CA2416178A1 - Process and apparatus for the manufacture of a photographic print - Google Patents
Process and apparatus for the manufacture of a photographic print Download PDFInfo
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- CA2416178A1 CA2416178A1 CA 2416178 CA2416178A CA2416178A1 CA 2416178 A1 CA2416178 A1 CA 2416178A1 CA 2416178 CA2416178 CA 2416178 CA 2416178 A CA2416178 A CA 2416178A CA 2416178 A1 CA2416178 A1 CA 2416178A1
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Abstract
Optical representations of differing strip-shaped portions of an original are successively produced by way of an electro-optical converter operating pixel-by-pixel for the manufacture of a photographic print from an original present in electronic form. The optical representations are exposed onto the copy material in a strip-shaped exposure region, whereby the strip-shaped exposure region and the copy material are moved relative to one another at a constant speed and in a direction transverse to the longitudinal extent of the strip-shaped exposure region. In this way, the image information of the whole original is successively exposed onto the whole available surface of the copy material. A digital micro mirror array is preferably used as the electro-optical converter. The electro-optical converter is positioned in the exposure light path in such a way that its rows and columns extend at an angle of essentially 45E to the longitudinal extent of the strip shaped exposure region. A strip-shaped pixel region of the converter oriented essentially in the diagonal of the converter is thereby used for the production of the optical reproductions of the step-shaped portions of the original. Thus, the strip-shaped optical image representation of the strip-shaped portions of the original extend along the diagonal of the converter, which results in a higher resolution for the same converter since a larger number of pixels are available for production of the same image. Larger print formats can be achieved with commercially available converters and substantially without a loss in quality.
Description
PROCESS AND APPARATUS FOR THE MANUF.A(.'TLTRE OF A
PHOTOGRAPHIC PRIl~T
FIELD OF THE INVENTION
The invention relates to a process and appalrat:us for the manufacture of a photographic print, especially a copy of an original present in electronic form, by strip-wise exposure of the image information ohthe original onto a photographic copy material.
BACKGROUND ART
Digital print producing apparatus on photographic basis, so called digital photographic printers, produce prints or copies by exposure of the image information of the underlying original stored in electronic form onto a photosensitive copy material. One possibility herefore consists in that the image information of the original is image;-wise optically reproduced by way of a suitable electro-optical converter operating pixel-by-pixel to produce an optical representation of the original, and to project this optical representation of the original onto the copy material to thereby expose it thereon. Suitable electro-optical converters can thereby be acti~.~e (self illuminating) as well as passive (modulating) electro-optical arrangements.
Typical examples are cathode ray tubes, liquid crystal cell arrays operated in transmission or reflection, light-emitting diode arrays, electro-luminescence cell arrays and lately also so-called digital micro mirror arrays.
One of the deciding factors for the quality of photographic prints or copies produced in this way is the resolution (pixel number) of the electro-optical converter used. While sufficiently highly resolving small converters are available at economically acceptable prices, the development of economically producible and commercially useful large surface converters of corresponding resolution is still in its beginnings. Thus, only relatively small forniat prints can be produced with satisfactory quality with the available converters.
Theoretically, photographic prints of any sizf:. can be produced by line by line or strip wise exposure in direction transverse to the lines or strips. Only strip-shaped portions of the original which in their longitudinal direction cover the whole original are hereby successively optically reproduced by way of the converter and successively exposed in a corresponding spatial relationship onto the copy material.
The correct spatial positioning of the exposed strips is thereby achieved by displacement of the copy material relative to the exposure light path. The latter can be achieved by an advance of the copy material or by a correspondingly moveable imaging optic. The relative displacement is of course carried out synchronously with the change of the exposed strips of the onginal. If the strips are several lines wide, neighboring strips can also overlap. Since; the copy material is thereby multiply exposed depending on the degree of overlap, this must be correspondingly considered for the adjustment of the amount o.f copy light in the individual exposure steps. This exposure process is generally known under the term TIG (tine integration gray scale).
