Multispectral Imaging

Multispectral imagination is utilize oven an extremely wide spectral domain. It started with NASA using the proficiency for satellite imaging using kilometer-length radio waves, to the technique macrocosm exampled by rhetorical science using light in the visible to the near infrargond frequency region, to medical examination rhetoricals using MeV gamma rays (National Research Council 1998) The use of Multispectral imaging in forensics and law enforcement for the examination of a wide variety of evidences is a flying line that is growing but has non yet r from each o get hold of the state of being a univers tout ensembley pass judgment practice.The technique is being utilise for analyzing photographic and word picture based evidence, and likewise for DNA synopsis in recent clock (Lanir 2005) Using Multispectral imaging has twain advantages as well as indisput satisfactory disadvantages in the abridgment of a video. In addition, there atomic number 18 most pre -requisites take oned which make the approach limit to certain situations. All these points are discussed subsequently in this section. Advantages of Multispectral Imaging technique 1.Advantage over naked-eye viewing magic spell a humane eye has the capability of divers(prenominal)iating between millions of colourations and mingled combinations it is obvious that the perception is usually dependant on a medley of different wavelength. In other words, the distinguish spectral information as received by eyes is belt up incomplete. The reason for this is because the visible specify of light, no matter the degree of its complexity, is still divided into the three introductory colors red, green and blue. Multispectral imaging arouse generate the accurate and complete optical spectra at e really pixel.Finally and foresee serve uping estimator software can be used for getting the maximum information from each of the pixels (Condea , Haneishia, Yamaguchia , Ohyama & Baa z J 2007) This might non be very important and might come along like overkill for regular vision. But in parapraxis of forensics, where the actual and meticulous consumeive information is necessary, this capability becomes very helpful as the data is alone analyzed. Differences in spectra can be used for the accurate undercover work of inappropriate particles in a terrain or differences in finger prints from different individuals .Advantage over cameras Forensic science is the capture and preservation of accurate consider. Conventional color films and digital color cameras likewise break the various colors combinations in RGB, so the information is just as inaccurate as seen with a naked eye. Hence, multispectral imaging scores over using these equipments to a fault (Chieu 2001) In addition, multispectral imaging can be used in areas which are unaccessible ad can give simple multi-temporal readings. The area range of the exposure is also more than than what is for a d igital camera.Also, until very recently the use of numerical processing was fairly restricted in the camera ashess. Finally, Multispectral imaging also offers light attenuation techniques (Westland & Ripamonti 2004) 3. Avoid Contamination of the shame facet One of the advantages leave aloned by using multispctral imaging is that there is no need for constant physical tactile sensation with the nuisance scene. This characteristic helps in twain types of investigations. In human face of analyzing a crime scene for evidence, the constant contact inwardness contamination which can be avoided because the multispectral imaging can be taken aerially.This feature is also used in the forensic analysis of ancient enrolments where the contact with the document should be minimal. In such cases the document can be reconstructed with minimum contact. The aerial interpret fetching capability also helps in dangerous locations also, as in the case of visiting the location of a minefiel d. The initial identification of a minefield helps in localizing the area using an airborne multi-band camera. Using light in both the visible and infrared region minefield having both surface mines and well as buried mines can be detected (Sjokvist Lundberg Gu & Ulvko n. . )4. Time and court Saving Using multispectral imaging the complete analysis can be done faster than using conventional methods and also cost for producing the alike(p) results using the other spectroscopic methods is a separate costlier. This is because, the wide range of performance of multispectral technique i. e. from ultraviolet to visible to thermal infra red, room that m more or less(prenominal) an(prenominal) different physical parameters can be analyzed simultaneously. Also the data has no major spatial co-registration businesss.As an example in case of medical diagnostics and forensics, the interface used for multispectral imaging is easy to use and also much cheaper than conventional systems l ike the 7T MR scanner. Disadvantages of Multispectral Imaging technique Multispectral imaging in non without its faults. Some of them are primarily due to he figure and requirement of the individual area where multispectral imaging is used. 1. Complete Image not provided Multispectral imaging does not provide complete 3D paradigm. The reason is that this technique does not offer both method to separate the effect of acculturation from scatterSpatial dissolving agent Multispectral imaging due to its optical nature does not provide for complete spatial resolution. Some ways that have been suggested is to examine by contrasting with IR image but with acoustic resolution. In the case of detection of landmines, the trouble is that while the technique can judge the heading or absence of mine over an area, the exact location cannot be pinpointed. This means that the technique can be just used to find if the area is contaminated by mines, but the detected rate of each single mine i s not high (Sjokvist Lundberg Gu & Ulvko n. d. )System Complexity epitome of complex systems poses a problem when multispectral imaging is used. This tendency increases as the system complexity increases. For example , in case of mine detection, the mine field is assumed to have a near perfect alignment which is not always possible in case of real time environments (Sjokvist Lundberg Gu & Ulvko n. d. ) 2. Noise Vulnerability This is one of the critical requirements of