Tattoos have been an invaluable method for the id of non - skeletonised remains. The look and/or located area of the tattoo can be significantly exclusive to provide enough identification, and particularly when combined with other distinguishing features they can definitively identify and specific.
During an autopsy the pathologist will need note of tats just as they might other distinguishing markings, such as beginning marks, defects or marks. In situations such as mass disasters, it can often be one of only few methods available for the initial examination of the remains. In 2001, Kingsholm et al studied several unidentified physiques and remains within Danish waters, a few of which had tats. Discovery and detailing of any tattoos can also assist in tracing unidentified body back again to their cultural backgrounds, thus in some cases tattoos have important historical aspects.
Tattoos can also indicate a brief history of incarceration (Mallon et al 1999) and in such instances the individual sporting this unique design may well not desire to be easily discovered. Repeat offenders for example, might want to remove or change their defining features and participants of gangs or organised offense groups may decide to no longer be associated with that particular faction. Some tattoo designs may serve to connect one individual with another, such as 'love' tats, which can also aid in identification of the average person sporting the design.
Different light options and filtration techniques have been used consistently in unlawful investigations; the next uses of infrared (IR) picture taking provided in this intro are all relevant to this analysis as each goes some period towards explaining the nature of infrared and for that reason what might be likely, enabling deduction of any hypothesis which is offered later in this statement.
Infrared details the area of the spectrum just beyond the noticeable red wavelengths (700 - 1200 nm)
There are many used of infrared picture taking spanning various fields.
For art photography purposes, Infrared can be used to photograph items in the length, or in foggy conditions because of the infrareds potential to penetrate the haze (Milsom 2001). For family portrait photography, infrared may also be favoured to give the appearance of any clear complexion
Infrared's (IR) capacity to permeate the superficial layers of the skin of pores and skin is exploited in medical photography as a method of photographing venous patterns underneath the skin area and of documenting recovery under lesions in the skin. They found that imaging in the near-infrared range provided relatively good compare of subcutaneous veins. This works due to the fact that haemoglobin is a chromophore that absorbs near infrared, and the skin absorbs hardly any IR in accordance with the absorption of infrared shown by the veins (Haxthausen, 1933), or transmits or displays most of the next to infrared spectrum, so that it appears lighter in comparison to the darkened veins.
Zharov et al (2004) discovered the potential of the technique as a diagnostic method for varicose veins at a depth of 1-3mm in to the skin.
The use of infrared picture taking for the recognition of varicose veins or any other subcutaneous abnormalities is showed by Marshall (1981). This research uses infrared reflectance (as well as ultraviolet) to gauge the densities across pigmented lesions of your skin and found it to be always a useful method.
The research by Haxthausen (1933) discovered that for documenting superficial afflictions, such as psoriasis, typical photography was much more advanced than infrared picture taking, as under the infrared conditions, the imperfections were removed. Afflictions that occurred in the deeper layers of the skin were captured best using infrared picture taking.
In circumstances of burn damage is can be difficult to determine the damage or the thermal burn up depth. Anselmo et al (1976) found that infrared photography could be used as a very important and non invasive approach to assess burn up depth. Their test used Wratten 89A infrared filtration system Infrared photography allowed for the differentiation between practical and necrotic dermis.
Infrared picture taking of bloodstains and Gunshot residue
Forensic applications of infrared photography include detecting gunshot residue on clothing (Bailey et al 2007) and less commonly, for detecting bloodstains on dark clothing or at crime scenes. A written report by Raymond and Hall in 1986 illustrated a dark colored sofa, showcased in the survey as a black and white photo for the visible spectrum comparison. On this photograph there is no clear bloodstain, it cannot be distinguished from all of those other sofa due to the dark color of the sofa. The infrared picture was taken using the Wratten #88a filter. In this photo the sofa possessed lightened and today by comparison, the area of bloodstained couch (now darkened in comparison) could easily be distinguished.