Comparatively cheap linear converters can be used for this process of the line or strip wise exposure. Rectangular converter element arrangements (arrays) are understood hereunder, the width of whioh is significantly smaller than the length. In the extreme case, such a linear converter has only a sin<~le row (line) of converter elements, typically however up to several hundred rows. Ln longitudinal direction (per row or line] such a linear converter in contrast typically includes 1,000 or more converter elements. Of course, wider converters (with a higher number of rows) can also be used, whereby not all rows (which means not the whole width) need be used.
With the above described methods, qualitatively satisfactory photographic prints can only be manufactured with commercially available converters when the format of the print to be produced in longitudinal direction of the exposed strips is relatively small. However, for larger image formats in the other dimension, the resolution of the commercially available and economically acceptable converters is in many cases insufficient.
EP-A-0 9~6 243 discloses an improved process in which the resolution of the produced photographic print is achieved by a lengthwise division of the individual strip-shaped portions of the original into two or more sections and by a con~esponding piece-wise exposure. Since the Full length of the converter is hareby respectively only used for the reproduction of a section, a doubling or multiplying of the resolution results - in longitudinal direction of the ships - according to the number of sections, so that very large format images of satisfactory quality can be produced even with conventional converters.
SU11~IMARY OF THE INVENTION
It is an object of the invention to now provide an alternative approach for improving a process and an apparatus in such a way that larger format images can be produced with satisfactory quality in an economical mariner without large additional technical cost. In particular, this object is preferably achieved using commercially available and economically acceptable converters, which means no special, higher resolution or larger, and correspondingly more expensive, converters should be required.
This object of the invention is achieved in an apparatus for the production of a photographic print from an original present in electronic form by strip-wise exposure of the image information of the original onto a photo;~rraphic copy material, including a memory for receiving the image information of the original, an electz-o-optical converter operating pixel-by-pixel and organized into orthogonal rows and colurrms and an associated control for generating an optical representation of strip-shaped portions of the original stored in the memory, with a projection optic for projecting the optical representations of the strip-shaped portions in a strip-shaped exposure region onto the copy material, and with drive-means for moving the strip-shaped exposure region and the copy material with essentially constant speed in a direction transverse to the longitudinal extent of the strip-shaped exposure region and relative to one another.
According to the invention, this object is achieved by rotating the con~~erter in the exposure light path by 45E so that the strip-shaped optical image representation of the strip-shaped portions of the original extends along tine diagonal (of the usable region) of the optical converter. By way of this rotated orientation of the optical converter in accordance with the invention, a by a factor of 2'i= (~l .4) higher resolution results in both dimensions compared to the classical arrangement and thereby the possibility to achieve larger print foumais with conventional, commercially available converters without a loss in quality.
BRIEF DESCRIPTION OF 'THE DR~~'I:NGS
The invention will now be further described by way of example only and with reference to the attached drawings, wherein Figures 1-3 respectively illustrate a schematical illustration ofthe generally known principle of the strip-shaped exposure also used in the process in accordance with the invention;
Figures 4 and ~ shorn two schematic illustrations of the process in accordance with the invention; and Figure 6 is a schematical illustratiotr of the apparatus in accordance with the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following is based on the asswnption that the original of which a physical photographical print or copy is to be made is present in electronically stored format.
The image information composed of the totality of ali brightness and color information for each individual image point of the original to be copied is thereby stored in a memory 1 (see Figure 6j from which it can be recal led pixel-by-pixel and possibly separated according to color proportions by way of a control 2 (see Figure 6).
,analogously, the image information of a strip shaped portion of the origilzal is understood to represent the totality of the brightness and color information of'those image points of the original which belong to the corresponding strip-shaped portion of the original.
Figures I-3 illustrate the principal of the line-by-line or strip-wise exposure known, for example, from EP-A-O 986 ~43 and described in great detail therein.
The original represented by the totality of all stored brightness and color information for each individual one of its pixels is referred to by ~'. The control apparent from Figure 6 reads out the image information of a first strip-shaped portion A of the original V
and controls thereby a pixel by pixel operating electro-optical converter ~, which produces on the basis of the signals received an optical image representation D of the strip-shaped portion A. The elec.tro-optical converter 3 can, for example. be formed by a light-emitting diode array with, for example, 1230 x X00 individual diodes or prel:erably, as further described below, by a digital micro-mirror array with a corresponding or larger number of individual mirror<.~. The also strip-shaped optical representation D of the strip-shaped portion A of the original ~' produced by the electro-optical converter 3 is now projected by way of a here not illustrated projection optic in a (in this example stationary) strip-shaped exposure region E onto a photographic photographic copy material P and ther;.by exposed thereonto (Figure 1 ).
