WO2013178213A2 - Procédé de correction automatique de reproduction d'un projecteur - Google Patents

Procédé de correction automatique de reproduction d'un projecteur Download PDF

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Publication number
WO2013178213A2
WO2013178213A2 PCT/DE2013/000291 DE2013000291W WO2013178213A2 WO 2013178213 A2 WO2013178213 A2 WO 2013178213A2 DE 2013000291 W DE2013000291 W DE 2013000291W WO 2013178213 A2 WO2013178213 A2 WO 2013178213A2
Authority
WO
WIPO (PCT)
Prior art keywords
image
projected
projector
under normal
normal conditions
Prior art date
Application number
PCT/DE2013/000291
Other languages
German (de)
English (en)
Other versions
WO2013178213A3 (fr
Inventor
Heiko CORNELIUS
Original Assignee
Cornelius Heiko
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Cornelius Heiko filed Critical Cornelius Heiko
Publication of WO2013178213A2 publication Critical patent/WO2013178213A2/fr
Publication of WO2013178213A3 publication Critical patent/WO2013178213A3/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3179—Video signal processing therefor
    • H04N9/3185—Geometric adjustment, e.g. keystone or convergence
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/12—Picture reproducers
    • H04N9/31—Projection devices for colour picture display, e.g. using electronic spatial light modulators [ESLM]
    • H04N9/3191—Testing thereof
    • H04N9/3194—Testing thereof including sensor feedback

