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Incorporating motion, edge, and focus detection

In order to determine the ROI for each frame of a movie, we need to be able to incorporate the results of motion, edge, and focus detection into a single system. The way we accomplish this is by analyzing each frame in five separate sections.

Frame region analysis

For motion and edge detection, the entire frame is processed at once, and then the resulting matrix is broken into 5 regions as below:

The 5 analysis regions for motion and edge detection

Scene from “Punch Drunk Love”

For motion detection , recall that the processing results in a “difference” matrix after subtracting two frames. The mean of the difference values is taken for each region and divided by the mean of the difference values for the whole frame. These region means are then normalized by the one with the largest magnitude. The result is a number between 0 and 1 for each region, with a value of 1 indicating the region of maximum relative change and 0 indicating no change.

For edge detection , recall that the processing results in an edge matrix, where a value of 1 means that that pixel is part of an edge and a value of zero indicates that the pixel is not part of an edge. Thus the sum of the pixels in each region is found and normalized to the region with the highest sum. The result is a value between 0 and 1 for each region, with 1 indicating the region with the most edges and 0 indicating a region with no edges.

For focus detection , recall that the processing results in a value for the slope of the linear regression of the loglog plot of the power spectrum. Due to the requirement of a square matrix for the 2D Fourier transform, the frame is divided into 5 semi-overlapped square regions:

The 5 analysis regions for focus detection

Scene from “Punch Drunk Love”

The focus detection processing is performed on each of these regions, and then the most in-focus region is identified (by its falloff rate), and the remaining regions are assigned a normalized value corresponding to how close they come to having the best focus value. The result is a value between 0 and 1 for each region, with 1 indicating the region of best focus and 0 indicating the region of worst focus.

Assigning the roi

After converting the results of motion, edge, and focus detection into values between 0 and 1 for each region, the values are averaged for each region. This gives one value for each region, with higher values indicating that there are more elements of interest in that region.

To translate this into an ROI, a horizontal midpoint is defined within the widescreen frame, and each region’s interest value is mapped to a weighted deviation from this midpoint. The net deviation from midpoint is then found by summing these deviations, and the fullscreen ROI midpoint is defined to be at this deviation from widescreen center.

Thus, interest in regions 1 and 2 act to pull the fullscreen ROI to the left, while interest in regions 4 and 5 acts to pull the fullscreen ROI to the right, and activity in region 3 acts to maintain the fullscreen ROI at the center.

The final midpoint value is filtered with a moving average (half-width = 30, or approximately 1 second of video) to eliminate jerky ROI movements.

Questions & Answers

what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
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Akash Reply
it is a goid question and i want to know the answer as well
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Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
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I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
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Victor Reply
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Smarajit Reply
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Source:  OpenStax, Adaptive region of interest for video. OpenStax CNX. Dec 14, 2010 Download for free at http://cnx.org/content/col11256/1.1
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