Subsequently, the next strip-shaped portion AN is read out, an optical representation DN is produced therefrom and the latter exposed onto the copy mater ial P (Fi lure ? ) which was simultaneously advanced by a corresponding distance relative to the exposure region E. This whole process is now repeated until the whole original has peen captured and the last strip shaped porrtion ANN of the original was read out, an optical representation DNN was produced therefrom and the latter was exposed onto the copy material P (Figure 3).
As is apparent, the strip-shaped portions A of the original do not lie seamlessly side-by-side, but overlap one another to a large de~-ee (transverse to their .longitudinal direction). This results in that the strips exposed onto the copy material P
also overlap, so that the copy material P is multiply exposed depending on the degree of overlap.
This multiple exposure is taken into consideration in that the brightness values of the individual pixels of the optical representations D of the portions A are correspondingly reduced by the control (possibly c:.olor selective) so that the sum of the copy light amounts impacting the copy material at the respective image points are again correct. This exposure method is known under the term TIG (time integration gray scale).
As already mentioned, it is necessary for the :grip-wise exposure that a relative movement occurs between the strip-shaped exposure region E and the copy material P. This is achieved in the above example by a cortesponding advance of the copy material P. Alternatively, and especially practically, the relative movement can also be achieved by a moveable construction of the projection optic, whereby the copy material remains stationary during the whole exposure. The principal of such a moveable exposure optic is apparent from Figure 6 and dese.ribed in detail in the already mentioned EP-A-0 986 243.
The electro-optical converter 3 caa~ principally be any active or passive type converter operating pixel-by-pixel. Examples are, as already mentioned, cathode ray tubes, light emitting diode arrays, electro-luminescence arrays or liduid crystal arrays.
However, especially advantageous are so-called digital micro-mirror ~Lrrays (DMD =
digital mirror device), as are used, for example, also in large image projection apparatus. A typical digital micro-mirror array suitable for the purpose of the invention includes on one chip an array of 1280 ~ 1024 mirrors, which can be selectively flipped back and forth by electneal control between two defined tilt positions.
Such micro-mirror arrays are natw-ally operated in reflection, which means they are passive. In practical use, as also apparent from Figure (> algid illustrated and described in detail in the already mentioned EP-.A-0 986 243, they are positioned in such a way in front of the pupil of a projection Tans that the micro-mirrors direct the light impinging thereon in the first tilt position directly into the projection lens and in the other tilt position past the pupil of the projection lens. The intensity modulation of the reflected light is thereby carried out on the basis of the stored image information of the original by intermittent operation of the micro-mirrors with a corresponding duty cycle. Construction, control technologies and possible uses of such micro-mirror an-ays are described in detail in the relevant publications of the manufacturer companies, for example the company Texas Instruments, Houston, Texas, U.S_A., and are not the subject of the present invention.
Up to this point, the process in accordance with the invezotion corresponds to the prior art and therefore does not require any further explanation.
As is apparent, the length of the strip-shaped portions .A which cover the whole width of the original comespomds in the conventional process to the length (of the useful surface) of the electro-optical converter 3. The resolution in longitudinal direction of the strip is therefore deterniined by the number of the individual pixels of the converter 3. However, the resolution achievable at larger enlargement scales (large format pictures) is in many cases qualitatively insufficient. This is where the invention starts.
According to the most basic object of t:he invention, the converter 3, as illustrated in Figure 4, is positioned in the projection 1ig11t path in a 4~E
rotated orientation so that the strip-shaped optical image representation D of the strip-shaped portions A of the original V are orientated in the. diagonal (of the usable region) of the optical converter 3. In other words, not a rectanguhu- pixel region of the converter 3 defined by a certain number of~who(e lines is used for the image conversion, but a pixel region which essentially W eludes all available rows, but thereby uses only a pat-t of the available pixels from each roc~-~, so That the pixels used for the representation together cover a strip-shaped region ~~hich lies in the diagonal of the converter. This is illustrated in Figure ~.
