The usual aim of enhancement and restoration services is to improve visual or sonic clarity or to repair damage. Forensics applies those services on audio visual media with regard to legal matters.
We have performed a number of forensic operations where the result is not something we can share publicly but they have involved things like removing noise to make voices understandable, creating animations from still photos, making surveillance footage more clear or enlarging areas of interest in a photo or video for improved detail. We have also provided written professional analysis.
Original motion picture film often has an impressive latitude for adjustment and improvement even when the film appears to be very dark or washed out when viewed on a projector. In some cases, decent viewable images can be produced where there doesn’t appear to be much if anything on the film.
Restoring color balance often improves more than just color accuracy. Image clarity and more distinct detail often result from correcting color errors or biasing made during the recording of video or still images. Because image details are not stored equally across the primary colors—restoring color balance can bring out details that are otherwise muddled by incorrect color reproduction.
This silver-halide photo (not inkjet) print survived a fire but had heat staining in addition to actual melting of the print emulsion. Facial details, subtle shading in the horse’s flank and faint details in the distant background were all retained in the scanning process. The staining was completely removed and the print returned to pre-fire condition with a full range of tonality.
Audio, Film, and Video Enhancement
Removing Audio Squeal
An audio history recording had a piercing audio squeal making it uncomfortable to listen to. The squeal is almost completely removed with custom filtering that makes the participants voices more understandable.
Bear in mind: the following video examples that come from VHS originals will look good on a phone or tablet screen but will appear much lower quality on a desktop computer display—especially in full-screen mode. Set computer viewing to “actual size” to see the samples in the resolution they originated in. Similarly, with audio enhancements, improvements will be much more noticeable on a computer or home entertainment sound system versus the tiny speakers of a phone or tablet.
This film capture only existed on VHS videotape, there was no original film to go back to and the film to video transfer was marginal quality with, in some cases, imagery being washed out and almost gone completely. The objective was to make the skater’s skillful movements viewable again and leave it at that. Uneven illumination of the image and other correctable defects were intentionally left alone to conserve budget.
The standard hum filter (either 50Hz or 60Hz) made almost no difference in correcting the audio noise in this 80’s era VHS tape from the PAL European television standard. There was also a significant buzzing throughout. Custom audio filtering was employed to make the conversation between mother and baby audible. Significantly lowering the noise level also allowed boosting the conversation so that subtle sounds that had been covered by noise are now audible.
The sound of loud rain masks clarity of a presenter’s voice during this conference. Custom filtering significantly lowers the sound of the rain allowing the speaker to be heard more clearly.
Improving sound quality was the main goal. This VHS recording of a high school marching band has thin sounding audio from the limited audio range of VHS tape. Dynamics and other audio processing brings back the punch. The video was sharpened and adjusted for contrast and color balance. In examples #1 and #2 there was much more audio improvement possible than picture. Example #3 had more picture improvement possible than audio.