IAI CFPH key terms

The branch of imaging used to document evidence, scenes, injuries, and persons for legal proceedings. It aims for accurate, unbiased, reproducible records rather than artistic effect, and follows documented, consistent procedures so results can withstand scrutiny in court.

Imaging of specific objects or marks collected or documented as evidence, often under controlled lighting with a scale. The goal is a faithful record of shape, color, texture, and size, plus sufficient detail for comparison or later analysis by another examiner.

Systematic imaging of a scene before and after evidence collection, using overview, mid-range, and close-up views. The sequence preserves context and spatial relationships, and must be completed before items are moved or altered wherever practical and safe.

A wide view showing the entire scene and its surroundings, establishing where things are relative to rooms, entrances, and landmarks. It is normally taken first, before any disturbance, and often from multiple corners to show the full layout.

A view that shows an item of evidence together with its immediate surroundings, bridging the overall and close-up views. It helps a viewer understand what the object is near and how it relates to other items, furniture, or surfaces.

A detailed image of a single item, mark, or injury, typically with a scale for size and sometimes with an evidence label. It is usually taken in a three-step set: a mid-range view, the close-up with scale, then the same view without scale.

A ruler or marker of known length placed beside an item so dimensions can be judged or measured from the image. It should sit in the same plane as the subject and be visible in the frame without obscuring features of evidentiary value.

A standardized L-shaped reference scale with millimeter graduations and color patches, used mainly for bite marks and injuries. The L shape lets the examiner align the scale and later correct for perspective, and the colors help assess color balance in the image.

A card or board placed in the frame showing identifiers such as case number, date, item number, or photographer. It links the image to a specific item and case, and must be positioned so it does not hide or alter the evidence being documented.

A written record listing each image or exposure with its number, subject, location, lighting, scale used, and photographer. It supports later explanation of the image set and helps demonstrate that the documentation was systematic, complete, and traceable to the case file.

The documented, unbroken record of who handled an item or image file, when, and for what purpose. For digital images this includes original cards, hashes, and copies, so a court can see that the material was not altered or substituted.

A fixed-length digital fingerprint computed from a file's contents, used to show that the file has not changed. If a single bit changes, the hash changes, so matching hashes before and after copying support claims of integrity.

A hardware or software tool that prevents a computer from writing to a storage device while it is being read. It protects original media such as camera cards from accidental alteration during imaging and copying of digital evidence.

The original format in which a camera or device saved an image, such as a manufacturer raw file or the camera's JPEG. Preserving the native file, rather than only a converted copy, keeps the original data available for re-examination and verification.

A camera file holding minimally processed sensor data rather than a finished image. It retains more tonal and color information for later adjustment, but requires specific software and is not a universal standard, so conversion must be documented.

Data stored within an image file describing capture details such as date and time, camera model, lens, exposure settings, and sometimes location. It can support or challenge accounts of when and how an image was made, so it should be preserved and examined.

The change in apparent size and shape caused by camera angle and distance, so nearer parts look larger and parallel lines may converge. It can make injuries or marks look wrong in size or shape, so the camera should be kept square to the subject.

Deriving measurements or three-dimensional models from photographs, using known references, camera positions, or multiple overlapping views. In forensic work it can map a scene or estimate dimensions, but its accuracy depends on careful calibration and documented methods.

Using a laser scanner to record millions of points on surfaces, producing a measurable three-dimensional model of a scene. It preserves spatial relationships for later analysis and measurement, but needs documented registration and validation to be defensible.

The range of distance in front of and behind the focused point that appears acceptably sharp. It grows with smaller apertures and shorter focal lengths, and matters when a close-up must keep both an injury and its scale in focus.

The adjustable opening in a lens that controls how much light reaches the sensor, expressed as an f-number. Smaller openings increase depth of field but reduce light, so exposure must be balanced with shutter speed or lighting.

The total amount of light reaching the sensor, set by aperture, shutter speed, and sensitivity, together with any added lighting. Correct exposure keeps detail in both highlights and shadows so evidence is not hidden by clipping or darkness.

A graph showing how many pixels fall at each brightness level in an image. It helps the photographer judge whether shadows or highlights are lost, which is useful when reviewing an image on a small camera screen in poor light.

Adjusting an image so that neutral objects appear neutral under the actual lighting, compensating for tungsten, fluorescent, or daylight sources. Accurate color matters when comparing paint, fibers, or injuries, so a reference target or gray card is often included.

A card with known color patches and a neutral gray area, photographed with the subject to allow later correction and verification of color. It gives a documented standard against which the colors in the image can be checked.

A light source other than normal white light, such as ultraviolet, infrared, or a filtered forensic lamp, used to reveal substances or marks not visible under ordinary lighting. Filters on the camera and light are chosen to isolate the desired response.

Light emitted by a substance after it absorbs light of a shorter wavelength, appearing at a longer wavelength. Many biological fluids and treated fibers fluoresce under ultraviolet or blue light, which can reveal stains that are otherwise invisible.

A filter placed over the camera lens that blocks the excitation light and passes only the emitted fluorescence or reflected wavelength. Choosing the right barrier filter prevents the illuminating light from washing out the weak signal being recorded.

Imaging using near-infrared light, which can pass through some surface layers and reveal writing, gunshot residue patterns, or altered documents. A camera modified for infrared and an appropriate filter are needed, and results must be interpreted with care.

Photographing questioned documents to record writing, inks, indentations, and alterations under controlled lighting. Techniques include raking light, transmitted light, and infrared or ultraviolet imaging, each chosen to reveal specific features without damaging the document.

Light directed at a very shallow angle across a surface so that texture, indentations, or dust patterns cast small shadows. It is used for latent impressions, tool marks, and shoe or tire impressions on surfaces where flat lighting would hide detail.

Lighting from one side rather than straight on, used to create shadow and show surface relief. It helps record scratches, tool marks, and embossed or indented features, but the light angle must be recorded and kept consistent for comparison.

Recording footwear, tire, tool, or other impressions so that size, pattern, and fine detail can be compared later. The camera is kept square to the impression, a scale is included, and lighting is angled to reveal detail without distortion.

Photography at magnifications roughly from life size to about ten times, used for fingerprints, tool marks, fibers, and other small evidence. It requires stable support, careful lighting, and a scale, and often uses specialized lenses or bellows.

Photography through a microscope to record magnified detail of trace evidence such as hairs, fibers, or crystals. It documents what was observed at a stated magnification, and the microscope settings and scale must be recorded for later interpretation.

Combining several images taken at different focus distances into one image that is sharp throughout. It is useful in close-up work where depth of field is very shallow, but the combined image is a processed product and the original frames should be retained.

A method of recovering dry footwear or dust impressions from surfaces using a charged film that attracts particles. The lifted impression is then photographed or scanned, and the lift and its images are documented as part of the evidence record.

Documenting very small items such as hairs, fibers, glass fragments, or paint chips, often with a scale and magnification reference. The images support identification and comparison, and the item itself must be preserved and tracked through the chain of custody.