WO2023224482A1 - Method for improved scanning of a photographic emulsion - Google Patents

Method for improved scanning of a photographic emulsion Download PDF

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WO2023224482A1
WO2023224482A1 PCT/NL2023/050279 NL2023050279W WO2023224482A1 WO 2023224482 A1 WO2023224482 A1 WO 2023224482A1 NL 2023050279 W NL2023050279 W NL 2023050279W WO 2023224482 A1 WO2023224482 A1 WO 2023224482A1
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image
light
emulsion
angular
spatial
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PCT/NL2023/050279
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French (fr)
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R.J. Geluk
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Felixsonip B.V.
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/00795—Reading arrangements
    • H04N1/00798—Circuits or arrangements for the control thereof, e.g. using a programmed control device or according to a measured quantity
    • H04N1/00801—Circuits or arrangements for the control thereof, e.g. using a programmed control device or according to a measured quantity according to characteristics of the original
    • H04N1/00806—According to type of the original, e.g. colour paper or transparency, or reading a plurality of different types of original

Definitions

  • Photographic emulsions contain randomly distributed particles with light absorbing properties. When transilluminated, this chaotic distribution of particles causes unwanted modulation, known as film grain noise.
  • film grain noise is regarded as uncorrectable due to the lack of a fixed pattern for normalization.
  • the particles that carry the image information are chaotically distributed and, therefore, cause film grain noise, they are fixed in a three dimensional constellation. Consequently, the way in which they transmit and scatter light is deterministic by nature and no fundamental law of physics forbids correction of film grain noise as caused by this chaotic distribution of particles .
  • the present invention aims to retrieve e . g . historic images stored in photographic emulsions with a considerable higher quality than is possible with prior art methods , resulting in fundamentally improved representations of those images .
  • the present invention provides a method for scanning a photographic emulsion and retrieving an image stored therein and converting the retrieved image into a digital representation, the method comprising the steps of :
  • Fig.l shows light ray "L” that enters emulsion "E” and is partly transmitted and scattered.
  • Fig. 2 shows angular cones of transillumination.
  • Fig. 3 shows a callier surface of contrast "C" .
  • Fig. 4 shows a surface of spatial bandwidth "B" versus F- n umber .
  • Fig. 5 shows Callier ridge "CR" and two more cross sections .
  • Fig. 6 shows "CR” and "DL” indicating diffraction limitation .
  • Fig. 7 shows a light path of a system for limiting angular ranges .
  • Fig. 8 shows a light path for a system without moving parts .
  • Fig. 9 shows a system for spatial modulation.
  • Fig.10 shows signals related to the system of fig.9
  • Fig.11 shows a system having rotating polarization filters.
  • Fig.12 shows a system having circular polarization filters.
  • Emulsion "E” in fig 1 contains a stack of randomly distributed particles of different sizes, shapes and positions.
  • Light ray “L” transverses this stack of particles partly in a straight line at an angle a, producing transmitted ray "T” and also partly deflected producing scattered light ray "S".
  • Both rays "T” and “S” are subject to attenuation by the particles that carry image information.
  • Scattered light ray “S” may also be subject to multiple deflections, causing it to leave the emulsion with a lateral offset, causing unsharpness.
  • the transmission and scatter values vary to some degree due to the chaotic structure. Likewise, transmission and scatter values also vary with the lateral position. As all pixels are, independently, subject to this process, spatial image noise results.
  • Fig. 2 shows emulsion "E” being illuminated by a cone of light with angular range Aas which, after leaving the emulsion, is accepted over an angular range Aap.
  • Angular range Aas can be as large as 180 degrees for diffuse illumination, while angular range Aap depends on the imaging system that follows.
  • the accepted light flux within angular range Aap contains scattered light to a degree expressed by the scatter ratio.
  • the scatter ratio depends on the type of emulsion, film density and both angles Aas and Aap.
  • Aa is a general expression for linear angular range .
  • Callier was the first to investigate the effect of diffuse versus specular illumination on image contrast. This "Callier effect” has been quantified and related to film grain noise by Chavel and Lowenthal . This resulted in a surface of Contrast “C” as a function of both angular ranges Aas and Aap.