When using infrared photography to identify and record traces of bloodstream on dark clothing, the infrared will make the blood seem darker and the encompassing clothing show up lighter by contrast. This is all due to the absorbing capacities of the clothing and of the blood. Bloodstream absorbs throughout the obvious spectrum and the near infrared spectrum (typically absorbing most wavelengths of in close proximity to infrared 700-900nm) therefore its appearance in infrared records will be darkened, on the other hand the clothing might only absorb through the noticeable light range of the spectrum, and so in the infrared information will appear lighter, or transparent.
Dark clothing can hinder the successful visualisation of bloodstream spatter habits in quite similar way that darkened mummified skin can hinder the diagnosis of tats, or that charring on the fire damaged document can affect the successful visualisation of the writing. A study by Perkins (2005) used digital infrared photography, Wratten #89B filter to photograph bloodstream spatter on a number of different materials. The dark clothing seemed to reflect the infrared, thus enhancing the contrast between the clothing and the blood patterns.
Bailey et al (2007) used digital infrared picture taking to raised visualise gunshot residue on dark clothing. It is very similar in both strategy and leads to the use of this technique in bloodstain analysis. The camera ISO was place at 200 and the filtration system used was the Wratten #87. The GSR, undetected under noticeable light conditions, appeared dark against a lightened towel under IR.
The use of infrared in examination of obliterated writings and questioned documents
Infrared photography also offers many applications in the field of forensic research.
It is a common method for detecting obliterated writing (Creer 1976) for detecting forged, or altered documents, such as cheques and assist in the study of writing obscured by charring burning broken documents (Bartha. 1973)
McCaul et al (2007) discuss the issues facing forensic experts when traditional photography techniques flunk at documenting certain evidence. In the study of documents, IR may be used to discover forgeries or modifications, relying on the fact that the visually similar inks may reveal or absorb infrared at differing levels and wavelengths.
Parallels can be drawn between the uses of infrared for examining obliterated writing and this study into analyzing original body art from underneath cover tattoo designs. The use of correction fluid or other inks to hide writing serves to provide the underlying wording illegible, in the same way that the cover tattoo serves to distort, hide or completely cover the initial actual tattoo. If infrared photography makes it possible for for the primary writing to be visualised, than it is completely possible that root original tattoo could be recovered. The successful restoration of obliterated writings is dependent on the several inks used and their infrared absorbing capabilities. Some ink, when irradiated with infrared, will absorb it. That is because of the occurrence of different Chromophores in the various inks (Ellen, 2006)
A chromophore is the chemical band of a molecule that is in charge of the molecules color, and they absorb, reflect and transfer different wavelengths. Other for example chlorophyll, melanin and amethyst.
Infrared photography can even be used to take a look at/restore writing on charred documents (Bartha 1973). The success of the visualisation is dependent on the degree of charring. The charred paper is darkened scheduled to partly altered resinous material before being completely degraded to primary carbon. The carbon in the pen ink absorbs the infrared therefore looks dark under IR, in comparison the charred newspaper looks lighter. The Video recording Spectral Comparator (VSC) is often used in the examination of obliterated writing (G M Mokrzycki 1999). The VSC uses Infrared glowing energy and filter systems to look out of inks and other obliterations, and reveal obscured objects. The usage of infrared picture taking is not an uncommon method for visualising and saving obliterated writing, S. Sugawara (2004) talks about the use of both close to and middle infrared in deciphering obliterated writings by looking at writing made by 101 different pens.
Erasures describe inks which may have been made invisible by removal of the color the different parts of the inks. Sometimes when these components are removed, remnants are left behind. Sometimes whatever remains on, or just below, the surface can be found using infrared. This is actually the same principle experienced in a newspaper by McKechnie et al (2008) where infrared was used to discover remnants of ink left behind in your skin post-laser removal treatment. The findings of this research will be analysed in greater detail down the road in this research paper.
Other uses of infrared photography
The uses of Infrared photography do not get started and end at medical and forensic uses however, for example, Bridgeman and Gibson (1963) used infrared to look at paintings.
