Chroma keying , 2 sense , with pics

fan-boy wrote on 2/17/2019, 9:03 PM

pics are numbered at the top "pic 1 of 4" etc.

wow ! doing it one way gives a Hard Cut ( pics 1 and 2 ) . Doing it the other way gives a gradient cut ( pics 3 and 4 )

seems the best screen is a screen that has a uniform lit color . The actual color of the screen is less important , assuming the surrounding environment colors are not the same as the screen's color .

I think the eye dropper can be dragged in a rectangle to get an averaged sample of colors .

question : some of the Game Capture devices say they can do Live chroma cut , to remove background room clutter . Aver-Media says they can do that withOUT a screen ! How is that possible ? Their website says so .

Comments

xberk wrote on 2/17/2019, 11:39 PM

>>seems the best screen is a screen that has a uniform lit color

Correct.

>>Aver-Media says they can do that withOUT a screen ! How is that possible ?

It's not without serious rotoscoping. They are saying you don't need the screen to be green. They say "...use which ever color screen or cloth you have available." .. Long before Green screens, there was blue screen.

Last changed by xberk on 2/17/2019, 11:40 PM, changed a total of 1 times.

Paul B .. PCI Express Video Card: EVGA VCX 10G-P5-3885-KL GeForce RTX 3080 XC3 ULTRA ,,  Intel Core i9-11900K Desktop Processor ,,  MSI Z590-A PRO Desktop Motherboard LGA-1200 ,, 64GB (2X32GB) XPG GAMMIX D45 DDR4 3200MHz 288-Pin SDRAM PC4-25600 Memory .. Seasonic Power Supply SSR-1000FX Focus Plus 1000W ,, Arctic Liquid Freezer II – 360MM .. Fractal Design case ,, Samsung Solid State Drive MZ-V8P1T0B/AM 980 PRO 1TB PCI Express 4 NVMe M.2 ,, Wundiws 10 .. Vegas Pro 19 Edit

fan-boy wrote on 2/18/2019, 3:24 PM

@xberk

at Aver Media web site , their sample video shows someone gaming in a room , from web cam I guess . No screen behind them , just "Room Clutter" , and they switch to "No clutter background" , as if by Magic . The person is still gaming in the room . did I miss-understand what they said ? I thought they meant Real Time Live cut . TV sports do a lot of overlay\underlays during live sports , I thought Aver Media was doing a Live real time cut for Live streaming , without the need for a screen .

After seeing the above Chroma Key results , was wondering if this will be an effective Top Down approach ?

While in Chroma Key is OFF , use the eye dropper to pick\find 2 extreme levels of green or blue screen pixels . Make note of those 2 RGB pixel values . then find or manually calculate a central RGB pixel value . Next turn Chroma Key ON , and set to cut just the Center RGB value ( as I did in the pics above ) , and adjust the other slider so it will extend the cut symmetrically , just enough to reach the 2 extremities of screen color . using either the Hard Cut extend or the Gradient cut extend . seems reasonable to try . Need a real image of an actual lit screen to test it on . No green\blue screen here .

cutting a single RGB value is not an issue anymore . Need to test this range cutting technique on a less then perfectly lit screen .

I re-read Vegas ? help , in Chroma Key dialogue . It does mention the word "Opaque" , but it doesn't talk about a symmetrical cut .

the underlying cause of all this is the help definitions of how to use the controls . Oh , just adjust it until it looks good .😵

xberk wrote on 2/18/2019, 4:11 PM

>> Oh , just adjust it until it looks good .😵

That's what I do.

>>No green\blue screen here .

Then you need to mask out the background. If you can find a way to use Chroma Key without a screen successfully, let us all know. Remember, all you need is a solid color background (green or blue is best) and a way to light it very evenly. I've used my 60" television for a green screen background by rendering out a 10 min video of just a green screen solid color and then playing the video back on my 60" TV. I put a small light on the talent in front of the TV and got my Green screen that way. A 5 x 7 green screen cloth can be bought for less than $15.

Paul B .. PCI Express Video Card: EVGA VCX 10G-P5-3885-KL GeForce RTX 3080 XC3 ULTRA ,,  Intel Core i9-11900K Desktop Processor ,,  MSI Z590-A PRO Desktop Motherboard LGA-1200 ,, 64GB (2X32GB) XPG GAMMIX D45 DDR4 3200MHz 288-Pin SDRAM PC4-25600 Memory .. Seasonic Power Supply SSR-1000FX Focus Plus 1000W ,, Arctic Liquid Freezer II – 360MM .. Fractal Design case ,, Samsung Solid State Drive MZ-V8P1T0B/AM 980 PRO 1TB PCI Express 4 NVMe M.2 ,, Wundiws 10 .. Vegas Pro 19 Edit

karma17 wrote on 2/22/2019, 6:08 AM

I believe you are correct about the eye dropper. Also, with all the scopes and charts and color wheels and everything, I remember someone once telling me that they use their eyes to assess the image and go by that. I thought it was funny because at the end of the day isn't that what we all do?

VEGASPascal wrote on 2/22/2019, 7:59 AM

>>Aver-Media says they can do that withOUT a screen ! How is that possible?

Background substraction. Take a picture of the screen without the person and subtract the live recording (like surveillance cameras are doing to detect a person).

Mask-person detection: with deep learning like Microsoft is doing.

In both cases the result is not precise.