Definitions

  • the invention relates to a method for automatic imaging correction of a projector for digitized images, wherein the projector has a camera for recording the projected image and wherein the recorded projected image is compared with at least one image projected under normal conditions and depending on the comparison the projection optics of the projector are changed and / or the projected image in the projector is distorted until the recorded, projected image is identical to the at least one image taken under normal conditions in the range of a preselected tolerance interval and a corresponding projector for the projection of digitized Images to a projection screen.
  • Projectors for the projection of digitized images on any projection surface receive via a dedicated interface a signal of a digitized image and project the image on the projection surface via a corresponding projection optics. It is necessary that the geometry of the projection surface and the projection optics are matched to each other in order to obtain a sharp and distortion-free image. In addition to the coordination of the distance of projection optics and screen is also to take into account that the projector often has to be positioned in relation to the projection surface so that a central projection is not possible.
  • the projector projects from the direction of the projector on an oblique screen or the other way round, the projector is not centered and perpendicular in relation to the screen.
  • the placement problem goes hand in hand with the need for an image correction.
  • Typical aberrations if the projection optics are not set correctly, are the chromatic aberration that causes a slightly different image for different colors. This error is due to the dispersion of the glass used and not optimally adjusted projection optics makes this error noticeable.
  • Another mistake is the so-called distortion, in which a picture in the form of a horizontally lying quadrilateral is distorted to a bulbous, bulging ton or - inversely thereto - to a pillow with extended corners.
  • the two-dimensional image to be projected appears to be three-dimensionally collapsed or expanded for a viewer.
  • the slanted arrangement of the image plane of the projector and the projection plane creates trapeze effects in which a projected quadrilateral is distorted to a trapezoid when projected onto the projection plane.
  • the projected image experiences a corresponding distortion.
  • the object of the invention is therefore to automate the imaging correction.
  • the invention is solved by the method according to claims 1 to 5 and by the projector according to claims 6 to 10.
  • the invention it is proposed to equip the projector with a camera which records the projected image and to use a control device which internally compares the taken, projected image with an image taken under normal conditions and the projection optics for so long Depending on the comparison within the projector, the digital image itself is distorted and / or distorted until the recorded, projected image is identical to an image that was taken under normal conditions, whereby a predetermined degree of tolerance is accepted.
  • the RMS error of individual selected pixels is determined. If the RMS error of the measured deviation as a tolerance value is less than 5% of the image diagonal, preferably less than 1% of the image diagonal, then the images are considered identical and the control loop comes to a standstill. [07]
  • the RMS error in English "root-mean-square” or German the “quadratic mean” is determined by the mathematical calculation of the root mean square of all the distances from the nominal position of each selected pixel to the measured position of this pixel , where each individually determined distance is included as a fraction of the image diagonal in the calculation.
  • the projector inserts a test image into the desired image to be projected only briefly, the time duration preferably being less than 1 / 18 s lasts. This time is just no longer perceived by the human eye when the test image is temporally bound by two identical images, ie when an identical or nearly identical image is displayed before and after the test image. Depending on the type of image to be projected, however, another time period is advantageous. For moving digitized images, it is suitable to display a test image within two individual images, which are shown in typical frequency, ie 1/24 s.
  • a time of less than 1/25 s or 1/50 s is suitable. Times of less than 1/30 s or 1/60 s are suitable for US standard images.
  • the image correction in this case is carried out exclusively by these briefly recorded, projected test images [09]
  • the test image is designed so that image analysis algorithms can easily and quickly identify selected points, whether the captured, projected image is distorted or not.
  • This recorded, projected test image is then compared with a same test image, which has been recorded under normal conditions, ie ideal projection conditions with optimally adjusted projection optics, and a control algorithm determined on the basis of the comparison result, the control strategy according to predetermined rules to equalize the projected image.
  • the ideal control strategy is to correct a detected chromatic aberration by varying the corresponding lens distances or lens positions within the projection optics. Also, such distortion errors as pillow errors can be compensated. Keystone errors are corrected by varying the position of the image plane within the projector. Additional distortions that are irregular, for example due to a curved or off-screen projection surface, are achieved by digital inverse distortion of the image. It has proven to be advantageous if the projector in each image dimension at least one higher resolution by a factor of 2 than the image to be projected. At the time of this application, although high-resolution projectors are known with an image score of well over 2,000 in the horizontal and well over 1,000 in the vertical. Nevertheless, image resolutions for moving pictures and also for simple presentations on the order of 640 x 480 pixels are still quite common. The high-resolution projector would thus be able to equalize a distorted image due to the higher resolution.
  • FIG. 1 Sketching of a barrel-shaped distortion
  • FIG. 2 Sketching of a cushion-shaped distortion
  • FIG. 3 Sketching of a keystone error
  • FIG. 4 a sketch of a chromatic aberration
  • FIG. 6 a sketch of an alternative test pattern
  • FIG. 8 shows a projector according to the invention.
  • FIG. 1 shows the result of a distortion due to a barrel-shaped distortion.
  • a rectangle 1 to be projected which assumes the dashed form when ideally projected, is distorted by an improper adjustment of the projection optics to a barrel-shaped rectangle 2 according to the solid line, the sketch chosen here exaggerating the error for better visualization.
