WO2004105396A1 - Method for identifying bad pixel against a non-uniform landscape - Google Patents
Method for identifying bad pixel against a non-uniform landscape Download PDFInfo
- Publication number
- WO2004105396A1 WO2004105396A1 PCT/IL2004/000401 IL2004000401W WO2004105396A1 WO 2004105396 A1 WO2004105396 A1 WO 2004105396A1 IL 2004000401 W IL2004000401 W IL 2004000401W WO 2004105396 A1 WO2004105396 A1 WO 2004105396A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- matrix
- landscape
- sensor
- matrix sensor
- combined image
- Prior art date
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F41—WEAPONS
- F41G—WEAPON SIGHTS; AIMING
- F41G7/00—Direction control systems for self-propelled missiles
- F41G7/001—Devices or systems for testing or checking
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S3/00—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
- G01S3/78—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using electromagnetic waves other than radio waves
- G01S3/782—Systems for determining direction or deviation from predetermined direction
- G01S3/783—Systems for determining direction or deviation from predetermined direction using amplitude comparison of signals derived from static detectors or detector systems
- G01S3/784—Systems for determining direction or deviation from predetermined direction using amplitude comparison of signals derived from static detectors or detector systems using a mosaic of detectors
Definitions
- the present invention relates to matrix detectors, and in particular to the real-time identification of bad pixels in such detectors against a non-uniform landscape.
- Optical systems based on matrix image sensors or "matrix detectors” are known. Also known are methods of identifying bad or damaged pixels in these matrices.
- the identifications normally include a factory two-point non-uniformity correction (TPC-NUC).
- TPC-NUC factory two-point non-uniformity correction
- the two-point NUC refers to a test in which a uniform black body image is presented to the detector at two different temperatures. The detector output is measured, and from these measurements one obtains three figures of merit for each picture element (pixel). These three figures of merit are gain (responsivity), level (dark current), and noise. The values of gain, level, and noise should be roughly the same for all the pixels.
- a pixel that deviates significantly from the others in any of these three figures of merit is considered (tagged) defective (bad) and included in a "bad pixel” table.
- This initial tagging of bad or damaged pixels does not assure long-term stable performance of the detector.
- the matrix may experience during its lifetime deterioration of additional pixels, which need then to be added to the bad pixel table.
- the original bad pixel table is unstable in time.
- the fact that the deviation is constant reflects disadvantageously on the system performance.
- Detecting such bad pixels includes the steps of a) positioning a uniform black body in front of a static detector, and sampling of a large number of images; b) obtaining gain level and noise figures for each pixel, c) identifying bad pixels that deviate from a mean value by more that a given criterion; and d) adding the identified damaged pixels to the "bad pixel" table.
- the main problem and disadvantage of this method lies in the need for a uniform black body. Such a body is normally not available under field conditions, and certainly not available during normal operation of the system, for example when the detector is in flight, attached to a body such as a missile. There is thus a widely recognized need for, and it would be highly advantageous to have, an on-line, real-time, simple, and fast method for identification of bad pixels that appear after the original bad pixel table is formulated.
- the present invention describes a method for on-line, real-time, simple and fast identification of bad pixels that appear after an original bad pixel table is formulated.
- a method for identifying defective pixels in a matrix imaging sensor comprising the steps of moving the matrix sensor in a prescribed motion with respect to a background landscape, acquiring a combined image of the landscape, and identifying bad pixels in the matrix sensor from the combined image, whereby the identification is performed on-line in real-time without necessitating the use of a black body.
- the step of moving includes rotating the matrix sensor.
- the step of moving includes translating the matrix sensor in a smooth motion along a circle.
- the matrix sensor resides in a missile homing head.
- the matrix sensor is fixedly attached to the missile homing head, and the step of moving the matrix sensor includes moving the missile homing head.
- the step of identifying bad pixels includes applying a finite impulse response filter on the combined image.
- the filtering is performed with a High Pass filter.
- a system for identifying a bad pixels in a matrix imaging sensor comprising moving means to move the matrix detector in a prescribed motion that enables the acquisition of a combined landscape image, and image processing means to identify bad pixels in the matrix sensor using the combined image.
- the matrix sensor is located inside a missile homing head, and wherein the moving means include means to rotate the matrix sensor relative to the homing head.
- the matrix sensor is fixedly connected to a missile homing head, and wherein the moving means include means to rotate the homing head.
- the image processing means include a finite impulse response filter for filtering the combined image.
- the impulse response filter is a high pass filter.