The rotated position in accordance with the invention of the optical converter 3, results, compared to the classical positioning, in a resolution, which in both dimensions is by about a factor of 2'r'_> (~-1.41 higher. For example, for a commercially available converter with 1024 rows of 1280 pixels each, a reproduction region D
results ~rith 192 rows of 1919 pixel each. When tl~e projection region is of lesser height (which means with less rows), the number of usable pixels per row is even higher.
As is illustrated in Figure ~, the imaging region D of the converter 3 strictly speaking is not rectangular for the image wise reproduction of the strip-shaped portions A of the original V, but has the shape of an elongated parallelogram ~lhicll is composed of individual rectangles. However, for the generally common use of the TIG exposure method (time integration gray scale) this is not important.
With the rotated orientation of the optical converter 3 in accordance with the invention, the transport direction (direction of the relative movement between the strip-shaped exposure region E and the copy material P) is of course also rotated by 45E relative to the rows of the optical converter 3. The parallelogram shape of the pixel region used for the image reproduction, the location of the pixel used on the usable surface of the converter and the transport direction rotated by 45E
require a somewhat more involved control of the individual pixels of the cormerier, but is readily understood and realizable by ~he person skilled in the art.
A principal schematic of the apparatus in accordance with the invention is shown in Figure 6. The apparatus includes the already mentioned memory 1 and the already mentioned control 2 as well as an illumination source 4, the already mentioned converter 3 in the form of a micro-mirror array, an imaging optic consisting of a Lens 5 and 3 redirecting mirrors 6, ',' and 8. and drive means symbolized by arrows 9a to 9c for the redirecting mirrors and the lens. The two redirecting mirrors 6 and ? are stationary relative io one another and are at a right angle to one another so that they redirect the beam by 180E. The redirecting mirror 8 is positioned parallel to the redirecting mirror ? and redirects the beam by 90Eonto the copy material P. The redirecting minor 8 moves in the same direction as the two redirecting mirrors 6 and 7 but with twice the speed to that the optical distance between the Iens and the copy material P remains constant independent of the position of the redirecting mirrors. The strip-shaped exposure region E is moved over the (stationary) copy material P by the movement of the redirecting mirrors in the manner described. By adjustment of the lens 5 in combination with a corresponding adjustment of the redirecting mirrors 6 to e, the reproduction scale can be changed.
Vvith the exception of the positioning of the micro-mirror array 3 rotated by 4~E, the apparatus completely corresponds to the apparatus described, for example, in the already mentioned EP-A-0 986 243, and therefore does not require any further explanation. Of course, the control is correspondingly adapted.
By way of the higher resolution achieved in accordance with the invention, large format pictures of satisfactory quality can be produced 4~~ithout large additional technical cost and in an economical manner. This is possible especially with the use of commercially available and economic<dly acceptable converters, which means no special, higher resolution or larger and correspondingly more expensive converters are required.
PHOTOGRAPHIC PRIl~T
FIELD OF THE INVENTION
The invention relates to a process and appalrat:us for the manufacture of a photographic print, especially a copy of an original present in electronic form, by strip-wise exposure of the image information ohthe original onto a photographic copy material.
BACKGROUND ART
Digital print producing apparatus on photographic basis, so called digital photographic printers, produce prints or copies by exposure of the image information of the underlying original stored in electronic form onto a photosensitive copy material. One possibility herefore consists in that the image information of the original is image;-wise optically reproduced by way of a suitable electro-optical converter operating pixel-by-pixel to produce an optical representation of the original, and to project this optical representation of the original onto the copy material to thereby expose it thereon. Suitable electro-optical converters can thereby be acti~.~e (self illuminating) as well as passive (modulating) electro-optical arrangements.
Typical examples are cathode ray tubes, liquid crystal cell arrays operated in transmission or reflection, light-emitting diode arrays, electro-luminescence cell arrays and lately also so-called digital micro mirror arrays.
One of the deciding factors for the quality of photographic prints or copies produced in this way is the resolution (pixel number) of the electro-optical converter used. While sufficiently highly resolving small converters are available at economically acceptable prices, the development of economically producible and commercially useful large surface converters of corresponding resolution is still in its beginnings. Thus, only relatively small forniat prints can be produced with satisfactory quality with the available converters.
