects. For example, defect-free pixel
340
in the red record
310
may contain a 50% brightness measurement. The corresponding defect-free pixel
342
in the infrared record
316
contains 100% brightness because no defect has attenuated the light. Function block
344
divides the 50% brightness level from the red record
310
by the norming 100% brightness level from the infrared record
316
to give a 50% brightne
Edgar Albert D.
Penn Steven C.
Applied Science Fiction Inc.
Dinsmore & Shohl LLP
Grant II Jerome
Worku Negussie
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