- FIG. 1 shows the principle of the method of the present invention
- FIG. 2 shows in (a) a single image of a landscape, and in (b) a combined image that results from the averaging of many rotated landscapes (a);
- FIG. 3 shows a filtered combined image with clearly delineated bad pixels;
- FIG. 4 shows a schematic block diagram of a preferred embodiment system used to implement the method of the present invention
- the present invention is of a method for on-line, real time, simple and fast identification of bad pixels that appear after an original bad pixel table is formulated.
- the principles and operation of the method according to the present invention may be better understood with reference to the drawings and the accompanying description.
- FIG. 1 shows the principle of the method.
- the matrix detector (not shown) viewing a background landscape (or simply "background") 10 is moved in a prescribed motion around a center axis 12.
- the prescribed motion may be rotation, translation along a circle, etc.
- the motion is simple rotation. If the detector rotation is rapid relative to changes in the landscape, axis 12 points approximately to the same feature in the landscape.
- the detector is typically located in the homing head, and rotating the detector is equivalent to rotating the missile head (see system description below).
- Missile homing heads always have a built-in mechanism for moving the head in any prescribed motion within some range (called field of regard), and which can therefore perform the mentioned rotation.
- the homing head may also move in other types of motions, such as a translational motion along a circle.
- the necessary conditions for the motion are that it is smooth and continuous, i.e. no jerky motion or stopping are allowed. It should be clear to anyone knowledgeable in the art that any type of motion that fulfils these conditions and renders the required results is considered within the scope of the invention.
- the generic term of "rotation" will be henceforth used to mean all these types of motion.
- Each pixel 16 of the matrix rotates around axis 12 on a radius R, covering over a full cycle a "ring" of landscape given by 2 ⁇ RdR.
- This slowly moving landscape is sampled in a large number of cycles, providing a large number of images that are then overlaid (superposed) to one combined image.
- the detector rotation is fast relative to the movement of the landscape, the set of images forming the combined image is essentially of the same landscape.
- the point in the combined image seen by the center matrix element of the detector relates approximately the same feature in all images of the set. The method works even if the center point is not the same feature in each landscape image.
- each pixel represents the average value of that matrix element over the ring.
- FIG. 2a shows a single image of a landscape 50
- FIG. 2b shows a combined image 52, which results from the averaging of many rotated landscapes 50.
- the combined image appears as a series of concentric rings 54 a, b, c, ... of various gray shades, where the variation in intensity of all pixels in a single ring is no larger than the basic pixel-to-pixel variation.
- rotating the scene averages out the impact of individual landscape bright spots, achieving in effect a uniform background, or at least a background uniform along concentric rings, and varying slowly in the radial direction, as clearly seen in the pictures.
- the typical number of images required by the method is on the order of 100; however, this number depends on performance: the more images one uses, the smoother the averaged image comes out, resulting in a smaller probability of misidentifying a bad pixel.
- increasing the number of images increases the time required to complete the procedure, which is a dead-time as far as normal use of the system is concerned.
- the rotation speed should preferably be such that the system would undergo several complete rotations during this time.
- the numerical filter used may be different from the one specified above (with coefficients -1, +2, -1 along a row or column).
- this filter is preferably a High Pass filter in order to accentuate the deviation of the different pixel from its neighbors, while not being affected from slow variations perpendicular to the rings. It is well known that High Pass filters may be realized in many ways, as pointed out in standard engineering textbooks, and all the various ways of implementing them are considered within the scope of the present invention.
- the data acquisition and processing mentioned above are preferably done with these already existing means.
- a homing seeker head 100 comprises a matrix detector 102 that has a plurality of pixels, potentially among them one or more bad pixels as defined above.
- Matrix detector 102 rotated by rotating means 104, rotates around an axis 106, while looking at a landscape 108.
- the rotation of the detector is fast relative to changes in the landscape. For example, if the detector resides in a missile homing head, and the missile is fixedly attached to a maneuvering aircraft, the turns and rolls of the aircraft cause the missile length axis to point at a changing landscape. However, if the detector rotation is much faster than the relative movement of the aircraft vs the landscape (e.g. the landscape is far, and the detector acquisition time for the combined image is very short) the detector looks essentially at the same landscape during the image acquisition.
- detector 102 may be fixedly attached to homing head 100, in which case the rotating means rotates the homing head itself, as explained above.
- detector 102 may be flexibly attached to the homing head, driven independently of the homing head by means 104.
- Homing head 100 further comprises image processing means 112, which typically include a microprocessor 114, a storage means 116, and filtering means 118, preferably a High Pass filter.
- image processing means 112 typically include a microprocessor 114, a storage means 116, and filtering means 118, preferably a High Pass filter.