Theoretically, photographic prints of any sizf:. can be produced by line by line or strip wise exposure in direction transverse to the lines or strips. Only strip-shaped portions of the original which in their longitudinal direction cover the whole original are hereby successively optically reproduced by way of the converter and successively exposed in a corresponding spatial relationship onto the copy material.
The correct spatial positioning of the exposed strips is thereby achieved by displacement of the copy material relative to the exposure light path. The latter can be achieved by an advance of the copy material or by a correspondingly moveable imaging optic. The relative displacement is of course carried out synchronously with the change of the exposed strips of the onginal. If the strips are several lines wide, neighboring strips can also overlap. Since; the copy material is thereby multiply exposed depending on the degree of overlap, this must be correspondingly considered for the adjustment of the amount o.f copy light in the individual exposure steps. This exposure process is generally known under the term TIG (tine integration gray scale).
Comparatively cheap linear converters can be used for this process of the line or strip wise exposure. Rectangular converter element arrangements (arrays) are understood hereunder, the width of whioh is significantly smaller than the length. In the extreme case, such a linear converter has only a sin<~le row (line) of converter elements, typically however up to several hundred rows. Ln longitudinal direction (per row or line] such a linear converter in contrast typically includes 1,000 or more converter elements. Of course, wider converters (with a higher number of rows) can also be used, whereby not all rows (which means not the whole width) need be used.
With the above described methods, qualitatively satisfactory photographic prints can only be manufactured with commercially available converters when the format of the print to be produced in longitudinal direction of the exposed strips is relatively small. However, for larger image formats in the other dimension, the resolution of the commercially available and economically acceptable converters is in many cases insufficient.
EP-A-0 9~6 243 discloses an improved process in which the resolution of the produced photographic print is achieved by a lengthwise division of the individual strip-shaped portions of the original into two or more sections and by a con~esponding piece-wise exposure. Since the Full length of the converter is hareby respectively only used for the reproduction of a section, a doubling or multiplying of the resolution results - in longitudinal direction of the ships - according to the number of sections, so that very large format images of satisfactory quality can be produced even with conventional converters.
SU11~IMARY OF THE INVENTION
It is an object of the invention to now provide an alternative approach for improving a process and an apparatus in such a way that larger format images can be produced with satisfactory quality in an economical mariner without large additional technical cost. In particular, this object is preferably achieved using commercially available and economically acceptable converters, which means no special, higher resolution or larger, and correspondingly more expensive, converters should be required.
This object of the invention is achieved in an apparatus for the production of a photographic print from an original present in electronic form by strip-wise exposure of the image information of the original onto a photo;~rraphic copy material, including a memory for receiving the image information of the original, an electz-o-optical converter operating pixel-by-pixel and organized into orthogonal rows and colurrms and an associated control for generating an optical representation of strip-shaped portions of the original stored in the memory, with a projection optic for projecting the optical representations of the strip-shaped portions in a strip-shaped exposure region onto the copy material, and with drive-means for moving the strip-shaped exposure region and the copy material with essentially constant speed in a direction transverse to the longitudinal extent of the strip-shaped exposure region and relative to one another.
According to the invention, this object is achieved by rotating the con~~erter in the exposure light path by 45E so that the strip-shaped optical image representation of the strip-shaped portions of the original extends along tine diagonal (of the usable region) of the optical converter. By way of this rotated orientation of the optical converter in accordance with the invention, a by a factor of 2'i= (~l .4) higher resolution results in both dimensions compared to the classical arrangement and thereby the possibility to achieve larger print foumais with conventional, commercially available converters without a loss in quality.
BRIEF DESCRIPTION OF 'THE DR~~'I:NGS
The invention will now be further described by way of example only and with reference to the attached drawings, wherein Figures 1-3 respectively illustrate a schematical illustration ofthe generally known principle of the strip-shaped exposure also used in the process in accordance with the invention;
Figures 4 and ~ shorn two schematic illustrations of the process in accordance with the invention; and Figure 6 is a schematical illustratiotr of the apparatus in accordance with the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following is based on the asswnption that the original of which a physical photographical print or copy is to be made is present in electronically stored format.
