Biomedical subjects

Alan Chaikovsky

Publications and source records attributed to Alan Chaikovsky.

4 recordsLinked to original sources

PubMed2005

The evidential value of distorted and rectified digital images in footwear imprint examination.

The procedure for forensic photography requires that the film plane be parallel to the taken image. Another procedure must be used when the print is located on reflecting surfaces such as vehicles, or faint marks on porous surfaces. Examination was made of the evidential value of footprint images received from the scene or taken deliberately at an angle out of proper perspective (i.e., the lens axis is not perpendicular to the target plane). An artificial target was prepared and photographed from several lens axis angles ranging from 10 degrees to 85 degrees to the perpendicular, and then rectified using the Adobe Photoshop Version 7.0. It was found that at angles less than 40 degrees , the shape and location of all the individual characteristics were similar enough in comparison to the original image. In images taken at higher angles, the original image could not be adequately restored. The full potential of this image, therefore, could not be achieved after rectification. The results of this study show that the images of a footprint taken at an angle less than 40 degrees , preserve the evidential value of the unique characteristics.

Forensic Medicine↗

PubMed2005

Genipin, a novel fingerprint reagent with colorimetric and fluorogenic activity, part II: optimization, scope and limitations.

Genipin, a hydrolytic product of geniposide extracted from gardenia fruit, was thoroughly studied as a potential fingerprint reagent, and optimal conditions for fingerprint development have been determined. Latent fingerprints on paper items that have been treated with a non-ink running formulation containing 0.17% of the reagent, showed up as both colored and fluorescent images. On brown wrapping paper and on papers with highly luminescent backgrounds, genipin developed more visible and clearer prints than did classical reagents such as ninhydrin or DFO. Another potential advantage of genipin is that it is totally harmless and an environmentally friendly reagent.

Aza Compounds↗

PubMed2003

Deciphering indented impressions on plastic.

The questioned document laboratory is often called upon to decipher writing that has been erased, obliterated, or that has faded. In cases like these, the original writing is no longer legible to the naked eye, but may be enhanced using various light sources. Certain remnants of the ink's components absorb into the substrate's fibers and can be visualized, usually as luminescence or absorbance. A case is described here that involved the theft of a credit card. An empty plastic credit card holder was found in the possession of a suspect, and as submitted for examination. Indented impressions could be discerned on its clear plastic window and presumably originated from the credit card that had been held in the envelope. These indented impressions were deciphered in the hope that they would reveal enough details from the credit card to establish a connection between the plastic envelope and the stolen credit card. With methods generally utilized in the toolmarks and materials laboratory and the photography laboratory of the Israel Police, most of the indented impressions on the plastic were deciphered and a connection between the plastic envelope and the stolen credit card was demonstrated.

Journal Article↗

PubMed2003

Color separation of signature and stamp inks to facilitate handwriting examination.

The questioned documents laboratory often encounters cases where handwriting that is to be examined intersects with some interfering factor such as a rubber stamp, typewriting or background printing. In these cases, line direction, beginning and ending features of letters and other fine details of the handwriting may be lost in the "noise" of the intersecting ink. The purpose of this paper is to show several new digital photography methods that may be used to "subtract" the effect of the intersecting ink, thereby enhancing that of the handwriting ink in order to enable the document examiner to conduct a complete examination. These methods have the advantage of being fast and do not involve the use of expensive material or equipment. Several new methods are described that may be used to separate the colors of the handwriting ink from that of the intersecting ink: the analog method and several digital methods such as RGB-HSB-CMYK, L*a*b color, and color separation using the Channel Mixer function of Adobe Photoshop. Successful application of these color separation methods to specific handwriting ink/rubber stamp ink color combinations shows that the effect of the intersecting ink may indeed be minimalized if not canceled altogether. Application of the suggested methods may well make the difference between a nonconclusive handwriting examination and a full analysis of the questioned handwriting.

Journal Article↗