forensic-photography

FORENSIC PHOTOGRAPHY

Chapter 1: Definition of Terms Photography

Literal Definition:

• The term "photography" is derived from Greek roots:

  • PHOS: means "light"

  • GRAPHIA: means "write"

• Together, they translate to "write with light", reflecting the essence of how photographs are created through light exposure.

Modern Definition:

• Photography is defined as an art or science that studies images formed by light acting upon sensitized materials. Essentially, it involves capturing and manipulating light to create visual representations.

Technical/Legal Definition:

• In a technical and legal context, photography encompasses every method used to record images. This includes:

  • Chemical means: Such as traditional film photography where light-sensitive chemicals react to light.

  • Thermal means: Utilized in infrared photography where heat emissions are captured.

  • Electrical or electronic means: Pertaining to digital photography where sensors convert light into electronic signals.

Police Photography:

• This is the study of photography principles and the preparation of photographic evidence specifically for law enforcement purposes, crucial for documentation and investigation.

Forensic Photography:

• Defined as the art or science of documenting crime scenes and evidence for laboratory analysis and court trials, which requires precision and adherence to legal standards.

A. Basic Components of Photography

Light:

• Light is integral to the photographic process; it is the fundamental element deemed "good" in the context of creation and artistic expression.

Equipment:

• The portable Camera Obscura was historically used by artists to achieve accurate perspective in drawings, laying the groundwork for future photographic technologies.

Chemicals:

• The discovery of light sensitivity in substances like silver nitrate and silver chloride led to early photographic processes, notably by pioneers such as Thomas Wedgewood and Humphrey Davy, who were able to produce Photograms by exposing these chemicals to light.

Historical Evolution of Forensic Photography

True Photography (1839):

• This year marks the birth of photography, highlighted by the introduction of Talbot's calotype, which employed light-sensitive paper for producing images. Additionally, Daguerre's daguerreotype demonstrated the capability of direct image formation on polished silver metal plates, revolutionizing image capture.

Further Innovations (1848-1889):

• Abel Niepce de Saint-Victor: Innovated negatives on glass using albumen.

• Blanquart-Evard: Developed printing paper treated with albumen for better image quality.

• Archer: Introduced the wet plate process with collodion, allowing for clearer and more detailed images.

• 1885: Commercial introduction of gelatin emulsion printing paper, allowing for sharper images and easier handling.

Key Contributions (1856-1907):

• 1856: Hershel coined the term "photography", greatly influencing its recognition.

• 1861: Maxwell’s groundbreaking research on color theories expanded the photographic spectrum.

• 1906: Introduction of color-corrected plates enhanced photographic accuracy.

• 1907: The Lumiere color process was launched, utilizing filters for color photography.

• 1914: Kodak's introduction of the Kadachrome color process made color photography more accessible.

• 1947: Land's advancement in photography technology with "Polaroid" provided instant image development.

Digital Age (1988-1999):

• Laser technology introduced holography in the 1960s, expanding the field of photography.

• The emergence of digital cameras started in earnest with the Fuji DS-1P, followed by commercial units like the Kodak DCS-100.

• The Casio QV-10 innovated by adding an LCD monitor to consumer cameras, changing how photographers viewed images.

• The Nikon D1 became the first widely recognized digital SLR, solidifying digital photography's place in the field.

Criminal Applications

Historical Use:

• 1854: The introduction of dry plate photography by Maddox was utilized for prison records, marking a shift in criminal documentation.

• 1859: Forensic photography was first used in a California forgery case, showing its importance in legal frameworks.

• 1864: Odelbercht's advocacy for photography in crime scene documentation further standardized photographic evidence practices.

Rogues Gallery:

• This includes comprehensive photographic documentation of suspects, featuring full-face, body shots, and profiles, enhancing law enforcement archives.

• 1882: Bertillon's anthropometric measurements were complemented by photographic documentation, creating a more systematic approach to identifying suspects.

Advancements in Forensic Science:

• 1902: Dr. Reis established one of the earliest crime labs, integrating forensic photography into criminal investigations.

• 1910: Baltazard’s development of photographic comparison methods was foundational to forensic ballistics, establishing protocols for evidence examination.

Criminology Education:

• 1902: Dr. Reis set up one of the first forensic science academic curricula, professionalizing the field.

• 1950: Vallmer laid the groundwork for criminology education by founding the School of Criminology at UC, fostering future generations of forensic scientists.

• 1954: The establishment of the Philippine College of Criminology further spreads the discipline internationally.

Chapter 2: Photographic Rays - Its Nature and Characteristics

Nature and Speed of Light:

• Light is a form of radiant electromagnetic energy traveling in wave motion at approximately 186,000 miles per second. Understanding its properties is crucial for photographers.

• Wavelength: The distance from crest to crest of a light wave, influencing its behavior and appearance.

• Frequency: The number of waves that pass a given point per second, affecting the energy and color of light.

Four Photographic Rays of Modern Photography:

• X-rays: Wavelength of 1 to 30 nanometers, useful for medical and security imaging.

• Ultraviolet Rays: Wavelength of 30 to 400 nanometers, often used in forensic analysis to reveal hidden details.

• Visible Light: Wavelength of 400 to 700 nanometers, the spectrum observable by the human eye, essential for traditional photography.

• Infrared Rays: Wavelength of 700 to 1000+ nanometers, utilized in capturing images under low-light conditions or for thermal imaging.

Luminescence:

• The conversion of radiant energy to another wavelength, which is essential in various photographic processes.

  • Fluorescence: Objects transform wavelength while irradiated, generating visible light.

  • Phosphorescence: After the energy source is removed, objects continue to emit a new wavelength, exhibiting persistence in glow.

Production of Colors:

• Absorption: Variation in light absorption leads to the perception of colors, pivotal in color photography.

• Scattering: Atmospheric effects, such as Rayleigh scattering, produce colors, notably the blue sky.

• Interference: Light waves interacting produce colors in thin films, as seen in soap bubbles and oil slicks.

• Dispersion: Refraction differences experienced by light create rainbow effects, a spectacle of spectral colors.

Light Bending:

• Reflection: The bouncing back of light from surfaces, crucial for image formation.

  • Regular Reflection: Occurs on smooth surfaces, maintaining clarity and detail.

  • Irregular/Diffused Reflection: Happens on rough surfaces, scattering light in various directions.

• Refraction: Bending of light between different mediums, essential in lens design for photography.

• Diffraction: Bending of light around edges of opaque objects, contributing to image resolution and quality.

Object Classification by Light Behavior:

• Transparent Objects: Clear visibility of objects behind them, crucial for certain photographic effects.

• Translucent Objects: Permit light but diffuse it, useful in achieving soft lighting.

• Opaque Objects: Block light completely, resulting in indistinguishable backgrounds in imagery.

Sources of Light:

• Natural Light: Includes sunlight, moonlight, and varies in intensity and quality under different atmospheric conditions.

• Artificial Light: Man-made sources such as incandescent, fluorescent, and LED lights, critical for indoor and low-light photography.

Forensic Light Sources:

• Ultraviolet Lamp: Portable units used in forensic work to detect hidden bodily fluids and other substances.

• Laser: Effective for detecting biological stains that might be invisible under normal light conditions.

• Alternative Light Source: Features high intensity, non-coherent light with specific filters to enhance visibility of particular evidence.

• Forensic Light Source: Cost-effective light sources employing filtered white light for crime scene examination and analysis.