A newspaper by J R J Truck Aperen De Boer (1969) successfully applies Infrared Reflectography to see the under-drawings of carbon pencil, with varying levels of success of middle ages paintings.
Pencil business lead (which is generally graphite) absorbs throughout the infrared range of the spectrum, and the noticeable range. As a result of this, under both near and significantly infrared conditions the graphite will stay as conveniently viewable regarding the naked attention.
Thus significantly this task has looked at both medical and forensic uses of infrared photography, many of that have in keeping the idea that infrared can be used to recover, or discover traces of 1 material (for example; ink) from underneath another material (such as correction liquid). These underlying or otherwise 'camouflaged' materials aren't commonly viewable with the naked eye, or easily documented using regular photographic methods. This is actually the same rule as is usually to be used in this research.
The detection of latent residue tattoo ink pigments
The use of infrared picture taking to record tattoos is in no way a recent trend. As long previously as 1938 J¶rg used infrared photography to discover tattoos which were in any other case undetectable with the naked eye.
Although infrared photography has been useful to study tattoos, there isn't significant amounts of literature on this issue. Below some specific good examples are given. Listed below are 2 examples found provide useful validation of infrared penetrating features coupled with its specific use for detecting tattoo designs which may have been afflicted by environmental conditions, or purposefully made difficult to visualise:
Mckechnie et al use infrared photography to try and visualise latent tattoo ink residue from laser beam removed tattoos.
This research article only used 2 participants, and with successful rate of 50% and so a follow up experiment would be required using a much larger sample size to validate the results. Both participants possessed their tattoos removed by laser treatment to the extent that these were no longer obvious to the naked eye. Among the individuals' tattoos was professionally done; the other was an amateur tattoo. However the authors describe the difference between novice and professional tattoo designs just as one factor (that is the fact that professional tattoo designs use more ink and are injected much deeper in to the dermis than amateur body art) and mix guide it with infrared's capacity to penetrate your skin, they don't expand on the color or pigment as being factors resulting in the success or failing of the trial.
Visualising tattoos on mummified remains using infrared photography
One of the initial journal articles of interest that may be said to have initiated the idea behind this task idea, or at the minimum inspire a belief of the success of the job, uses infrared Reflectography to examine body art on mummified remains, the mummified tissues normally being darkened to the amount that visualisation under normal photography conditions is near impossible (Alvrus et al 2001) It showcases the usefulness of infrared for lightening certain aspects of a subject to be able to see others. In cases like this, the darkened mummified muscle made it difficult to visualise the tattoo under normal photographic conditions (visible light). Under Infrared conditions however, the compare between the tattoo and the surrounding skin was improved; the darkened mummified pores and skin made an appearance lighter, and in comparison the tattoo (which came out darker) was quickly visible. That is because of the differing absorption/representation of infrared. The substances in the tattoo absorb a lot of the infrared; the surrounding skin area reflects the infrared.
A similar technique is used in the id of tattooing on a 1600 calendar year old mummified body found in Alaska (Smith and Zimmerman 1975) Tattooing was identified on the hands and forearms of the Eskimo woman remains using infrared photography. The darkened skin area obscured the tats to the extent that they could not be viewed under obvious light spectral range photography.
Skin thickness as a factor
One of the other variables accounted for in this project is the area on your body of that tattoo, the idea behind this being that the thickness of your skin might enter into play. According to E J Timber (1985) the thickness of the skin amounts from 0. 06 - 0. 1mm (from eyelids, to back again and callused areas, respectively). The dermis varies from 2 - 4mm thick, and makes up about the majority of your skin. Although any differences in epidermis depth have a tendency to be minute, they may still take into account variable success rates due to the migrating aspect of tattoo ink through the dermis and the penetrating capacities of infrared. An experienced tattooist will not permit the needle to permeate the skin no deeper than 2mm, the reasons for which are discussed below in 'The tattoo process'. The ink must be deposited deeper than the skin, if not the ink will fade as the external layers of your skin shed, which means thickness of the skin will have an effect on how profound the ink must be transferred. It is also assumed that the thickness of the dermis will correlate with the thickness of the skin. This is why this research paper has chosen to check out the area on the body of the tattoo just as one factor.