The image information composed of the totality of ali brightness and color information for each individual image point of the original to be copied is thereby stored in a memory 1 (see Figure 6j from which it can be recal led pixel-by-pixel and possibly separated according to color proportions by way of a control 2 (see Figure 6).
,analogously, the image information of a strip shaped portion of the origilzal is understood to represent the totality of the brightness and color information of'those image points of the original which belong to the corresponding strip-shaped portion of the original.
Figures I-3 illustrate the principal of the line-by-line or strip-wise exposure known, for example, from EP-A-O 986 ~43 and described in great detail therein.
The original represented by the totality of all stored brightness and color information for each individual one of its pixels is referred to by ~'. The control apparent from Figure 6 reads out the image information of a first strip-shaped portion A of the original V
and controls thereby a pixel by pixel operating electro-optical converter ~, which produces on the basis of the signals received an optical image representation D of the strip-shaped portion A. The elec.tro-optical converter 3 can, for example. be formed by a light-emitting diode array with, for example, 1230 x X00 individual diodes or prel:erably, as further described below, by a digital micro-mirror array with a corresponding or larger number of individual mirror<.~. The also strip-shaped optical representation D of the strip-shaped portion A of the original ~' produced by the electro-optical converter 3 is now projected by way of a here not illustrated projection optic in a (in this example stationary) strip-shaped exposure region E onto a photographic photographic copy material P and ther;.by exposed thereonto (Figure 1 ).
Subsequently, the next strip-shaped portion AN is read out, an optical representation DN is produced therefrom and the latter exposed onto the copy mater ial P (Fi lure ? ) which was simultaneously advanced by a corresponding distance relative to the exposure region E. This whole process is now repeated until the whole original has peen captured and the last strip shaped porrtion ANN of the original was read out, an optical representation DNN was produced therefrom and the latter was exposed onto the copy material P (Figure 3).
As is apparent, the strip-shaped portions A of the original do not lie seamlessly side-by-side, but overlap one another to a large de~-ee (transverse to their .longitudinal direction). This results in that the strips exposed onto the copy material P
also overlap, so that the copy material P is multiply exposed depending on the degree of overlap.
This multiple exposure is taken into consideration in that the brightness values of the individual pixels of the optical representations D of the portions A are correspondingly reduced by the control (possibly c:.olor selective) so that the sum of the copy light amounts impacting the copy material at the respective image points are again correct. This exposure method is known under the term TIG (time integration gray scale).
As already mentioned, it is necessary for the :grip-wise exposure that a relative movement occurs between the strip-shaped exposure region E and the copy material P. This is achieved in the above example by a cortesponding advance of the copy material P. Alternatively, and especially practically, the relative movement can also be achieved by a moveable construction of the projection optic, whereby the copy material remains stationary during the whole exposure. The principal of such a moveable exposure optic is apparent from Figure 6 and dese.ribed in detail in the already mentioned EP-A-0 986 243.
The electro-optical converter 3 caa~ principally be any active or passive type converter operating pixel-by-pixel. Examples are, as already mentioned, cathode ray tubes, light emitting diode arrays, electro-luminescence arrays or liduid crystal arrays.
However, especially advantageous are so-called digital micro-mirror ~Lrrays (DMD =
digital mirror device), as are used, for example, also in large image projection apparatus. A typical digital micro-mirror array suitable for the purpose of the invention includes on one chip an array of 1280 ~ 1024 mirrors, which can be selectively flipped back and forth by electneal control between two defined tilt positions.
Such micro-mirror arrays are natw-ally operated in reflection, which means they are passive. In practical use, as also apparent from Figure (> algid illustrated and described in detail in the already mentioned EP-.A-0 986 243, they are positioned in such a way in front of the pupil of a projection Tans that the micro-mirrors direct the light impinging thereon in the first tilt position directly into the projection lens and in the other tilt position past the pupil of the projection lens. The intensity modulation of the reflected light is thereby carried out on the basis of the stored image information of the original by intermittent operation of the micro-mirrors with a corresponding duty cycle. Construction, control technologies and possible uses of such micro-mirror an-ays are described in detail in the relevant publications of the manufacturer companies, for example the company Texas Instruments, Houston, Texas, U.S_A., and are not the subject of the present invention.