- the information acquired by detector 102 is transferred to image processing means 112 by a fixed electrical harness 120 and trough a slip ring assembly 122 (that allows a rotational movement between both parts).
- the information may be transferred wirelessly from a transmitter attached to detector 102 to a receiver attached to means 112.
- Microprocessor 114, storage means 116 and filtering means 118 cooperatively process the information by well-known image processing techniques.
- the present invention provides an on-line, real-time, simple and fast method for identification of bad pixels that appear after the original bad pixel table is formulated.
- the method of the present invention does not require a uniform black body, and is therefore particularly advantageous and useful in field conditions, e.g. for missiles in flight.
Abstract
Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP04732406A EP1627531A4 (en) | 2003-05-26 | 2004-05-12 | Method for identifying bad pixel against a non-uniform landscape |
US10/557,805 US7471311B2 (en) | 2003-05-26 | 2004-05-12 | Method for identifying bad pixel against a non-uniform landscape |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
IL156124A IL156124A (en) | 2003-05-26 | 2003-05-26 | Method for identifying bad pixels against a non-uniform landscape |
IL156124 | 2003-05-26 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2004105396A1 true WO2004105396A1 (en) | 2004-12-02 |
Family
ID=32587587
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/IL2004/000401 WO2004105396A1 (en) | 2003-05-26 | 2004-05-12 | Method for identifying bad pixel against a non-uniform landscape |
Country Status (4)
Country | Link |
---|---|
US (1) | US7471311B2 (en) |
EP (1) | EP1627531A4 (en) |
IL (1) | IL156124A (en) |
WO (1) | WO2004105396A1 (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7710472B2 (en) * | 2006-05-01 | 2010-05-04 | Warner Bros. Entertainment Inc. | Detection and/or correction of suppressed signal defects in moving images |
RU2012145349A (en) * | 2012-10-24 | 2014-05-10 | ЭлЭсАй Корпорейшн | METHOD AND DEVICE FOR PROCESSING IMAGES FOR REMOVING DEPTH ARTIFacts |
WO2019194106A1 (en) * | 2018-04-06 | 2019-10-10 | オリンパス株式会社 | Image processing device, image processing method, and image processing program |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6411329B1 (en) * | 1997-08-22 | 2002-06-25 | Omega Electronics S.A. | System, in particular for timing races; including a photosensitive sensor and method for adjusting the alignment of such a system with a line across which objects or persons pass |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5336894A (en) * | 1992-04-21 | 1994-08-09 | The United States Of America As Represented By The Secretary Of The Air Force | Universal infrared heat source controller |
DE4338390C2 (en) * | 1993-11-10 | 2001-06-13 | Bodenseewerk Geraetetech | Scene simulator, especially for testing infrared sensors in homing heads |
US5460529A (en) * | 1994-06-15 | 1995-10-24 | The United States Of America As Represented By The Secretary Of The Army | Target simulator device and technique |
AU2123297A (en) * | 1996-02-12 | 1997-08-28 | Golf Age Technologies | Golf driving range distancing apparatus and methods |
IL118784A (en) * | 1996-07-03 | 1999-04-11 | Eliav Medical Imaging Systems | Method and apparatus for processing images for removal of artifacts |
US7142705B2 (en) * | 2001-05-01 | 2006-11-28 | Canon Kabushiki Kaisha | Radiation image processing apparatus, image processing system, radiation image processing method, storage medium, and program |
US6928194B2 (en) * | 2002-09-19 | 2005-08-09 | M7 Visual Intelligence, Lp | System for mosaicing digital ortho-images |
-
2003
- 2003-05-26 IL IL156124A patent/IL156124A/en not_active IP Right Cessation
-
2004
- 2004-05-12 EP EP04732406A patent/EP1627531A4/en not_active Withdrawn
- 2004-05-12 US US10/557,805 patent/US7471311B2/en not_active Expired - Fee Related
- 2004-05-12 WO PCT/IL2004/000401 patent/WO2004105396A1/en active Application Filing
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6411329B1 (en) * | 1997-08-22 | 2002-06-25 | Omega Electronics S.A. | System, in particular for timing races; including a photosensitive sensor and method for adjusting the alignment of such a system with a line across which objects or persons pass |
Also Published As
Publication number | Publication date |
---|---|
EP1627531A4 (en) | 2007-08-22 |
US7471311B2 (en) | 2008-12-30 |
US20060215046A1 (en) | 2006-09-28 |
EP1627531A1 (en) | 2006-02-22 |
IL156124A0 (en) | 2003-12-23 |
IL156124A (en) | 2010-04-15 |
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