  • the "callier surface”, as shown in Fig.3, has a line of relative high contrast, here, indicated as Callier ridge "CR" .
  • Aas and Aap are equal. This condition is, also known as having a coherence ratio of 1 or "matched illumination” .
  • the downhill shape of the callier surface is due to scattering of light by particles and depends on film type, film density, grain size, grain shape grain distribution etc.
  • the callier surface can be transformed into a meaningful representation of image quality by plotting spatial bandwidth "B” rather than contrast "C” .
  • bandwidth "B” and contrast “C” follows from the Modulation Transform Function (MTF) , in that contrast “C” equals MTF at zero spatial frequency and bandwidth "B” equals the frequency at which the MTF has rolled off to a certain degree. Furthermore, we will plot the angular ranges in F-numbers as standardized in photography etc.
  • MTF Modulation Transform Function
  • this logarithmic scale renders the horizontal coordinates into a value proportional to log (1/N) .
  • the area product "I” of its vertical and horizontal coordinates reads as:
  • Equation (2) represents a relative amount of information density in the sense of Shannon's information theory.
  • objective value "I” is meant to be equivalent with “image quality”.
  • Fig.4 shows such a modified callier surface and two practical operating conditions of transillumination.
  • the first operating point: "D/5, 6" indicates diffuse illumination and an F/5, 6 imaging lens.
  • the second operating point “S/5, 6” indicates specular illumination, also with an F/5, 6 imaging lens.
  • the line that connects these different illumination conditions represents the variation of diffuse versus specular illumination according to Mead (EP0982939A2 ) .
  • Fig. 5 shows the callier ridge "CR" of fig.4 as well as the cross sections through the vertical axis and operating points "D/5, 6" and “S/5, 6" respectively. Dotted lines delineate enclosed areas of information density "I”.
  • Fig. 6 shows Callier ridge "CR” together with curve “DL” which represents spatial bandwidth limitation by diffraction.
  • the spatial bandwidth of the system is, therefore , limited by both curves of which condition "Ml” represents the condition for maximum information density .
  • Condition "Ml” corresponds to the particular condition of transillumination whereby the maximum density of information can be obtained according to the state of the art .
  • Such " structured light illumination” mixes down high spatial frequency components , into the spatial pass band of an imaging lens .
  • Subsequent image processing trans forms the resulting image signal into an extension of the spatial frequency spectrum .
  • the illuminating pattern is preferably produced by interference of laser light , for which no band limiting optics are needed .
  • a first improvement of image quality is obtained, by subsequently transilluminating over a number of reduced different angular ranges and averaging their light fluxes over the larger angular range that equals the sum of said reduced angular ranges.
  • an improved first image is obtained by lowering contributions of scattered light.
  • Fig.6 illustrates this by a horizontal shift from position "Ml" to "M2", and the associated enlargement of enclosed areas of information density.
  • the larger angular range is illuminated except for the, subsequent, smaller angular ranges. This increases the contributions of scattered light on which a second image signal is based. Successive averaging over the same large angular range favours correlation of noise patterns. Therefore, arithmetic combination of the first and second image signals can provide image signals having reduced image noise .
  • Fig. 7 shows, by way of example, an embodiment of the invention for creating different modes of angular selection ⁇ having multiple light sources that are synchronized with a scanning disk "SD" of the Nipkow type in the pupil plane of the imaging lens.
  • Imaging lenses transfer images that are contained in emulsion Em onto the image sensor .
  • the polarity of the noise pattern reverses at a high scatter ratio.
  • weighed addition of light fluxes from different angular selections reduces image noise when integrated by the image sensor.
  • Fig.8 shows a system for producing different modes of angular selecting, not having moving parts.
  • multiple image sensors each, receive light exclusively from a single, angular range.
  • mirrors in the pupil plane reflect small angular ranges of light to respective image sensors.
  • Fig. 9 shows a system that produces different modes of spatial modulation by illuminating the emulsion with a spatial pattern of a slightly lower frequency than the spatial bandwidth limitation of the imaging system.