  • Projection optics are like a telephoto lens to it able to independently vary the aperture angle and sharpness. If the opening angle is too large or too small, this distortion effect is produced so that the barrel-shaped distortion effect can be corrected by varying the opening angle.
  • the lenses within the projection optics gradually align, the curved lines of the barrel-shaped rectangle move inward according to the arrows drawn, leaving the imaged corners of the ideally projected and barrel-shaped rectangles contiguous.
  • FIG. 2 shows the aberration that is inverse to the aberration in FIG. 1, the pincushion distortion. This could be understood as an over-correction of barrel distortion or vice versa.
  • an ideally projected rectangle 1 is distorted into a rectangle 3 which is in the form of a pillow. Even with this distortion error exaggerated here, the pincushion distortion effect is corrected by a variation of the opening angle.
  • the curved lines of the barrel-shaped rectangle shift outward according to the arrows drawn, with the imaged corners of the ideally projected and the square pillow-shaped rectangles remain on each other.
  • the aperture angle, the sharpness and the magnification of the digital image must be set simultaneously so that the change in the aperture angle does not change the image size, so that then the vertices of the two drawn figures, ideally projected rectangle 1 and rectangular shaped cushions 3 remain virtually unchanged.
  • the trapezoidal distortion is an aberration due to a relative skew of the image plane and the projection plane.
  • This keystone error is outlined in FIG. In this case, a rectangle 1 projected with an ideal projection is distorted to a rectangle 4 trapezoidal. Due to the misalignment of the image plane and the projection plane, the central projection enlarges a point further away from the projection optics or displays it further from the center of the projection. This projection error can be compensated by an inclination of the image plane within the projector, in the ideal state, the image plane is aligned parallel to the projection plane.
  • FIG. 4 shows a sketch of the error of a chromatic aberration.
  • the three trapezoids 5, 6 and 7 melt into a rainbow spectrum. If, on the other hand, different monochromatic light sources, such as lasers, are used as the projection light, then the three colors of the trapezoids 5, 6 and 7 separate into different trapezoids.
  • this error can also be corrected to a predetermined extent by a relative shift of different lens groups within the projection optics.
  • An ideal projection optics does not show these errors, but due to the unavoidable dispersion, the different refractive indices of the lens lenses, this error is almost permanent, but - depending on the type of lens - still within certain limits adjustable.
  • FIG. 5a, FIG. 5b and FIG. 5c show a masking of an imaged projection error, by means of which the automatic method for automatic imaging correction is explained.
  • a barrel-shaped distortion distorts the tonally distorted rectangle 2, shown in lines.
  • a camera immediately adjacent to the projector preferably with very small lens dimensions, records the projected image of the projector. The fact that the camera has very small dimensions compared to the projection optics, the focus on "infinite" can provide sharp images even at 2m distance to a distant projection screen.
  • This camera delivers the image of the barrel-shaped distorted rectangle, whereby the rectangle is masked as a simple test image within a computing unit, within the camera or already during the projection.
  • a cross-shaped mask 10 which is placed over the recorded image of the barrel-shaped distorted rectangle 2 according to Figure 5b, the image is formed in accordance with the solid line in Figure 5c.
  • the positions of the four sections of the barrel-shaped distorted rectangle 2 are compared within the control device by a computing unit with a stored image of an ideally projected rectangle, according to the dotted lines remaining after masking.
  • An image recognition algorithm can quickly capture these very few image contents, determine the focus of the identified image content, and determine the distance to the ideal center of gravity that lies within the area of the dotted lines.
  • This mask results in distance vectors distance vector 20, distance vector 21, distance vector 22 and distance vector 23, which each have a direction and a length, for example as a fraction of a picture diagonal.
  • the ideal control strategy for correcting barrel distortion, pincushion distortion and trapezoidal distortion can be read.
  • this table has at least 3 states for each vector, namely "up”, “down”, "right” for the two top and bottom image contents and "right", "left” and "right” for the two at the Pages lying image content.
  • a completely different type of control strategy is known, for example, in the image equalization for the reading of two-dimensional matrix codes.
  • an easily recognizable pattern 8 which is identified by an image recognition algorithm, is inserted into the corners of a rectangle.
  • FIG. 8 shows a projector 100 according to the invention which has projection optics 101, a camera 102 for recording the projected image, and also a control unit 103 as a computing unit which is capable of analyzing image contents and accordingly the projection optics set to motorized.
  • the control device can adjust the image plane and also adjust individual lens groups to each other in order to achieve an ideal image during projection by the variation of the image plane and lens distances.
  • the exact control strategy depends on the selected projection optics, which can have a large number of setting parameters depending on the design.
  • the control strategy is then dependent on a lens model implemented in the control device.
  • control device may also have an image processor that changes the digital signal of an image to be projected so that individual Pixels or individual pixel groups within the image shifted, one-dimensional or two-dimensional compressed or expanded, possibly even distorted.
  • a special type of image correction is the correction of detected brightness gradients and color gradients.
  • the brightness can be adjusted averaged. This type of correction can be adjusted using the average measured brightness of the captured projected image.
  • brightness differences When projecting onto projection surfaces inclined relative to the projector, brightness differences inevitably arise, which can be corrected by reversing the brightness distribution of the individual image contents.
  • the color gradient of a uniform white image can be corrected by a corresponding color mask.
  • Shading can not be corrected by adjusting the projector parameters.
  • a detected shading can be used as a control signal to give, for example, the migration of shading as a signal to the projector or to the projecting computer in the manner of a computer mouse signal.

