“Stop… Right there… Zoom, enhance!”
We’ve all seen this happen on TV – a suspect is caught on a grainy security camera, but the skilled technicians of the crime lab are able to enhance his face to identify him. Or maybe they zoom into an image in order to read a license plate. It all sounds easy – it’s often no more than a few key strokes away!
Unfortunately, in the real world, enhancing video isn’t nearly as easy. There are a number of factors that affect the ability of video analysts to “enhance”, or improve, the quality of a piece of footage.
What is video?
At its heart, a video file is little more than a series of images. Each frame is one image, and frames are played back at a rate determined by the recording device. Every image is made up of pixels. A pixel, for our purposes, is best defined thusly: A square block of solid color information. That means a pixel can only ever be a single color – there is no further information below it, no way to turn one pixel into more, smaller pixels.
This means that the amount of information stored in an image is limited by the pixel resolution. Here’s an example: You have security footage of a car that stops in front of a business. You want to know the license plate number from the car, but the license plate is only a white block made of a handful of pixels. In this scenario, no amount of enhancement would make the plate number legible – increasing the resolution of the video would only increase the size of the white area. This is because video enhancement can only work with the information available in an image, and should never be used to attempt to create additional pixel information.
A similar situation can occur when a camera records pixels with extremely high or low brightness values. Video is typically recorded in 8 bit color spaces – meaning there are 256 possible values each for red, green, and blue in a single pixel. While that produces a tremendous range of color, it is limited – a pixel that is recorded as 0,0,0 (black) will always be black; there’s no further information to pull out. If part of the image sensor is blown out with light, the pixels will be solid white with no additional details.
At the end of the day, one must remember video will only ever be as good as what was recorded. The quality of a video is dependent not just on what the camera could see, but also how it was able to record what it saw. Because video files are so large, they are also often compressed – this can often cause further degradation of the available information.
Can my video be enhanced?
This may make it sound like video enhancement is a thing of fantasy – nothing could be further from the truth. However, one must take stock of the quality of the video you’re starting from, and also be realistic about what you want to achieve. Even with a low quality video, a dedicated video analyst can still find and interpret information that is useful to a case. Often, “enhancement” isn’t necessary for the work these analysts do.
When used as a demonstrative, video can still greatly benefit from enhancement. The resolution can still be scaled up – while this won’t add more detail, it can make playback easier to view. Contrast can be increased and brightness levels adjusted, to bring out details without making substantial alterations to the content. The biggest enhancement might not be considered enhancement at all: using still frames taken from video, analysts can annotate, highlight, and otherwise walk an audience through the information that was recorded in the video. This interpretation and presentation is essential for ensuring the audience takes away the correct facts from a video.
What are my options?
For both investigations and presentations, there is almost always something that can be done to “enhance” a video – just be sure to manage your expectations. Often the biggest enhancement you can provide is context – highlighting important details in a video, explaining what it does show, and directing the audience to the correct conclusions.
If you’re unsure of what you have, the easiest course of action may be to have a dedicated video analyst take a look at it. Often video evidence can be quickly triaged, and the analyst will be able to explain what best course of action will be.
If you have a case with video evidence, contact ARCCA today to see how we can assist you.