  • patterned light sources "A” and “B” are successively, imaged on emulsion "Em” through imaging lens "LI".
  • the patterns in “A” and “B” are of opposite polarity.
  • alternation between "A” and "B” frames are obtained by slightly shifting the modulating light pattern. Furthermore, selection of planes of best focus within the film provides 3-dimensional information if so wanted .
  • Another system is based on polarized illumination together with crossed polarization of light that leaves the emulsion. This increases the scatter ratio. Similarly, parallel polarization decreases the scatter ratio.
  • Fig. 11 shows, by way of example, an embodiment based on polarized illumination by a light source and condenser lens "Co” that illuminates emulsion "Em” which is further imaged by the imaging lens on an image sensor.
  • Ps is a rotating disc with a polarization filter preceding the entrance side of the emulsion
  • Pp is a rotating disc in the light flux that leaves the emulsion and is synchronized to disk "Ps”.
  • One halve of disc “Pp” has its direction of polarization parallel with filter “Ps” ; the other halve has it crossed.
  • Electronic system “EL” modulates the intensity of the light source according to the position of disc “Ps", the position of disk “Pp” and the integration interval of the image sensor in order to create successive image signals of different modes of polarization. All angles of polarization are equally represented if the integration time of the image sensor equals a full number of rotations of the rotating disks.
  • circular polarization can be applied to modify scatter ratios.
  • a left handed circular polarization filter polarizes the illuminating light flux and a right handed circular polarization filter, on the other side of the emulsion, attenuates light that has not been scattered.
  • FIG.12 An embodiment enabling such a combination is shown in fig.12 in which the system of fig. 7 is extended with left handed polarization filter “LH pol” in the illumination path and filters “LH” and “RH” on the scanning disc.
  • Electronic system "EL” selects successive modes of collimation and/or polarization in synchronism with the integration interval of the image sensor and modulates the light source for obtaining adequate signal levels.
  • the relative amount of scattered light by an emulsion depends on the wavelength of illuminating light. Therefore, transilluminating with light of slightly different wavelength provide image signals that relate to slightly different scatter ratios. Subtraction of two of these signals, therefore, produces a modified image signal that, largely, originates from scattered light.
  • the improvements it provides can be further increased in that illumination with structured light and means for subsequent image processing extend the spatial frequency range of the system towards that of the emulsion . In Fig . 6 this would be expressed as a vertical extension of the information area enclosed by "M2" .
  • Multiple systems according to the invention can produce image signals that are determined by di f ferent scatter ratios and are suitable for combined processing and creating one or more improved image signals thereof . Such production or calculation of other image signals is supposed to be part of the invention .

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  • Signal Processing (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
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Abstract

Improved images from photographic emulsions are obtained by inspection of scattered light. Multiple image signals, have different levels of image noise but similar noise patterns. Cancellation of image noise is, therefore, possible. In practical situations, scanning time is not increased. The improvements differ from existing methods in that they are of a fundamental nature that cannot be obtained by image processing.

Description

Title: Method for improved scanning of a photographic emulsion
PRIOR ART
Explanation of the photographic imaging process can be found in :
"IMAGE SCIENCE" by J.C. Dainty and R. Shaw, ISBN 0122008502
It describes the chaotic nature of photographic processes and its effect on film density, modulation transfer and film grain noise to a degree sufficient to understand the problem that the invention means to solve.
-Three dimensional properties of photographic emulsions have been investigated by W.F.Berg as described in :
" The photographic emulsion layer as a three-dimensional Recording Medium"
APPLIED OPTICS December 1969 / Vol. 8 No 12.
It describes to what extent different layers of emulsions contribute to image formation.
-The relation between different types of illumination and image contrast was first reported by A. Callier in:
"Absorption und Diffusion des lichtes in der entwickelten photographischen Platte" Z. wiss. Photogr . Photophys . Photochem. , vol 8 , pp .257-272.
-Further analysis of this callier effect, including its relevance for image noise, is given by: Chavel, P., and Lowenthal, S . in :
"Film grain Noise In partially coherent Imaging" .
