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Timestamp: 2015-04-18 05:14:58
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Matched Legal Cases: ['art 2', 'art 3', 'art 2', 'art 2', 'art 2', 'art 2', 'art 3']

Patent US6190308 - Endoscopic video system for correcting a video image of an object to be studied - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsAn endoscopic video system for correcting a video image of an object to be studied has a processing unit controlling an electronic image recorder which has a multiplicity of image elements, each generating an output signal upon illuminating a known test object. The processing unit has a learning mode...http://www.google.com/patents/US6190308?utm_source=gb-gplus-sharePatent US6190308 - Endoscopic video system for correcting a video image of an object to be studiedAdvanced Patent SearchPublication numberUS6190308 B1Publication typeGrantApplication numberUS 09/011,939PCT numberPCT/DE1996/001540Publication dateFeb 20, 2001Filing dateAug 19, 1996Priority dateAug 17, 1995Fee statusLapsedAlso published asEP0845187A2, WO1997007627A2, WO1997007627A3Publication number011939, 09011939, PCT/1996/1540, PCT/DE/1996/001540, PCT/DE/1996/01540, PCT/DE/96/001540, PCT/DE/96/01540, PCT/DE1996/001540, PCT/DE1996/01540, PCT/DE1996001540, PCT/DE199601540, PCT/DE96/001540, PCT/DE96/01540, PCT/DE96001540, PCT/DE9601540, US 6190308 B1, US 6190308B1, US-B1-6190308, US6190308 B1, US6190308B1InventorsKlaus Irion, Karl-Heinz Strobl, Uwe Faust, David ChateneverOriginal AssigneeKarl Storz Gmbh & Co., KgExport CitationBiBTeX, EndNote, RefManPatent Citations (9), Referenced by (13), Classifications (21), Legal Events (9) External Links: USPTO, USPTO Assignment, EspacenetEndoscopic video system for correcting a video image of an object to be studied
Hitherto fiber bundles which are �ordered� and respectively �coherent� have been employed as imaging fiber bundles in endoscopes. What is meant thereby is that the light entry surface and the light exit surface of each optical fiber of the fiber bundle is located, always in relation to the same position, on the lens plane (i.e., image plane of the endoscope lens) and the image plane (i.e., lens plane of the image recorder).
In the endoscopic video system known from DE-A-32 04 316, the imaging fiber bundle is an incoherent bundle. What is meant thereby is that the entry-side end and the exit-side end of each fiber are not disposed at the same relative position in the image plane of the endoscope lens and in the lens plane of the image recorder so that the transmitted image in the lens plane of the image recorder is �mixed up�. With regard to this, reference is made to page 7, lines 7 to 14 of DE-A-32 04 316.
A decoder, or an image processing unit, corrects the �incoherent� image signal from the image recorder in such a manner that the image is �coherently� represented, by way of illustration, on a monitor.
In the generic endoscopic video system known from DE-A-32 04 316, the relative orientation of the lens-side ends of the incoherent fiber bundles with respect to the image-side ends prior to inserting the fiber bundle into the endoscope is fixed permanently, or �once and for all�. (cf. page 8, lines 26f of DE-A-32 04 316).
Therefore, an image processing unit is provided with a �learning mode� and a �recording mode�. In the learning mode, the image of at least one known test object is recorded, which preferably is illuminated by the illumination unit. The image processing unit compares, in the learning mode, the output signal of each element of the image from the image recorder with a predetermined desired output signal from the test object. The image processing unit determines therefrom, for each image element, the change in intensity and color of the recorded image relative to that of the test object resulting from the variances in illumination due to the lens edge cut-off, transmission errors of the image transmitter, and variances in the sensitivity of the image recorder, and determines therefrom a correction value assigned to the respective image element. In the recording mode, the image processing unit corrects the respective output signal from each image element by means of the correction value assigned to that image element.
(2) Most endoscope lenses have an �edge cut-off� in the transmission function which usually is larger than the radial decrease of the transmission function which is inversely proportional to the fourth power of the distance from the optical axis (i.e., the �r4 cut-off�).
If the image errors of the �whole system� are to be corrected, the respective test chart disposed in the object field of the lens is illuminated by the light leaving the light exit aperture(s) at the distal end of the endoscope, while preferably using the illumination device and the optical cable which also are subsequently going to be utilized for recording the endoscope images.
On the other hand, if the image errors of only the �imaging system� are to be corrected, a matt glass which is homogeneously illuminated from the rear is preferably employed as the test chart.
The image processing unit calculates a two-dimensional filter matrix from the image of each test chart; for imaging a homogeneous gray or white chart, the filter matrix is basically inverse to the �endoscope white image�. Preferred is if, in order to minimize the noise caused by the recording electronics, a number of �endoscope white images� are detected and averaged for determining the inverse filter matrix.
In order to compensate for �dark spots� in the illumination, the image processing unit can amplify the signals from the individual image elements or from groups of image elements in such a manner that variances in the illumination of the object field are compensated.