The tattoo process
The process of tattooing involves injecting pigment, suspended in a carrier, through the skin and into the dermis of the skin, no more than 2mm or else the tattooist risk the ink bleeding, creating a smudged effect, regardless of the tattoo technique used (the adjustments of the modern tattoo machine don't allow for the needle to permeate any deeper than 2mm). There is absolutely no exact science regarding the pressure exerted on the needle by the individual tattooist, as it is a subject of personal judgement (immediate quotation from Make - tattooist from Danny's tattoo Studio in Sneinton, Nottingham) depending on the area of the body which the tattoo is being performed. Tattooing on a person's back or higher arm will require higher pressure because the skin is much thicker, the setting up of the tattoo machine will also have to be improved for deeper penetration through the skin and in to the dermis.
Once injected in to the upper layer of the dermis, the pigment is suspended in the fibroblasts (Sperry 1991). When looking at a tattoo, the tattoo is being viewed through the epidermis.
Over time the transferred tattoo ink will disperse deeper into the dermis, therefore it's possible that time, both between original and cover, and time since cover, could be a feature in the investigation.
Tattoo Ink pigments
More often than not, the tattooist will use a tattoo ink containing pigments which is manufactured beyond the tattooist's own premises, the exact content and purity of which is in most cases, unknown. There are specific guidelines set up for manufacturers of tattoo inks to follow when producing the inks, however manufacturers of tattoo ink aren't forced for legal reasons to reveal the ingredients used in the inks. A study by Timko et al (2001) discovered that, of 30 inks researched, the most commonly discovered elements were aluminium, air, titanium and carbon at 87, 73, and 67 percent respectively.
Professional tattoo artists have access to over 100 different colours (Kirby et al 2005), many of these are mixtures of shades, for example red and white to make green, thus rendering it difficult to classify pigment-wise. The study by Kirby et al (2005) found significant variability in pigment cluster sizes in professional body art, in comparison to amateur tattoos. They also found shade pigment granules to be bigger than dark-colored pigment granules.
This was initially an area appealing, but not one that this research paper will concentrate on due to the difficulty encountered in obtaining the relevant information.
This research uses infrared photography in an attempt to visualise a genuine tattoo from underneath a cover tattoo, the success which could be credited to a variety of factors. A summary of these factors are as follows:
To look at the colours found in both the original tattoo and the cover tattoo and exactly how this impacts the successful visualization of the original tattoo using infrared.
To look for any relationship linking time since cover tattoo (current of picture) and success of the experiment. This essentially will be looking at the consequences of the migration of tattoo ink.
To take a look at any trends concerning time elapsed between original tattoo and cover tattoo, and the success of the infrared photographs obtained. As above, this will be analyzing the consequences of ink particle migration.
To look at the area on the body of the tattoo and find out when there is a romance between this and the success of a particular photograph. Essentially, this is exploration epidermis density as a factor.
Taking into consideration all the research discussed recently and the results obtained by the many studies in neuro-scientific infrared picture taking a few hypotheses have been deduced:
The first would be that the penetrative dynamics of infrared suggests it is possible to recover the root pigment of the original tattoo from beneath the cover tattoo. The reason why behind this are thought at this time to be because of the colours present, or simply even the concentration of black used in the colour mixtures.
The manner in which an object looks when photographed using infrared is a direct consequence of these absorbing features.
For the purposes of this particular study inspiration was drawn for the study into questioned documents, or more specifically the diagnosis of different inks using infrared. Most inks have different absorbing functions, some will only absorb through the obvious light spectrum, and some throughout the visible light and in to the infrared range. The real reason for this, as mentioned earlier, is because of the chromophores in the dye substances.
In the same manner that infrared might be used to find the underwritings of obliterated content material, IR could be used to discover the root tattoo pigment, depending on chromophores, or shades used.
