Forensic Photography: An Introduction

Forensic Photography Defined

• Photography is derived from the greek words PHOS meaning “light” and GRAPHIA meaning write
• Photography translates to "write with light"
• Photography is an art or science that studies images through light action on sensitized materials
• Technically, photography can be any means of recording images from chemical, thermal, electrical or electronic methods
• These methods use radiant energy, including gamma rays, X-rays, ultraviolet, and visible light rays
• Police photography uses photography principles to prepare photographic evidence for police work
• Forensic photography is photographically documenting crime scenes and evidence for lab analysis toward use in court trials

History of Forensic Photography

• Light is a basic component of photography, as referenced in creation stories
• Camera Obscura (dark chamber) was used by artists to get perspective and scale
• Light sensitivity of silver nitrate and chloride was discovered and investigated
• Thomas Wadgewood and Humphey Davy produce Photograms. in 1800

True Photography Origins

• 1839 is considered the birth year of photography
• William Henry Fox Talbot invented Calotype, using paper with light-sensitive compound at the Royal Society of London
• Louis Jacques Mande Daguerre and Joseph Nicephore Niepce collaborted to publically demonstrate a Daguerreotype in Paris
• Daguerreotype images formed directly on silver metal
• Talbot's calotype fixation was partial, compared to the permanent images made with hypo in Daguerreotypes

Early Advances

• 1848: Abel Niepce de Saint-Victor introduced negatives on glass using albumen as binding agent
• 1850: Louis Desirie Blanquart-Evard introduced albumen-coated printing paper for a glossy finish
• 1851: Frederick Scott Archer published a "wet plate" process using collodion instead of albumen
• Collodion is a viscous liquid that dries into a tough, flexible, transparent film
• 1885: Gelatin emulsion printing paper was commercially introduced, leading to film in 1889

Further Developments

• 1856: Sir John F.W. Hershel coined "PHOTOGRAPHY"
• 1861: James Clack Maxwell researched colors
• 1890: Full-corrected lenses were introduced
• 1906: A photographic plate was placed on the market that could reproduced all colors in equivalent shades of gray
• 1907: The Lummiere color process used a panchromatic film with blue, green, and red filters
• 1914: U.S. Eastman Kodak created a color subtractive process called Kadachrome
• 1935: Color processes and electronic flash developed together
• 1947: Edwin H. Land introduced "Polaroid," for one-step photography
• 1960: LASER was invented, enabling holograms (3D pictures)

Digital Era

• 1988: True digital cameras appear
• The Fuji DS-1P of 1988 was the first true digital camera and recorded images as a computerized file
• 1992: The Kodak DCS-100 was the first commercially available digital camera
• 1995: The Casio QV-10 was the first consumer digital camera with a Liquid Crystal Display (LCD) on the back
• 1996: The Kodak DC-25 was the first camera to use compact flash
• 1999: The Nikon D1 was the first digital SLR camera
• 2003: Canon introduced the 300D camera, also known as the Digital Rebel

Criminal Applications of Photography

• 1854: An Englishman named Maddox developed dry plate photography, making photography of inmates for prison records practical
• 1859: The first time forensic science was applied was in a California forgery case
• 1864: Odelbercht advocated using photography for identifying criminals, documenting evidence, and crime scenes
• Rouges gallery is a full face, full body shot and profile of the suspect.
• 1882: Alphonse Bertillion, who initiated anthropometric measurements for personal identification, also used photography for documentation

Forensic Science Pioneers

• 1902: Dr. R.A. Reis, a German scientist trained in Chemistry and Physics, used photography in forensic science and established the world's earliest crime laboratory
• 1910: Victor Baltazard developed a method to photographically compare bullets and cartridge cases, forming the foundation for ballistics

Criminology Education

• 1902: Dr. R.A. Reis set up one of the first academic curricula in forensic science
• 1950: August Vallmer established the School of Criminology at the University of California
• 1954: Plaridel Educational Institution in the Philippines pioneered criminology education and is now the Philippine College of Criminology

Photographic Rays

• Light is a form of electromagnetic energy that travels in waves at about 186,000 miles per second in air
• There are differences in wavelength and frequency
• Wavelength is the distance from crest to crest of a wave
• Frequency is the number of waves passing a point in one second
• Light is radiant electromagnetic energy visible to the naked eye
• X-rays have wavelengths of 1 to 30 nanometers
• Ultraviolet rays have wavelengths of 30 to 400 nanometers
• Visible light has wavelengths of 400 to 700 nanometers
• Infrared rays have wavelengths of 700 to 1000+ nanometers

Luminescence

• Luminescence is when a radiant energy converts to another wavelength
• Fluorescence is the ability of an object to convert one wavelength to another as long as energy is applied
• Phosphorescence is when an object continues to reflect the new wavelength after the energy source is removed

Primary Colors

• The three primary colors are red, yellow, and blue

Color Production

• Absorption: The color of ordinary objects comes the amount of light that they absorb
• Scattering: The color of the blue sky results from scattering of light by the atmosphere
• Interference: Colors result from light waves in thin films, like soap bubbles or oil films in water
• Fluorescence: Molecules of fluorescent material absorb energy at one wavelength
• Dispersion: Differences in refractive power of a transparent medium on light of different wavelengths, like a rainbow

Bending of Light

• Reflection is light is deflected or bouncing back of light when it hits a surface
• When light hits a flat, smooth, and shiny surface then regular reflection is caused
• When light hits a rough or uneven glossy object then irregular or diffused reflection is caused
• Refraction is the bending of light when passing from one medium to another
• Diffraction is the bending of light when it hits a sharp edge of an opaque object

Object Behaviors to Light

• Transparent objects allow sufficient visible light to pass through, making objects on the other side clearly visible
• Translucent objects allow light to pass, but diffuse it enough that objects on the other side are not well distinguished
• Opaque objects diffuse light so much that it is difficult or impossible to recognize objects on the other side

Light Sources

• Natural light sources includes sun, moon, lightning, fire, and other heavenly bodies
• Bright sunlight is a lighting condition where objects in open space cast a deep and uniform shadow
• Hazy sunlight is when objects cast a transparent shadow
• Dull sunlight means an objects in open space cast no shadow
• Cloudy bright condition in open space cast no shadow but objects at far distance are clearly visible
• Cloudy dull condition in open space cast no shadow and visibility of distant objects are already limited
• Artificial light: Man made
• Continuous radiation gives illumination continuously
• Short duration flash units give a brief light from burning metallic wires

Forensic Light Sources

• Ultraviolet lamps are used in forensic work in a variety of shapes, sizes, and powers and are portable for field work
• LASER stands for Light Amplification through Simulated Emission of Radiation and illuminates certain items
• It detects dried biological stains like seamen, urine or saliva
• Alternative light source provides a high intensity beam of non-coherent light through band pass filters
• Forensic light source applies filtered white light from a variety of sources