Facsimile and static presentation processing – Natural color facsimile – Color photography previewer
Reexamination Certificate
1998-08-14
2001-04-03
Grant, II, Jerome (Department: 2722)
Facsimile and static presentation processing
Natural color facsimile
Color photography previewer
C358S506000, C358S505000, C358S487000
Reexamination Certificate
active
06211975
ABSTRACT:
FIELD OF THE INVENTION
The invention relates generally to the field of photographic film scanners and, more particularly, to method and apparatus for controlling image data collection and data transfer to a host computer.
BACKGROUND OF THE INVENTION
Photographic film scanners are known in which image frames on a strip of photographic film are scanned to convert the optical image frames into digital image data which can be stored and manipulated in a computer and, at the user's option, sent to a digital printer for generating hardcopy image prints. It is common in such scanners, to scan the image frame by transporting the film strip through an optical imaging path in which an exposure light source is shone through the image and focussed onto a linear CCD sensor to capture the image information one scan line at a time. The exposure light source may comprise a linear, interleaved array of spectrally distinct light emitting diodes (LED), for example, emitting in the red, blue and green spectra. In order to achieve accurate color rendition in the scanner it is necessary to perform a calibration of the LED exposure lights primarily to equalize the light outputs of the respective red, blue and green LED's. The analog pixel-by-pixel image information captured on the linear CCD light sensor must be clocked out of the CCD, digitized, processed and transferred to a host computer in synchronism with the transport motion of the film in such a manner that the transferred data is accurate and that no data is lost as a result of asynchronous operation between the scanner and the host computer. Internal operations of the scanner typically involve the use of separate timers to control the light source, film transport motor drive and data clocking/transfer functions, which require complex synchronizing provisions for control of the separate timers. Changing the scanning resolution complicates the control procedure as does changing the operating conditions of the R,B,G exposure light sources to accommodate for system drift and differing density characteristics among different film strips.
In the above cross-referenced copending U.S. application Ser. No. (Dkt 77989), a photographic film scanner is described that employs a programmed controller which operates in a manner to address the concerns just described. The controller is provided with a common timer and is programmed with a plurality of lookup tables (LUT), each LUT being populated with a sequence of elements defining timing of an operating activity of a respective one of the illuminant head light sources, the stepper motor and the light sensor data transfer circuits. The program operates to use the common timer to step synchronously through the elements of the LUT's to output value states from the elements of each of the LUT's; so as to suitably control the actuation timing of the respective light sources, stepper motor and data collection and transfer circuits. The arrangement described is a simple and convenient method and apparatus for control timing of critical operating functions in an image scanner. The use of a plurality of lookup tables provides flexible, independent control of the integration periods of the three different color planes.
The host computer operates in an asynchronous manner relative to the timing operation of the film scanner. The host computer can have other tasks to perform that need to be completed before it can accept data from the scanner. In the scanner operation described above, however, the scanner is integrating light from the LEDs and if the host is late in accepting data from the scanner, and incorrect amount of light will have been collected and a bright line will ultimately appear in the reproduced image. There is therefore a need in the scanner of the type described to accommodate asynchronous operation of the host computer so that delays in accepting data from the scanner do not adversely affect the image data being transferred and thus do not create artifacts in the image reproduced from the transferred data.
SUMMARY OF THE INVENTION
In accordance with one aspect of the invention, therefore, there is provided a method of controlling image data collection and image data transfer from a photographic film scanner to a host computer, the film scanner having a line integrating image sensor and operating under the control of a microprocessor controller, wherein the method comprises providing a plurality of lookup tables (LUT) in the controller, each LUT populated with a sequence of elements defining timing of an operating activity in a respective one of (a) transfer out from the scanner of a line of collected image data, (b) on/off operation of one or more scanning exposure light sources and (c) step operation of a film transport drive stepper motor; using a common timer to step synchronously through the elements of the LUT's to output value states from the elements of each of the LUT's; and responding to the synchronously outputted value states from the LUT's to effect timing of actuation of the data transfer, LED and film transport drive stepper motor operations in accordance with the value states of the LUT elements. The invention includes determining if transfer of data to the host computer is delayed for a time in excess of a line integration period of the image sensor; and responding to the determination of the excess data transfer time to disable the LEDs until such time as the transfer of data to the host is complete.
In another aspect of the invention, there is provided apparatus for controlling image data collection and image data transfer from a photographic film scanner to a host computer, wherein the apparatus comprises a film scan gate; a film transport drive stepper motor for advancing film through the scan gate during an image frame scan operation; an illuminant head having an array of spectrally separated light sources; a line integrating image light sensor; and light sensor data transfer circuits for collecting and transferring light sensor data to a host computer. The apparatus also includes a controller having a common timer and programmed with a plurality of lookup tables (LUT), each LUT populated with a sequence of elements defining timing of an operating activity in a respective one of the illuminant head light sources, the stepper motor and the light sensor data transfer circuits, the program operating to use the common timer to step synchronously through the elements of the LUT's to output value states from the elements of each of the LUT's, which value states effect timing of actuation of the data transfer, light sources and stepper motor operations; and wherein the program is further operative to determine if transfer of data to the host computer is delayed for a time in excess of a line integration period of the image light sensor; and responding to the determination of the excess data transfer time to disable the LEDs until such time as the transfer of data to the host is complete.
In a further aspect of the invention, an improvement in the method and apparatus as just described is provided in which a long delay time limit is established that corresponds to a time in which stored image information in said image sensor becomes unrepresentative of pixel values in a scanned image line even though the LED lights have been disabled to suspend image light integration in the image sensor. The controller then determines if the excess data transfer time exceeds the long delay time limit; and responds to the determination of exceeding the long delay time limit to flush the unrepresentative stored image information from the image sensor before recommencing data collection and data transfer after the completion of transfer of the prior line of collected data.
These and other aspects, objects, features and advantages of the present invention will be more clearly understood and appreciated from a review of the following detailed description of the preferred embodiments and appended claims, and by reference to the accompanying drawings.
REFERENCE
Boos, Jr. Francis H.
Eastman Kodak Company
Grant II Jerome
Kianni Kevin C
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