The second hypothesis is the fact any variation in the depth/thickness of your skin will be such a minute difference that it's unlikely to impact the overall success of the task.
The factors of your time (time between original and cover, and time since cover) will probably have minimal result, if any, on the successful aesthetic restoration of the main tattoo. It is thought that any tendencies are more likely to be viewed in the extreme time periods, for example, between tattoos that are under a time old and tattoos that are over 30 years old. It is because the most recently done tattoos will not have been afflicted by migration, whereas very aged tattoos will have been subject to years of migration of the ink particles.
Method and materials
A sample amount of 33 (n33) individuals were found in this research, most of whom volunteered their time and consented for the demonstration of their tattoos anonymously in this research newspaper. All those things was required of potential participants was that they had a cover tattoo, there was no other requirements chosen for, for example time or gender. The members were then necessary to complete a consent form, as no photos could be taken without. The members were asked to fill out a short questionnaire to assist in analysis of the various factors talked about in the introduction, an example of that can be within the appendix.
This task utilizes the in close proximity to infrared area of the spectrum (the far infrared area of the spectrum is often used for thermal imaging). The infrared filters allow infrared light to feed the camera and blocks the majority of the noticeable light spectrum.
The Fujifilm IS expert digital SLR camera is sensitive to both ultraviolet and infrared light between 380nm and 1000nm.
Optimum settings for the camera were assessed during several pre-experiments. Manual setting up, ISO 200 and aperture f/6. 3, which provided adequate depth of field for the infrared photographs
Filters 87 and 88a were used, which can be described as deep infrared filtration systems; allow no visible light to feed.
The Wratten 87 filtration system has a well-defined cut-off at ~800nm, and so transmits freely throughout the infrared region.
The 88A has a somewhat narrower window with a highly effective cut-off at ~750nm.
The control images were taken utilizing a UV/IR barrier filter.
All photos are considered at a 90 perspective from the topic (as close to as you can without actually measuring the exact position) this was to eliminate any fake positives due to raised body art (which can happen in hot conditions).
A colour level, a grey scale and a sizing size are held in place throughout the tattoo.
The first photo considered is the control photograph, using the IR-UV cut lens. This allows noticeable light to be captured and so essentially, is just a normal (visible light) adobe flash photography picture.
The second photograph gets rid of the UV-IR slice lens, updating it with an IR filtration. The first used is the Wratten 87, as much images as necessary are then taken using this filter. The third group of photographs is considered with the 88a IR filtration system.
The Metz 45CL4 electric adobe flash gun was the light meter of choice, the setting which differs between images depending on the light source available at the positioning.
A quantity of photographs were considered of every tattoo; one control photograph, and 2 images using each filtration. The first infrared photograph was to capture the entire tattoo, like the scales. A second photograph was taken if regarded necessary, which was a up close shot, focussing on any regions of interest outlined in the first infrared photo in order to capture better aspect.
Once all the photograph details were obtained these were classified into 'successful' and 'unsuccessful'. With the successful results, because of the varying degrees of success encountered from record to record, it was felt necessary to categorize further still with the release of a grading system.
The grading system is as follows:
0 - Nothing of the initial tattoo could be visualised
1 - Partial original tattoo visualisation
2 - Most of original tattoo can be seen
3 - All of the original tattoo is seen from within the cover tattoo.
Please remember that a few of the images offered in this record have only undergone basic alterations post production. The changes made to the infrared images were limited by minor lighting and comparison changes to accentuate any depth in the pictures that might have been lost when the images were resized and in order to retain depth in the paper hard backup. These changes are as follows:
Brightness was transformed to no more than around -10% for the infrared images on Microsoft Office Word 2007.
Contrast was changed to a maximum of +30% on Microsoft Office Word 2007.
These principles are approximate, and determined by the detail captured in the initial, unaltered images. The images were not altered in any other way
The underlying tattoo can be somewhat visualised under visible light picture taking conditions however visualisation of the original tattoo is accentuated using the Infrared as it cleans away the camouflage or interference provided by purple shading of the cover tattoo. That is a level 2 example.