SPIE Vol. 194 Application of Optical Coherence (1979)
They express image contrast and noise in relation with angular ranges of transillumination. This relationship leads to:
"the callier surface of contrast".
-Balancing of image noise versus image sharpness by adjustment of illumination has been described by "Terence William Mead of Cintel International Limited" in :
US PAT 8,009,190 B2 (Aug 2011)
-Manipulation of light after transmission through a film is described in:
"Improvements relating to film scanners"
EP0982939A2 (Mead)
-Other methods for obtaining extra information from photographic film are described by Trumpy in :
"Optical detection of Dust and Scratches on Photographic
Film"
ACM Comput . Cult.Herit. 8,2, Article 7 (March 2015) -Illumination over multiple angles has been described by:
Guoan Zheng et. Al. In :
"Microscopy refocusing and dark field imaging by using a simple LED array"
OPTICS LETTERS Vol36, No20 October 15, 2011
-Also known is confocal drum scanning wherein single pixel values are successively generated and most of scattered light does not enter the light path.
-Imaging of spatial frequencies beyond the diffraction limit of lenses has been demonstrated by M.G.L. Gustafsson In:
" Surpassing the lateral resolution limit by a factor of two using structured illumination microscopy" .
Journal of Microscopy / Volume 198, Issue 2 p.82-87
DESCRIPTION
Photographic emulsions contain randomly distributed particles with light absorbing properties. When transilluminated, this chaotic distribution of particles causes unwanted modulation, known as film grain noise. Traditionally, film grain noise is regarded as uncorrectable due to the lack of a fixed pattern for normalization. Although the particles that carry the image information, are chaotically distributed and, therefore, cause film grain noise, they are fixed in a three dimensional constellation. Consequently, the way in which they transmit and scatter light is deterministic by nature and no fundamental law of physics forbids correction of film grain noise as caused by this chaotic distribution of particles .
The present invention aims to retrieve e . g . historic images stored in photographic emulsions with a considerable higher quality than is possible with prior art methods , resulting in fundamentally improved representations of those images .
To that end the present invention provides a method for scanning a photographic emulsion and retrieving an image stored therein and converting the retrieved image into a digital representation, the method comprising the steps of :
Transilluminating the photographic emulsion layer with light having a pre-determined angular distribution and di f ferent modes of angular selection, spatial modulation, polari zation and or wavelength .
-Detecting image signals according to one or more of said di f ferent modes of transillumination .
-Storing two or more of said image signals in an image sensor or processor .
-Producing image signals that originate from, respectively, large and small relative amounts of light that has been scattered by the photographic emulsion .
-Producing an improved image signal thereof .
Figures
The background of the invention will be explained with the aid of figures 1- 6 and di f ferent embodiments will be explained by figures 7- 12 in which : Fig.l shows light ray "L" that enters emulsion "E" and is partly transmitted and scattered.
Fig. 2 shows angular cones of transillumination.
Fig. 3 shows a callier surface of contrast "C" .
Fig. 4 shows a surface of spatial bandwidth "B" versus F- n umber .
Fig. 5 shows Callier ridge "CR" and two more cross sections .
Fig. 6 shows "CR" and "DL" indicating diffraction limitation .
Fig. 7 shows a light path of a system for limiting angular ranges .
Fig. 8 shows a light path for a system without moving parts .
Fig. 9 shows a system for spatial modulation.
Fig.10 shows signals related to the system of fig.9
Fig.11 shows a system having rotating polarization filters.
Fig.12 shows a system having circular polarization filters.
Background of the invention.
Emulsion "E" in fig 1 contains a stack of randomly distributed particles of different sizes, shapes and positions. Light ray "L" transverses this stack of particles partly in a straight line at an angle a, producing transmitted ray "T" and also partly deflected producing scattered light ray "S". Both rays "T" and "S" are subject to attenuation by the particles that carry image information. Scattered light ray "S", may also be subject to multiple deflections, causing it to leave the emulsion with a lateral offset, causing unsharpness. For different angles of incidence, the transmission and scatter values vary to some degree due to the chaotic structure. Likewise, transmission and scatter values also vary with the lateral position. As all pixels are, independently, subject to this process, spatial image noise results.