Up to this point, the process in accordance with the invezotion corresponds to the prior art and therefore does not require any further explanation.
As is apparent, the length of the strip-shaped portions .A which cover the whole width of the original comespomds in the conventional process to the length (of the useful surface) of the electro-optical converter 3. The resolution in longitudinal direction of the strip is therefore deterniined by the number of the individual pixels of the converter 3. However, the resolution achievable at larger enlargement scales (large format pictures) is in many cases qualitatively insufficient. This is where the invention starts.
According to the most basic object of t:he invention, the converter 3, as illustrated in Figure 4, is positioned in the projection 1ig11t path in a 4~E
rotated orientation so that the strip-shaped optical image representation D of the strip-shaped portions A of the original V are orientated in the. diagonal (of the usable region) of the optical converter 3. In other words, not a rectanguhu- pixel region of the converter 3 defined by a certain number of~who(e lines is used for the image conversion, but a pixel region which essentially W eludes all available rows, but thereby uses only a pat-t of the available pixels from each roc~-~, so That the pixels used for the representation together cover a strip-shaped region ~~hich lies in the diagonal of the converter. This is illustrated in Figure ~.
The rotated position in accordance with the invention of the optical converter 3, results, compared to the classical positioning, in a resolution, which in both dimensions is by about a factor of 2'r'_> (~-1.41 higher. For example, for a commercially available converter with 1024 rows of 1280 pixels each, a reproduction region D
results ~rith 192 rows of 1919 pixel each. When tl~e projection region is of lesser height (which means with less rows), the number of usable pixels per row is even higher.
As is illustrated in Figure ~, the imaging region D of the converter 3 strictly speaking is not rectangular for the image wise reproduction of the strip-shaped portions A of the original V, but has the shape of an elongated parallelogram ~lhicll is composed of individual rectangles. However, for the generally common use of the TIG exposure method (time integration gray scale) this is not important.
With the rotated orientation of the optical converter 3 in accordance with the invention, the transport direction (direction of the relative movement between the strip-shaped exposure region E and the copy material P) is of course also rotated by 45E relative to the rows of the optical converter 3. The parallelogram shape of the pixel region used for the image reproduction, the location of the pixel used on the usable surface of the converter and the transport direction rotated by 45E
require a somewhat more involved control of the individual pixels of the cormerier, but is readily understood and realizable by ~he person skilled in the art.
A principal schematic of the apparatus in accordance with the invention is shown in Figure 6. The apparatus includes the already mentioned memory 1 and the already mentioned control 2 as well as an illumination source 4, the already mentioned converter 3 in the form of a micro-mirror array, an imaging optic consisting of a Lens 5 and 3 redirecting mirrors 6, ',' and 8. and drive means symbolized by arrows 9a to 9c for the redirecting mirrors and the lens. The two redirecting mirrors 6 and ? are stationary relative io one another and are at a right angle to one another so that they redirect the beam by 180E. The redirecting mirror 8 is positioned parallel to the redirecting mirror ? and redirects the beam by 90Eonto the copy material P. The redirecting minor 8 moves in the same direction as the two redirecting mirrors 6 and 7 but with twice the speed to that the optical distance between the Iens and the copy material P remains constant independent of the position of the redirecting mirrors. The strip-shaped exposure region E is moved over the (stationary) copy material P by the movement of the redirecting mirrors in the manner described. By adjustment of the lens 5 in combination with a corresponding adjustment of the redirecting mirrors 6 to e, the reproduction scale can be changed.
Vvith the exception of the positioning of the micro-mirror array 3 rotated by 4~E, the apparatus completely corresponds to the apparatus described, for example, in the already mentioned EP-A-0 986 243, and therefore does not require any further explanation. Of course, the control is correspondingly adapted.
By way of the higher resolution achieved in accordance with the invention, large format pictures of satisfactory quality can be produced 4~~ithout large additional technical cost and in an economical manner. This is possible especially with the use of commercially available and economic<dly acceptable converters, which means no special, higher resolution or larger and correspondingly more expensive converters are required.