This was graded as 2 because a considerable amount of the original tattoo can be retrieved. In this case, the tattoo, under noticeable light conditions, is not an obvious cover tattoo as no detail of the main tattoo can be found because of the use of shading and the faded mother nature of the initial tattoo. Using the shading of the cover tattoo removed using the IR filters the details in the initial tattoo can be visualised. The dark shading of the cover tattoo on the eagle's head and wings is not aesthetically removed by the infrared, and so part of the cover tattoo continues to be camouflaged.
Note - The dark renewable and blue of the original tattoo appear darker in the infrared than the other colours of the cover tattoo. The purple in the backdrop has completely disappeared in the infrared photo.
This is an especially interesting record as it shows the absorbing capacities of black ink. Although some of the initial design can been observed in the control photo it is relatively polluted by the dark shades of the cover tattoo. The blue and especially by the purple of the cover design are visually removed in the infrared photo, highlighting the contrast and allowing for better willpower of the genuine design.
It would be likely that if there were a trend between these results that as enough time since the cover tattoo boosts, so would either the success or inability rate. At the same time, the remaining (factor - either success or failing) would lower as the other increases to show that there surely is a clear correlation. This does not occur, therefore suggests that there is no link between time because the cover tattoo, and the overall success rate.
Also there will not look like any detectable style in the observed graph patterns between fig. 9 and fig. 10
A summary stand of data, including home elevators shades used, the level allocated to each record, and a brief explanation of what is seen with each record, is available in the appendices (Appendix 4) the conclusions which are reviewed in the discussion section of this research paper
It should be noted that this graph only presents the number of cover tattoos with black ink in the design and will not take into account whether or not the dark ink is immediately accountable for the obscuring of the initial tattoo design. It can, however, present a slight trend, which is usually to be expected.
In cases where in fact the cover tattoo is colourful, the Wratten 87 filtration system appeared to be the filter of choice as it removed all coloring of the cover design to expose the underlying original tattoo.
In cases where in fact the cover tattoo contains cut black or grey shading, the Wratten 88a appeared to be the ideal filtration to better accentuate the initial design from the cover tattoo design traffic.
Of the unsuccessful samples:
The following results are characterised based on the observed reason the original tattoo could not be visualised. Please be aware that in 100% of the unsuccessful data the cover tattoo design covered dark-colored ink, however in some cases it isn't deemed to be the reason for unsuccessful visualisation (In some instances for example, the dark of the cover will not cover the original design)
Discussion
This research has demonstrated definitively that infrared photography may be employed to detect an original tattoo design from underneath a cover tattoo.
Of the several factors investigated in this newspaper that were considered to have an effect on the success of the restoration of the initial tattoo using the IR filter systems, really the only factor with any real merit were the colorings used in the initial and cover tats.
The time because the cover tattoo was investigated due to the behavior of the ink once transferred in the skin. As described in the tattoo process section, after the ink is deposited, over time some of the contaminants will disperse throughout the dermis. It had been thought that the effect of this, if any, would be to hinder any successful restoration of the main tattoo.
No obvious relationship was discovered between your time since the cover tattoo and the successful restoration of the original tattoo from within the cover tattoo.
Time between original tattoo and cover tattoo also yielded no evident connection to the success rate. The graphs and a brief explanation of the studies is seen in the results portion of this newspaper (fig. 18 and Fig. 19)
When considering the area on your body as a factor (essentially that is looking at the depth or thickness of your skin) it looked like necessary to take two instances from regions of differing skin width and compare the success rates from each.
The skin width of the wrist will be significantly less than the width of your skin on the back, which combined with the soles of the hands and feet, is one of the areas on your body of the most significant skin density. Of the results for the wrist tattoo, 50% were successful. This is exactly like with the results from the instances photographed on the back (Fig. 17) suggests that the area on your body of the tattoo acquired little if any bearing on the results.