Therefore, both, spatial image noise and unsharpness depend on the conditions of transillumination.
Fig. 2 shows emulsion "E" being illuminated by a cone of light with angular range Aas which, after leaving the emulsion, is accepted over an angular range Aap. Angular range Aas can be as large as 180 degrees for diffuse illumination, while angular range Aap depends on the imaging system that follows.
The accepted light flux within angular range Aap contains scattered light to a degree expressed by the scatter ratio.
The scatter ratio depends on the type of emulsion, film density and both angles Aas and Aap.
Variability of measured transmission values causes noise modulation "N" proportional to the inverse square root of the solid angular range (Aa)2 of transillumination:
N ~ 1/Aa (1)
Where "Aa" is a general expression for linear angular range . Callier was the first to investigate the effect of diffuse versus specular illumination on image contrast. This "Callier effect" has been quantified and related to film grain noise by Chavel and Lowenthal . This resulted in a surface of Contrast "C" as a function of both angular ranges Aas and Aap. The "callier surface", as shown in Fig.3, has a line of relative high contrast, here, indicated as Callier ridge "CR" .
On line "CR", Aas and Aap are equal. This condition is, also known as having a coherence ratio of 1 or "matched illumination" . The downhill shape of the callier surface is due to scattering of light by particles and depends on film type, film density, grain size, grain shape grain distribution etc.
As scattering of light occurs in all directions, some scattered light also leaves the emulsion with a lateral offset before entering the imaging system. This reduces "image sharpness" or spatial bandwidth: "B" .
The callier surface can be transformed into a meaningful representation of image quality by plotting spatial bandwidth "B" rather than contrast "C" .
The relation between bandwidth "B" and contrast "C" follows from the Modulation Transform Function (MTF) , in that contrast "C" equals MTF at zero spatial frequency and bandwidth "B" equals the frequency at which the MTF has rolled off to a certain degree. Furthermore, we will plot the angular ranges in F-numbers as standardized in photography etc.
In accordance with expression " (1)", this logarithmic scale renders the horizontal coordinates into a value proportional to log (1/N) . In this representation, of spatial bandwidth "B", the area product "I" of its vertical and horizontal coordinates reads as:
1= B x~log(l/N) (2)
Equation (2) represents a relative amount of information density in the sense of Shannon's information theory.
In this context, objective value "I" is meant to be equivalent with "image quality".
Fig.4 shows such a modified callier surface and two practical operating conditions of transillumination.
The first operating point: "D/5, 6" indicates diffuse illumination and an F/5, 6 imaging lens. The second operating point "S/5, 6" indicates specular illumination, also with an F/5, 6 imaging lens.
The line that connects these different illumination conditions represents the variation of diffuse versus specular illumination according to Mead (EP0982939A2 ) .
Fig. 5 shows the callier ridge "CR" of fig.4 as well as the cross sections through the vertical axis and operating points "D/5, 6" and "S/5, 6" respectively. Dotted lines delineate enclosed areas of information density "I".
Maximum image quality is obtained where such an area is maximal, in this example point "M" on "CR" .
Fig. 6 shows Callier ridge "CR" together with curve "DL" which represents spatial bandwidth limitation by diffraction. The spatial bandwidth of the system is, therefore , limited by both curves of which condition "Ml" represents the condition for maximum information density .
Condition "Ml" corresponds to the particular condition of transillumination whereby the maximum density of information can be obtained according to the state of the art .
As shown in figures 4 , 5 and 6 reduction of angular range of transillumination favours a high spatial bandwidth of the emulsion . However, the system bandwidth is also limited by di f fraction as indicated by curve "DL" . This limits overall spatial bandwidth to where the bandwidth of the emulsion equals that of di f fraction .
In Fig . 6 this condition is indicated as "Ml" .
Bandwidth extension beyond the di f fraction limit of microscopes has been reported by M . G . L . Gustafsson and others by illumination with a pattern of a spatial frequency beyond the spatial pass band of a microscope ob j ective .