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Geometry (AREA)
  • Transforming Electric Information Into Light Information (AREA)
  • Projection Apparatus (AREA)

Abstract

L'invention concerne un procédé de correction automatique de reproduction d'un projecteur (100) pour des images numérisées, ledit projecteur (100) présentant une caméra (102) pour enregistrer l'image projetée et l'image projetée enregistrée étant comparée à au moins une image projetée dans des conditions normales et en fonction de la comparaison l'optique de projection (101) du projeteur (100), ladite image projetée enregistrée est modifiée et/ou l'image projetée est déformée dans le projecteur (100) tant que l'image projetée enregistrée demeure identique à la au moins une image enregistrée dans des conditions normales, dans la plage d'un intervalle de tolérance présélectionné. Le procédé selon l'invention et le projecteur correspondant permettent d'effectuer une correction automatique de reproduction.
PCT/DE2013/000291 2012-06-01 2013-05-28 Procédé de correction automatique de reproduction d'un projecteur WO2013178213A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102012010814A DE102012010814A1 (de) 2012-06-01 2012-06-01 Verfahren zur automatischen Abbildungskorrektur eines Projektors
DE102012010814.1 2012-06-01

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WO2013178213A2 true WO2013178213A2 (fr) 2013-12-05
WO2013178213A3 WO2013178213A3 (fr) 2014-01-23

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WO (1) WO2013178213A2 (fr)

Cited By (3)

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CN108769636A (zh) * 2018-03-30 2018-11-06 京东方科技集团股份有限公司 投影方法及装置、电子设备
CN112449165A (zh) * 2020-11-10 2021-03-05 维沃移动通信有限公司 投影方法、装置及电子设备
CN115514943A (zh) * 2022-08-19 2022-12-23 陈冠南 一种自由曲面镜片成像质量的检测方法

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102013009803A1 (de) 2013-06-12 2014-12-18 Heiko Cornelius Verfahren zur automatischen Abbildungskorrektur eines Projektors

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FR2660090B1 (fr) * 1990-03-23 1994-07-29 Thomson Csf Dispositif de visualisation par projection a boucle de contre-reaction pour la correction de l'ensemble des defauts de l'image projetee.
DE10022009C2 (de) * 1999-11-26 2002-12-05 Inb Vision Ag Verfahren und Einrichtung zur Bestimmung und mindestens teilweisen Korrektur der Fehler eines Bildwiedergabesystems
US7227592B2 (en) * 2003-09-26 2007-06-05 Mitsubishi Electric Research Laboratories, Inc. Self-correcting rear projection television
US7262816B2 (en) * 2004-10-22 2007-08-28 Fakespace Labs, Inc. Rear projection imaging system with image warping distortion correction system and associated method
US8406562B2 (en) * 2006-08-11 2013-03-26 Geo Semiconductor Inc. System and method for automated calibration and correction of display geometry and color
WO2008155771A2 (fr) * 2007-06-21 2008-12-24 Maradin Technologies Ltd. Système de projection d'image avec rétroaction

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108769636A (zh) * 2018-03-30 2018-11-06 京东方科技集团股份有限公司 投影方法及装置、电子设备
CN112449165A (zh) * 2020-11-10 2021-03-05 维沃移动通信有限公司 投影方法、装置及电子设备
CN112449165B (zh) * 2020-11-10 2023-03-31 维沃移动通信有限公司 投影方法、装置及电子设备
CN115514943A (zh) * 2022-08-19 2022-12-23 陈冠南 一种自由曲面镜片成像质量的检测方法
CN115514943B (zh) * 2022-08-19 2024-04-23 陈冠南 一种自由曲面镜片成像质量的检测方法

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WO2013178213A3 (fr) 2014-01-23
DE102012010814A1 (de) 2013-12-05

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