In addition, the image processing unit can modify the color information of the signals from the image element, which are applied by fibers with spectral transmission properties which differ from most of the fiber bundle, by conversion of the color scale in such a manner that the color information of the image element corresponds to that of the adjacent image elements. The color compensation can be conducted by the transformation RGB (red, green, blue) in HIS, with H standing for the color value, S for color saturation and I for intensity. In this manner, by way of illustration, the occasionally occurring �yellow tinge� of fibers can be compensated.
The invented concept, that the image processing unit �learns� in the learning mode to correct the endoscope image by electronically influencing individual image elements in such a manner that the transmission errors caused by the faulty transmission properties of the whole system and, in particular of the fiber bundle, can no longer be visibly seen, permits not only correction or compensation of differences in brightness, but also other image errors. The image processing unit not only modifies the output signals from the individual image elements but also partially �re-sorts� the image elements.
The same applies to the signals from image elements which are �applied� from the spaces between the fibers. The image processing unit replaces the signals from these image elements with the image information of adjacent image elements applied by light transmitting fibers.
Usually endoscope lenses are not provided with an adjustable aperture. Exposure control or regulation, therefore, occurs by setting the lamp power of the illumination device and/or by changing the shutter speed of the image recorder. In particular, the image recorder control unit sets the different shutter speeds of the imaging recorder electronically by varying the �photon integration time� over the individual image elements.
The present invention can be utilized in a variety of different types of endoscopes. Thus, the image recorder can be disposed distally, such as by way of illustration in a kind of probe, and the image of the endoscope lens can be recorded directly or via an optical adaptation system, which, however, does not serve as the image transmitter. Of course, the image recorder can also be disposed proximally. The image recorder may be built �permanently� into the endoscope or, as is known, into a video camera which is flanged to the eyepiece of the endoscope. Particularly in this event, the embodiment of the invention which permits calibration during each examination is especially advantageous. The image transmitter, which transmits the image generated by the endoscope lens to the proximal end of the endoscope, and which is required if the image recorder is disposed proximally, may be a relay lens system which, in particular, is composed of rod lens systems and/or of elements having a non-uniform refraction index, or may take the form of an imaging fiber bundle, such as employed in flexible or thin bore rigid endoscopes.
FIG. 1 shows an endoscope 1 comprising a flexible insertion part 2 and a proximal part 3. The insertion part 2 can be steered or can be tangentially bent in a known manner by means of pulls, operating elements, etc. (not depicted). Disposed at the distal end of the insertion part 2 is an endoscope lens 4 which, without the intention of limiting the general applicability of the present invention, in the depicted preferred embodiment is a �front viewing lens� (i.e. the optical axis of the lens coincides with the longitudinal axis of the insertion part 2). Of course, within the scope of the present invention, lenses whose optical axis includes an angle with the longitudinal axis of the insertion part 2 can also be utilized. An imaging fiber bundle 5 transmits the image of lens 4 to the proximal end in such a manner that it can be observed with an eyepiece 6, which is disposed in the proximal part 3.
Corresponding image processing units are also known and can, by way of illustration, be provided with a personal computer (�PC�) of industrial standard or with a special image processor. The assignee of the present invention also provides under the brand �TwinVideo� a suitable image processing unit which carries out image rotations and reflections.
Thus, the image processing unit 19 is provided with a �learning mode� and a �recording mode�.
In both cases, a two-dimensional filter matrix is calculated, which is inverse to the �endoscope white image�. In order to minimize noise effects caused by the recording electronics 16, a multiplicity of endoscope white images are averaged.
Detection of strays due to broken fibers of bundle 5 follows homogenizing the basic brightness of the image. All black pixels are detected via an intensity threshold value criteria. All pixels lying in intensity below a certain threshold value are replaced by the �average maximum� of the active pixel within a certain search area. This process also permits recording spaces between fibers which impinge upon the individual image elements or pixels.
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DemersEndoscopic calibration method and apparatusDE102007026595A1 *Jun 8, 2007Dec 18, 2008Fraunhofer-Gesellschaft zur F�rderung der angewandten Forschung e.V.Vorrichtung und Verfahren zur Kompensation von Farbverschiebungen in faseroptischen AbbildungssystemenWO2008153969A1 *Jun 6, 2008Dec 18, 2008Storz Karl Gmbh & Co KgA video system for viewing an object on a body* Cited by examinerClassifications U.S. Classification600/109, 348/65, 348/E05.028, 600/921, 348/188International ClassificationH04N1/401, H04N7/18, A61B1/04, G02B23/26, H04N5/225, H04N5/217Cooperative ClassificationY10S600/921, G02B23/26, H04N2005/2255, H04N1/401, H04N5/2254, A61B1/042European ClassificationG02B23/26, A61B1/04D, H04N5/225C4, H04N1/401Legal EventsDateCodeEventDescriptionApr 9, 2013FPExpired due to failure to pay maintenance feeEffective date: 20130220Feb 20, 2013LAPSLapse for failure to pay maintenance feesOct 1, 2012REMIMaintenance fee reminder mailedJul 24, 2008FPAYFee paymentYear of fee payment: 8Jul 29, 2004FPAYFee paymentYear of fee payment: 4Jan 10, 2003ASAssignmentOwner name: KARL STORZ GMBH & CO. 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