Such " structured light illumination" , mixes down high spatial frequency components , into the spatial pass band of an imaging lens .
Subsequent image processing trans forms the resulting image signal into an extension of the spatial frequency spectrum . The illuminating pattern is preferably produced by interference of laser light , for which no band limiting optics are needed .
DETAILED DESCRIPTION A first improvement of image quality is obtained, by subsequently transilluminating over a number of reduced different angular ranges and averaging their light fluxes over the larger angular range that equals the sum of said reduced angular ranges. In this mode of angular limiting of light fluxes, an improved first image is obtained by lowering contributions of scattered light.
Fig.6 illustrates this by a horizontal shift from position "Ml" to "M2", and the associated enlargement of enclosed areas of information density.
In an opposite mode of angular selecting, the larger angular range is illuminated except for the, subsequent, smaller angular ranges. This increases the contributions of scattered light on which a second image signal is based. Successive averaging over the same large angular range favours correlation of noise patterns. Therefore, arithmetic combination of the first and second image signals can provide image signals having reduced image noise .
Fig. 7 shows, by way of example, an embodiment of the invention for creating different modes of angular selection^ having multiple light sources that are synchronized with a scanning disk "SD" of the Nipkow type in the pupil plane of the imaging lens.
Here, the programmable light source "PL", subsequentially, illuminates different angular cones of light flux, via condenser "Co" on emulsion "Em". Imaging lenses transfer images that are contained in emulsion Em onto the image sensor . Scanning disc "SD", is meant for rotation in the pupil plane of the imaging lens. Here, openings in "SD", correspond to reduced angular ranges that the programmable light source "PL", illuminates according to the mode of angular selection as chosen.
For some conditions, the polarity of the noise pattern reverses at a high scatter ratio. In such cases, weighed addition of light fluxes from different angular selections reduces image noise when integrated by the image sensor.
Fig.8 shows a system for producing different modes of angular selecting, not having moving parts. Here, multiple image sensors, each, receive light exclusively from a single, angular range. To this end, mirrors in the pupil plane reflect small angular ranges of light to respective image sensors.
Fig. 9 shows a system that produces different modes of spatial modulation by illuminating the emulsion with a spatial pattern of a slightly lower frequency than the spatial bandwidth limitation of the imaging system. To this end, patterned light sources "A" and "B" are successively, imaged on emulsion "Em" through imaging lens "LI". The patterns in "A" and "B" are of opposite polarity.
Spatially modulated images on "Em" are further imaged by imaging lens "L2" onto the image sensor that produces image signals as shown in fig. 10. Synchronized demodulation by the image processor separates modulated from average signal. As light, that has been scattered by the emulsion, contributes more to the average signal and less to the modulation, signals relating to different scatter ratios are obtained. Fig 10 shows how alternating "A" and "B" frames provide signals from which unwanted components are cancelled.
In this embodiment, alternation between "A" and "B" frames are obtained by slightly shifting the modulating light pattern. Furthermore, selection of planes of best focus within the film provides 3-dimensional information if so wanted .
Another system is based on polarized illumination together with crossed polarization of light that leaves the emulsion. This increases the scatter ratio. Similarly, parallel polarization decreases the scatter ratio.
As each angle of polarization comes with unrelated image noise, all or almost all angles of polarization are represented for noise reduction by averaging.
Fig. 11 shows, by way of example, an embodiment based on polarized illumination by a light source and condenser lens "Co" that illuminates emulsion "Em" which is further imaged by the imaging lens on an image sensor. "Ps" is a rotating disc with a polarization filter preceding the entrance side of the emulsion, while "Pp" is a rotating disc in the light flux that leaves the emulsion and is synchronized to disk "Ps". One halve of disc "Pp" has its direction of polarization parallel with filter "Ps" ; the other halve has it crossed. Electronic system "EL" modulates the intensity of the light source according to the position of disc "Ps", the position of disk "Pp" and the integration interval of the image sensor in order to create successive image signals of different modes of polarization. All angles of polarization are equally represented if the integration time of the image sensor equals a full number of rotations of the rotating disks.