any forensic detection techniques. Multispectral image by its very nature are sensitive to any pollutants, which is why the crime scene has to be assumed to be cracking from any external influences.The spectral features of any foreign body is more important that its chemical or biological properties, which raises the probability of mistakes as all environmental substances have broad spectral absorbance bands (Miskelly & Wagner 2005) 3. Complexity of analysis A crime scene can be considered to have a limited number of objects having distinct spectral characteristics. Some experts feels that most of the individual scene should hence be individually analyzed for a accurate reproduction.This means that each scene would have different multispectral properties which would mean a different system, making the detection complex. In addition, this also calls for advanced digital planetary house processing techniques and the possibility of large quantities of data to be analyzed (Gordon 2001) 4. use in Crime Scene While multispectral imaging is increasingly being used to analyze physical evidence, the first hand usage in crime scenes is not very popular even directly. This is because the technique is much too costly for usage for normal forensic departments.In addition, the equipments are not portable enough for it to be easily taken to a crime scene (Gordon 2001) 5. Image recreation This problem occurs at the time of image recreation. However, not every field faces this problem. In case of docume nt forensics, where the concluding document has to be reconstructed, specialists observe the complete image onwards decision making on the parts to include. The image recreation needs human battlefront however. However, in case of some other forensic scene recreation, the problem might become more difficult.This is because, the image given by a multispectral analysis is 3D in nature, though not complete. But the image presented or used by an observer is 2D. Hence, the transformation of the image and the components to select the exact transformation is not very easy (MacDonald & Luo 2002) Limitations of Multispectral Imaging Technique Multispectral image techniques need some additional technology boost before they can be successfully used for forensic applications universally. 1. Problems in analyzing elaborate As has been said earlier, multispectral imaging was used by satellites for recording data.From this distance, any blurring is attributed to distance and smaller enlarge were usually not expected. When the technique was use for analyzing objects at smaller distances, like forensic analysis of document, initially the results were satisfactory. This means that the results obtained were much better than was observed using the optical techniques employing the RGB technique. However, the problem arose when the details in the document were not very clear. (Hill 2005). The image size is also not that of the original image which also makes the alignment difficult.Also the many imperfections which are inherent of the real world, makes it difficult for the technique to be used in the real-time situation. Here, the contamination is almost entirely expected. The noise is however not acceptable while using the multispectral imaging technique. Researches are on for determination a suitable fusion technique which is both adaptive and ingenious enough to take care of these conditions, though it might take some time for this to actually materialize (Danien & Gran t 2006) 2.Calibration Errors There is another problem that might happen when multispectral imaging is used for analyzing details at subatomic levels. The problem is related to precision of the technique and occurs due to imperfect normalisation of equipments. The shifts means false data being sued as input which raises the error when the output data is analyzed. This in turn effects the spatial resolution when a simple approximation is needed for the temporal evolution. There is also a very high requirement for symmetry as the technique is primarily related to pixel information (Koch Haan & Mancini 2004) . Need for reconstruction software An imaging software package is essential for making the final image which would be analyzed.The problems lie when this imaging software is not up to the standard. In this case, the entire advantages are in the danger of being lost. Unfortunately, the reconstruction still requires human presence despite the sophisticated software packages availa ble. The output image deciphering from these software have proved to vbe confusing, and hence scientists prefer analyzing in the human presence wheich is a tedious process (Foy & Theiler n. d)Future Application and Trends in Multispectral imaging With the many advantages that can be achieved using Multispectral imaging techniques, the near rising will see more research in this field. Forensics will now be the main focus, as because of the accuracy of data that can be found using this technique. There are however many issues that need immediate attention. The most important is the image retrieval software which is very important for the analysis of the evidence by investigators. The area is seeing lot many advances with many tools being developed that target specific areas of forensic work.The second target area is the reduction in equipment size and complexity. character in satellites did not put a lot of restrictions to the size of the equipment. However, when it is used by inves tigators for crime scene detection, the size of equipment becomes important. The equipment should also be able to access spaces, meaning that it should be able to cover the entire crime scene. The interest in making smaller electronic devices with higher computer power may prove to be very helpful in this case. In addition, the research is also being done to improve the tincture of optical systemsFinally, the multispectral imaging technique itself should be improvised such that its aptitude to noise is reduced. In many cases like landmine detection, a prior analysis of the land is first doe before using the multispectral equipment, which is a skillful solution Investigators are finding that using multispectral imaging assists in the process of analyzing evidence. Sufficient research in this field to make the technology more efficient, will help it in becoming a universally accepted technology.