Claims (13)
1. A process for the production of a photographic print from an original present in electronic form, comprising the steps of successively generating optical representations of image information in different strip-shaped portions of the original by way of an electro-optical converter operating pixel-by-pixel and organized into orthogonal rows and columns; projecting the optical representations in a strip-shaped exposure region onto the copy material;
moving the strip-shaped exposure region and the copy material relative to one another at an essentially constant speed and in a direction transverse to the longitudinal extent of the strip-shaped exposure region for successively exposing the image information of the whole original onto the whole available surface of the copy material; and orienting the exposure light path in such a way that the longitudinal extent of the strip-shaped exposure region is essentially at an angle of 45E relative to the rows and columns of the electro-optical converter.
moving the strip-shaped exposure region and the copy material relative to one another at an essentially constant speed and in a direction transverse to the longitudinal extent of the strip-shaped exposure region for successively exposing the image information of the whole original onto the whole available surface of the copy material; and orienting the exposure light path in such a way that the longitudinal extent of the strip-shaped exposure region is essentially at an angle of 45E relative to the rows and columns of the electro-optical converter.
2. Process according to claim 1 wherein the step of producing the optical representation of the strip-shaped sections of the original is carried out with a strip-shaped pixel region of the converter extending essentially along the diagonal of the converter.
3. Process according to claim 2, wherein a a pixel region with about 1900 x pixel of a converter with pixels arranged in about 1024 rows and 1280 columns is used.
4. Process according to claim 1, wherein the step of moving the strip-shaped exposure region relative to the copy material includes the step of using a movable projection optic for redirecting the exposure light path.
5. Process according to claim 1, wherein the step of moving the strip-shaped exposure region relative to the copy material includes the step of maintaining the electro-optical converter and the copy material stationary and the step of using a mirror arrangement movable parallel to the copy material for redirecting the exposure light path.
6. Process according to claim 1, wherein the step of producing the optical representations of the strip-shaped portions of the original includes the step of using a digital micro mirror array.
7. Apparatus for the production of a photographic print from an original present in electronic form by strip-wise exposure of the image information of the original onto a photographic copy material, comprising a memory for receiving the image information of the original, an electro-optical converter operating pixel-by-pixel and organized into orthogonal rows and columns, and an associated control for generating an optical representation of strip-shaped portions of the original stored in the memory. a projection optic for projecting the optical representations of the strip-shaped portions onto a strip-shaped exposure region on the copy material, and drive-means for moving the strip-shaped exposure region and the copy material relative to one another and at an essentially constant speed in a direction transverse to the longitudinal extent of the strip-shaped exposure region, the electro-optical converter being positioned in the exposure light path in such a way that its rows and columns extend at an angle of inclination of 45E relative to the longitudinal extent of the strip shaped exposure region.
8. Apparatus according to claim 7, wherein the electro-optical converter is a digital micro mirror array.
9. Apparatus according to claim 8, whereby the control for the production of the optical representations of the strip-shaped portions of the original controls a strip-shaped pixel region of the converter extending in the; diagonal of the converter.
10. Apparatus according to claim 7, wherein the projection optic has a movable mirror arrangement for generating the relative movement between the strip-shaped exposure region and the copy material.
11. Apparatus according to claim 8, wherein the projection optic has a movable mirror arrangement for generating the relative: movement between the strip-shaped exposure region and the copy material.
12. Apparatus according to claim 9, wherein the projection optic has a movable mirror arrangement for generating the relative movement between the strip-shaped exposure region and the copy material.
13
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH02000265.5 | 2002-01-15 | ||
| CH2652002 | 2002-01-15 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2416178A1 true CA2416178A1 (en) | 2003-07-15 |
Family
ID=27672003
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2416178 Abandoned CA2416178A1 (en) | 2002-01-15 | 2003-01-13 | Process and apparatus for the manufacture of a photographic print |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2416178A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117008426A (en) * | 2023-08-08 | 2023-11-07 | 翼存(上海)智能科技有限公司 | Image exposure method and device, electronic equipment and storage medium |
-
2003
- 2003-01-13 CA CA 2416178 patent/CA2416178A1/en not_active Abandoned
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117008426A (en) * | 2023-08-08 | 2023-11-07 | 翼存(上海)智能科技有限公司 | Image exposure method and device, electronic equipment and storage medium |
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