Furthermore, circular polarization can be applied to modify scatter ratios. For instance, a left handed circular polarization filter polarizes the illuminating light flux and a right handed circular polarization filter, on the other side of the emulsion, attenuates light that has not been scattered.
This increases the scatter ratio and , similarly, an evenhanded filter decreases the scatter ratio. Because of rotational symmetry, there is no need, here, for rotating the filters.
This type of modification of scatter ratios by circular polarization is easily, but not necessarily, combined with a system based on angular selecting.
An embodiment enabling such a combination is shown in fig.12 in which the system of fig. 7 is extended with left handed polarization filter "LH pol" in the illumination path and filters "LH" and "RH" on the scanning disc. Electronic system "EL" selects successive modes of collimation and/or polarization in synchronism with the integration interval of the image sensor and modulates the light source for obtaining adequate signal levels.
As described by Dainty and Shaw, the relative amount of scattered light by an emulsion depends on the wavelength of illuminating light. Therefore, transilluminating with light of slightly different wavelength provide image signals that relate to slightly different scatter ratios. Subtraction of two of these signals, therefore, produces a modified image signal that, largely, originates from scattered light. According to the invention, the improvements it provides can be further increased in that illumination with structured light and means for subsequent image processing extend the spatial frequency range of the system towards that of the emulsion . In Fig . 6 this would be expressed as a vertical extension of the information area enclosed by "M2" .
Multiple systems according to the invention can produce image signals that are determined by di f ferent scatter ratios and are suitable for combined processing and creating one or more improved image signals thereof . Such production or calculation of other image signals is supposed to be part of the invention .

Claims

CLAIMS Method for scanning a photographic film having an emulsion and retrieving an image stored therein and converting the retrieved image into a digital representation, the method comprising : transilluminating the photographic emulsion layer with light having pre-determined integral spatial angular distributions of light , on entering and leaving the emulsion, and subsequent selecting multiple angular ranges thereof whereby the summations of the angular selections correspond to the respective integral spatial angular distributions characteri zed in tha t the summations of the angular selections contain di f ferent amounts of light that has been scattered by the photographic emulsion and detecting of image signals that result from these transilluminations . Method for scanning a photographic film having an emulsion and retrieving an image stored therein and converting the retrieved image into a digital representation, the method comprising : transilluminating the photographic emulsion layer with light having pre-determined spatial angular distributions and spatial modulating, modulating of wavelength and/or polari zation and producing image signals there-of characteri zed in tha t these image signals relate to di f ferent relative amounts of light that has been scattered by the photographic emulsion . Storing and processing of image signals that have been obtained according to claim ( 1 ) or ( 2 ) , characteri zed by arithmetically combining these signals into an image signal with reduced image noise.
5
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0982939A2 (en) 1998-08-21 2000-03-01 Cintel International Limited Improvements relating to film scanners
US20030197901A1 (en) * 2002-04-22 2003-10-23 Pentax Corporation Film scanner
US20050219518A1 (en) * 2002-09-30 2005-10-06 Doron Korngut Dark field inspection system
US20070263226A1 (en) * 2006-05-15 2007-11-15 Eastman Kodak Company Tissue imaging system
US8009190B2 (en) 2005-09-06 2011-08-30 Cintel International Limited Optical scatter correction for film scanners

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0982939A2 (en) 1998-08-21 2000-03-01 Cintel International Limited Improvements relating to film scanners
US20030197901A1 (en) * 2002-04-22 2003-10-23 Pentax Corporation Film scanner
US20050219518A1 (en) * 2002-09-30 2005-10-06 Doron Korngut Dark field inspection system
US8009190B2 (en) 2005-09-06 2011-08-30 Cintel International Limited Optical scatter correction for film scanners
US20070263226A1 (en) * 2006-05-15 2007-11-15 Eastman Kodak Company Tissue imaging system

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* Cited by examiner, † Cited by third party
Title
"Application of Optical Coherence", SPIE, vol. 194, 1979
"The photographic emulsion layer as a three-dimensional Recording Medium", APPLIED OPTICS, vol. 8, no. 12, December 1969 (1969-12-01)
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