Video Frame Averager,
Video Frame Grabber,
Video Noise Reduction     -     448 & 449 Series
Now Available for High-Definition!
Do you need video cables or adapters?
The Model 448S Video Frame Averager, Video Frame Grabber or Video Freeze Frame
creates a freeze frame picture image, upon request, representing the average of a selected number of
subsequent frames. This function is most commonly used to reduce dynamic noise, such as "snow", in a scene
where there is relatively little or no motion.
In its "live" mode, the input signal will pass to the output. When the Frame Averager is flipped to its
"average" mode and its "start" button is pressed, it will grab or capture a selected number of subsequent frames
or fields of video from the input and provide their average value at its output continually until it is given a
command to average a new series of frames. The number of frames is selectable in powers of 2 by a series of
four switches on the unit's front panel. In "Frame" Mode, resolution is 720H X 480V pixels at 29.97 frames per
second. In "Field" Mode, resolution is 720H x 240V pixels at 59.94 fields per second. Video inputs to the
Video Frame Averager from analog tape must be time base corrected.
The Colorado Video Model 449 Dynamic Video Noise Filter / Reduction System or
Video Noise Reducer can filter or reduce dynamic video noise (like "snow" or "static") out of a monochrome
video signal by essentially averaging frames over time. This type of video noise filtering or reduction is best
suited for signals with rapidly changing noise in pictures of relatively static (unchanging) subjects.
The Model 449 Dynamic Video Noise Reduction System provides a running quasi-average, or temporal filtering,
of the video signal at its input. More precisely, the value for any given pixel in the units output is
determined by the equation:
where Pn is the value of the pixel in the current output frame, Pi is the value of the pixel in the current
input frame, Pn-1 is the value of the pixel in the previous output frame, and t is a user selected time constant.
This equation is solved for each pixel at the normal video frame rate of 30 times per second. As the user
selects larger values for t, the exponentially decaying influence of a given pixels value in a particular input
frame will persist over a longer period of time in subsequent output frames. The Model 449 allows values of t
to range from zero (binary 0000) to 15 (binary 1111), making possible temporal filtering of from one to 32,768
(in steps of powers of two) frames on a running basis. The Model 449s 16-bit grayscale resolution provides
65,536 shades of gray for the filtering process.