Fingerprints on the wooden floor and the discovery -

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Fingerprints on the wooden floor and the discovery and extraction

, Available multi-band light source, choose the appropriate wavelengths to search; surface of dusty wooden floor, a strong light source can be used (such as site inspection lamp) irradiation observed, can be a variety of angles, but the side light was better. Fourth, the extraction of fingerprints on the wooden floor under normal circumstances, the extraction of fingerprints on the wooden floor and smooth paint surface can be the same types of fingerprint extraction methods, such as direct camera extracted directly sticky tape extraction, extraction of electrostatic photocopying or appear before extraction method, when necessary, can also extract original local wood flooring. But traces of wooden floor surface is complicated, difficult to find fingerprints, in order to get better extraction efficiency, the method can be used to extract some special, some of which can be found at the same time extract. Common methods are: (a) UV reflectance photography. General use short-wave ultraviolet light, because most wood flooring ability of UV-absorbing paint surface becomes dark tones, while the sweat fingerprints on the UV reflectance strong, then the background image in the following fingerprint at the same time to eliminate or reduce interference, The contrast with the large hand-stamped line, taking pictures better. (B) UV-fluorescence photography. Applied to the surface cracking or rough weathered wood off the ridge on the floor, obscure fingerprints from. Paint in the short-wave UV light, emits strong fluorescence, while the sweat in the same light source fingerprint ridge the fluorescence intensity is weak, so that the sweat and paint ridge result in higher surface brightness difference. (C) after the pictures appeared sulfur acid extraction of hydrogen. Wood dust and fingerprints appeared on the floor, especially a mixture of sweat and dust the case of fingerprints more of such fingerprints can be revealed by sulfur acid, hydrogen, making hand-stamped into a brown line, enhance the contrast and then photographed extraction. (D) multi-band light source light-induced fluorescence photography. Left in the multi-color mixing, texture patterns on the wooden floor of complex latent fingerprint, can be multi-band light source in the 450nm or 485nm wavelength of the light output radiation, using fluorescent powder brush and camera were extracted. (E) Extraction of color photography. This method is by changing the light source spectrum or photosensitive layer of photosensitive material properties, change the tone by making objects, enhanced contrast, highlight the hand-stamped line, and eliminate or reduce the background color of wood flooring and a variety of texture patterns of interference. Specific use, the available filters, multi-band light source and so on. Latent fingerprints of sweat or blood, can be treated with DFO method, and then color camera multi-band light source extraction, the better. Fifth, with the fingerprint image processing technology to eliminate the interference of the background color of the photo on the wooden floor fingerprint extraction method, although there are several, but the camera still is one of the main extraction methods. Because the background color photograph stamped line interferences opponents, so the picture is not easy to see the line features hand-stamped, the test is not conducive to use of fingerprints. In this case, you can use computer image processing technology, hand-stamped photos to correct line and background color contrast, stripping wood and patterns to make hand-stamped lines clearly visible. Computer image color correction mainly through the image contrast and color level adjustments to achieve. To do is: first photos through the scanner scans fingerprints into the computer, the conditional direct capture digital camera can be used to generate digital image files, then use the Photoshop image-processing software Image / adjustment orders for digital image processing, adjust the color of the image color,[link widoczny dla zalogowanych], brightness and contrast and other parameters, separating the background color, background texture pattern to eliminate the interference of rival stamped lines. For example, Figure 1 is a composite wood floor surface fingerprints left on-site photo image processing using Photoshop, select , move the eyedropper choose the background picture fingerprints (ie, wood floor surface) color, and adjust the color according to the specific volume difference (generally better tolerance margin slightly larger), and then adjust the brightness change slide settings area block to the maximum, and finally select To point out that, Photoshop images at the scene fingerprints Figure 1 Figure 2 photos pictures after the fingerprint management software also has some limitations, it can not completely eliminate the surface of the wood and the wood floor of the fingerprint patterns of interference.

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