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Digital cameras in criminal cases on-site application

In Electronic Infomation Category: D | on September 30,2011

Summary: The camera records in a digital camera, collection, extraction and MAX472CSA datasheet and fixed traces of evidence, etc. showing the superiority of the traditional camera can not match. With the growing maturity of digital camera technology and MAX472CSA price and product upgrading, it will be more extensive range of applications.

criminal and MAX472CSA suppliers and computer technology along with the rapid development of technology department of criminal police authorities gradually realized the whole process of criminal digital camera. Digital camera photo recording, collecting, extracting and fixed traces of evidence, etc. showing the superiority of the traditional camera can not match, not only to reduce the traditional criminal photography and other chemical processes at the wash, and avoid environmental pollution and improve the criminal photographic work efficiency.

one digital camera and how it works

digital cameras, also known as digital cameras, this camera is the crystallization of new technologies of modern technology. Traditional camera through the lens to focus an image on photographic film, and then after developing, fixing and a series of processing, the image appeared in the film and fixed. Digital camera and traditional camera film from the biggest difference is the camera disappeared, replaced by a CCD (charge-coupled device) or CMOS sensor devices and digital storage devices, which only a small part of the CMOS camera, this paper is to discuss the use of CCD (charge Coupled Device) digital camera.

can also be said, between the digital camera is a camera in between the camera and the camera. In the image display method, both the digital camera directly to monitor machine screen display, but also high-resolution direct printing of photos. The use of silver in the shooting without film, the camera, the CCD or CMOS through photoelectric conversion, but the camera image display is limited to monitor or television screen. Therefore, a set of digital camera photos and camera high definition signal transmission in one of the advantages of convenient camera. In addition, the digital camera can also capture images for later processing, by telephone or network transmission, etc..

digital cameras not only in news reports, scientific research and other fields has a very important role in criminal science and technology also play an important role.

Second, the criminal case for digital photo camera site equipment requirements

135 black and white traditional film shooting scene photos, the resolution of domestic films in the 80 - 120 lines / mm, and the average of 100 lines / mm, according to national standards take the resolution of criminal photographic film not less than 75 lines / mm. If the above data into pixel digital camera, the relationship between them is 100 lines / mm is about 8.6 million pixels, 80 lines / mm is about 5.5 million pixels, 75 lines / mm is about 4.85 million pixels. In fact, the traditional process of making photographs in the darkroom, because the conditions can not fully meet the requirements, the final out of the picture quality is lower than the same pixel digital camera photos. 3.1 million pixel digital camera images of the largest 10-inch photo can be made, and the image is very clear. Of course, conditional units can be equipped with good quality professional grade SLR digital cameras, it can take into account the existing camera lens, where the infrared camera is better. Under normal circumstances, to buy universal 4-megapixel camera will more than meet the requirements of on-site photo shoot.

three digital cameras in the scene in a criminal case the advantage of

(a) digital photo production, processing convenience.

Unlike traditional photography digital photography as the need for darkroom processing, as long as the images downloaded to your computer, you can preview the picture using image processing software to crop, adjust. As with some special software, can also be false color coding, digital filtering, image processing for enhancement of traces automatically matching, automatic fingerprint identification, for fast retrieval of image data, the need to print photos, Some digital cameras can even be directly connected printer.

(b) digital image transmission, use quickly.

for major cases or cases of multiple sites, site survey can be taken to the scene pictures transmitted over the Internet to facilitate the leadership and command and decision-making, fast track suspects or to obtain relevant information for investigating this case to gain time. In the computer storage of digital images, store, retrieve, save, copy, and calls are very easy to photograph for a long time to save not fade.

(3) To facilitate the UV, IR special photo.

ultraviolet, infrared, visible light camera photo not available with the characteristics, it can not be taken to observe in the visible traces of physical evidence, in camera evidence examination is widely used. However, the traditional infrared, ultraviolet camera must have special equipment, methods, complex, high-performance requirements, such as a digital camera, is very convenient.

four digital cameras in use in criminal photography

(a) applied to on-site photography.

use of digital cameras using conventional photographic method according to the procedure of the crime scene location, and profile, the center and the breakdown of the film fixed. When taking pictures while shooting, while look at the photographic effect, not satisfied with the photos from the camera can be removed at any time, re-photographed. After the camera into the computer photo editing and appropriate treatment, stored in the computer disk, or in the field through the network transported to a photo processing center image, the image processing center as required to use filing system arranged for multiple photos , marked, with text after the printing device with a high-resolution photo print will set the scene. The site can also serve as a photo file in the database, once the need to re-tune the use.

(B) used in photographic evidence.