As predicted it's the colours used in both the original underlying tattoo, and the cover tattoo, that has the most bearing on the successful visualisation of the original tattoo.
Visualisation of the underlying tattoo was most eye-catching and effective with the instances with purple, red, light blue and white cover tattoos - this is likely to be due to the different chromophores (the functional group of the pigment molecule that provides it its coloring) in the several colors used, as they will absorb or reveal the infrared wavelengths at differing levels. Red and purple cover designs yielded the best results because these shades were completely aesthetically removed by the infrared filter systems, departing only the underlying original tattoo apparent.
Referring to Fig. 1 and 2 of record 26, the purple of the cover design is completely visually removed under the infrared photographic conditions, allowing the black outline of the original root tattoo to be completely visualised.
Records 22, 26 and 26b are perhaps the best cases, each receiving level 3 in the grading system for complete visualisation of the original tattoos. The original designs can be easily recognized as there is no disturbance from any fragments of the cover tattoo left out under the infrared conditions.
Record 22 (Fig. 12 and 13) can be an example of a darker original tattoo design with a dark-colored outline covered with red and crimson ink design. The initial tattoo design in record 22 could be only slightly detected using noticeable light picture taking and electronic adobe flash, however the details of the designs cannot be visualised scheduled to deliberate shading of the cover tattoo. Under IR photographic conditions, the red of the cover tattoo appeared clear, and the fundamental design could now be viewed with no disturbance of the cover tattoo.
In Record 4b, the initial design was significantly faded dark-colored writing. Referring back to the work of McKechnie et al (2008) it is already established that infrared will find and emphasize faded or purposefully removed tattoo residue in your skin.
Record 4b also illustrates this, as the details barely detectable by the naked attention becomes significantly more legible using infrared filtration systems.
Of the 20 successful results, 100% of the information had black ink in the underlying original tattoos, be it block color, shading or maybe outline. In such cases as information 26 and 22 it was the dark outline of the original underlying design that was most dazzling in the infrared image. As mentioned previously, it is because the black ink absorbs throughout the near infrared range of the spectrum, and so any infrared that penetrated your skin and had not been absorbed by the many ink pigments used in the cover tattoo, would be absorbed by the black, and this would give a very strong successful visualisation. Dark-colored ink found in the cover tattoo would prevent the infrared from detecting anything beneath it (fig. 25)
Of the results graded 2 on the success size, roughly 72. 7% got dark in the cover tattoo. In those tats in which all of the original tattoo could be visualised, 0% experienced dark in the cover tattoo. On the results graded 1 on the success scale, 100% of the cover tattoos designs possessed an element of black ink, whether it is block shade, shading or perhaps outline. In the unsuccessful data (graded 0), almost all (about 66. 6%) were dark cover tats, although 100% of the results got dark elements in the cover tattoo however, in conditions such as where in fact the original tattoo is built-into the cover tattoo, it is thought that the presence of dark-colored is not the principal reason behind the unsuccessful visualisation of the initial tattoo. Please refer to the appendix 5 (the complete record collection)
Of the successful results, the varying levels of success were more often than not attributed to existence of dark-colored in the cover tattoo, which unlike crimson or red, remained strong in the infrared photographs.
Grade 2 records, in the majority of cases, stopped lacking complete visualisation (class 3) because of the presence of dark ink in the cover design that still obscured part of the original design. It is because the black pigment absorbs the infrared, and works in quite similar way as using infrared to decipher obliterated writings. The infrared penetrates the correction fluid and is also utilized by the root black ink (Ellen, 2006).
Second in the operating for reasons as to the reasons the experiments in such cases were unsuccessful was that the original tattoo design was integrated into that of the cover tattoo, which recommended that no matter any success in removal of colour under IR conditions, the design of the initial tattoo could not be readily recognized from that of the cover design. This makes up about 4 from the 18 unsuccessful results. For the remaining 2 cases in the 'other' category, the reasons for having less success was attributed to the utilization of similar ink colours in both original and the cover tattoo designs and so it was difficult to differentiate between components of both.