If you are using a film camera to shoot, then by selecting the extension rings or bellows, or use with a macro function macro lens to photograph professional to ensure that no deformation to obtain best may be a larger image and more details. Even in the faint traces of the shooting, the adjustment of the camera image is not ideal, post-production digital camera can use image enhancement technology to remedy. Traces of evidence using traditional techniques to determine camera photo effects can only wait until the film wash out, and use of digital technology can always look at image quality, according to the need to change conditions and make timely adjustments camera, greatly reducing the production cycle of photographs, trace evidence to be timely inspection and identification. Digital camera technology can set the camera for the proportion of traces of evidence, determination of traces of evidence on a computer the size, depth and orientation between the feature points, distance, to be compared with the sample data to make scientific conclusions. Digital technology also used to optimize the quality of the photographs, blurred treated to increase clarity, contrast through small adjustments can improve the tone contrast, have a colored background traces can change the background color to a clear visible signs, to color separation photography purposes.

(c) applied to identify the photo.

storage capabilities of digital camera library of favorable conditions, can quickly compare features of a human face record, personal characteristics. But also long-distance transmission through computer networks, to the investigation of criminals, suspects or to identify unidentified bodies brought great convenience.

investigating this case in favor of smooth, but also significant savings in manpower, material and financial resources and time. Police use of digital technology according to witnesses describe the production of analog photos of criminal suspects; the corrupt body of facial photographs entered into the computer to simulate the face of the deceased photographs for identification; for facial injuries and even the bodies of the skull can be treated similarly . Identified as the overlap in the skull, can be identified to remove the background picture, improve image quality or partial homogenization treatment, eliminate the poor picture quality caused by the identification error. In the combination of portrait, because the digital images combined with images, paste function, reduced contrast due to the artificial combination of portrait uneven, poor symmetry factors of error, the image quality to identify a substantial increase in accuracy.

five digital cameras used in the legitimacy of Criminal Science and Technology

(a) of China! Code of Criminal Procedure? Article 42 provides:

"to prove the truth of the case all the facts are evidence."

This is the law of evidence in criminal proceedings under the definition. Evidence has two basic properties of features, one of objectivity, is the existence of the facts, not speculation and false things; second is relevance, with the objective facts of the case is linked with the facts. Criminal evidence in criminal proceedings, the public security and judicial organs collected, or by defense lawyers, private prosecutor and other law made, whether the facts to prove the crime occurred, the suspect, the defendant is guilty and the case the real situation of all the facts.

and application of digital photography capture traces of evidence handling by the public security organs according to law and evidence collection procedures and obtained, obtained mainly through its site investigation, mainly in their respective examinations and types of evidence notes, conclusions, they play a role in the investigation stage is the role of clues, evidence in court is the trial stage role. Application of digital photography capture traces of evidence in criminal processing technology as a means of investigative measures and a concrete manifestation, so the legitimacy is conferred by law.

(b) strengthening public security organs of the criminal department of the technical equipment technology and operations management to ensure the application of digital photography capture traces of evidence dealing with legitimacy. First, the development of technical practices. Technical operation of the equipment constitutes a (hardware and software), quality of personnel, specific operational procedures (including the original backup, operating skills, standards, and file retention), organizational management, discipline, etc. should be standardized and strengthen management. Second, configure the digital image capture system science, enhance efficiency. Third, to strengthen the criminal photography professionals, business training and improve the level of technical operations.

(C) from intervention through legislation on the legal system, constraints limit the application of digital photography film processing traces of evidence, legitimacy under certain conditions. Application of digital photography shooting the final traces of evidence is handled in court as evidence, its legitimacy should be given by the law judge, the question for the lawyers, the prosecution of the respondent, should # be based on facts and law as the yardstick? . Therefore, the meaning of democracy and legal system, through the legislature to strengthen legislation to regulate the use of the principle of burden of proof, under certain conditions, limit its legitimacy, it is very necessary.

six digital cameras are replacing traditional cameras

the current situation, digital cameras and traditional cameras, there is still inadequate. First, the shutter lag, in the shooting incident, moving objects, prone to take failure. Second, continuous shooting of digital cameras, the number of sheets and continuous shooting speed than conventional cameras. Third, start slow and not conducive to the capture. Fourth, the resolution of a digital camera at this stage is still less than the high quality of traditional film. For example, using Kodak T - max100 other professional film, with a resolution up to 200 lines / mm, converted into pixels of 34.56 million, while today the best digital cameras resolution for 2000 was more than one million pixels, a far cry.

in criminal cases in the field camera, digital cameras and traditional cameras can be used together, especially in the overview camera, key parts of the camera, you can also use high-quality film shot some pictures, when found Investigation of the site have been ignored important evidence, you can film for high magnification of objects, but the digital photo for the local high magnification, the image is not easy to get clear.

proved, with the maturing of digital photography and digital cameras to upgrade the product, compared with traditional film photography technology, its advantages become more prominent, wider range of applications.

in the security business in photography, digital photography as an update of traditional film photography is an ideal way to become a crime scene fixed, physical security certificate card, record the assessment process and conclusions of the new ways and new means and new methods.

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