The other of the instances had had the original tattoo treated with 2 laser beam removal treatments prior to the cover tattoo.
The grey used in the cover tattoo designs is the dark-colored and white mixture or a lower black (diluted with distilled normal water) thus diluting the quantity of black pigment, that could provide a rationale as to why in some instances, under IR conditions, the gray cover lightens allowing the original tattoo, providing the ink which is darker, to be visualised more commonly.
In some instances, particularly where the original tattoo used dark or black ink included in a lighter tattoo or shading, the adobe flash conditions by themselves were sufficient to discover all or area of the original design.
There were a number of occasions where it was difficult to categorize the results:
Photograph 4b was a particularly interesting exemplory case of this. The cover tattoo did not try to camouflage the complete original tattoo, it was not necessary as the initial tattoo was sufficiently faded in order to make it difficult, while not impossible, to identify with the naked human eye. Although the original tattoo could not be visualised from underneath the dark-colored cover design, it performed serve to raised visualise the initial tattoo from in between the cover design.
Difficulty was experienced when wanting to categorize the ends in the grading system.
Record 16 was an interesting case in point for the complexity of categorizing the results. In this specific record, using infrared photography a rectangular form, or structure was found that had not been visible in the control record, however, the initial main tattoo design was that of any love heart, therefore it was assumed that the rectangular routine was an integral part of the cover design so that as no love heart and soul design could be detected, the record was graded 0.
Record 29 was another confounding example, as the cover tattoo was imperfect, meaning that the initial tattoo could be relatively viewed under obvious light conditions. The cover tattoo was some outlines with little shading, all in dark-colored ink. This supposed that the initial design was noticeable in both the control and infrared photos, and so difficulty was experienced in categorising this specific record.
A Compact disk of the individual records is roofed in this research paper (appendix 5)
Conclusion
There are a number of explanations why an individual should cover a tattoo, such as a want to keep a concealed past, to disguise affiliation with a particular gang or culture, to symbolically remove a earlier loved ones symbol, or perhaps more generally just to disguise any distinguishing feature that might make them immediately identifiable.
This research has demonstrated that using situations it can be possible to detect and visually recover an original tattoo design after the tattoo has been completely covered, using infrared photography.
Out of all the variables investigated in this paper, the only one with any merit appeared to be the colours found in both original and cover tattoo.
Successful visualisation was dependent on the chromophores in the ink, that are responsible for the pigment molecule's shade. These echo and absorb infrared at varying levels.
Black ink is well noted to soak up infrared, which is validated by the results of this job. In all of the documents, control and infrared alike, the black remained the most dominant element in conditions of colour.
The colours most readily visually removed in all of the infrared records were crimson and red, as they transmit throughout the visible selection of the spectrum, but represent all infrared radiation therefore although to the naked eye the purple shows up as solid block colour, and the look can't be seen underneath (details 26 and 26b) however, under infrared conditions the colorings appear transparent, exposing the concealed design.
Greens and blues, although removed by the Wratten #87 filtration, were still within the infrared information considered using the Wratten #88a filtration system.
This research validates the hypothesis that infrared picture taking can be used to visually recover underlying tattoo designs from cover tattoo designs done purposefully to obstruct the visualisation of said actual tattoo. The success of this technology is dependent on the colours used, namely if the tattoo is protected with dark-colored ink the infrared will not identify anything beneath it. That is an invaluable technique that may be used to identify individuals with a brief history of incarceration or gang affiliation that may experienced their identifiable sign deliberately covered.
Future prospects
Further research could be done to determine the structure of inks. This is a difficult job as manufacturers are not forced to disclose the ingredients of the inks.
Other future prospects include the probability of looking specifically at laser treated original tats underneath cover tattoos using infrared picture taking.
There are opportunities to further manipulate the images on Photoshop software. Included in these are pinpointing regions of extreme coloring changes, that is the areas of the records where the infrared visually takes out the colour, and finding the variations in the RGB principles to provide more data for statistical evaluation.
Appendix 1
