Friday, 1 April 2011
Step 1
Keying
when you take some pixels on the image
according to there chroma information or lumer information
and you make them invisible so that you can replace that information
with something else
the most comment use for keying is done with footage shoot on a green screen
especially used for the weather man who is shoot on a green screen then the weather map is then placed were the green screen pixels were.
When filming my footage i want to make sure that i lit the green screen well
as evenly lit as possible and if i am planning the track the background footage i will need to make sure that the white markers are visible within the footage.
Also it would help me later when it comes to keying if my green screen material is nice and pressed free from bumps and crushed parts.
want to place my green screen file into the project panel
either by importing or dragging it from the fie directly into the pane l
then create a composition with the file by dragging it into my composition area
I am now going to select the green screen pixels according to its chroma information. The reason green is used in keying is because green is one of the only colours that you shouldn't find in the human skin were as blue and red are common colours which are found in skin, so if one was to use these other colours selecting the background would be a murderous task.
KEYYING/KEYLIGHTING FOR GREENSCREEN
Keying
when you take some pixels on the image
according to there chroma information or lumer information
and you make them invisible so that you can replace that information
with something else
the most comment use for keying is done with footage shoot on a green screen
especially used for the weather man who is shoot on a green screen then the weather map is then placed were the green screen pixels were.
When filming my footage i want to make sure that i lit the green screen well
as evenly lit as possible and if i am planning the track the background footage i will need to make sure that the white markers are visible within the footage.
Also it would help me later when it comes to keying if my green screen material is nice and pressed free from bumps and crushed parts.
want to place my green screen file into the project panel
either by importing or dragging it from the fie directly into the pane l
then create a composition with the file by dragging it into my composition area
I am now going to select the green screen pixels according to its chroma information. The reason green is used in keying is because green is one of the only colours that you shouldn't find in the human skin were as blue and red are common colours which are found in skin, so if one was to use these other colours selecting the background would be a murderous task.
there are many ways in which you can edit this green screen footage but through research i have found that experts say that the easiest way is by using an effect called Keylight.
select the footage layer in the composition panel and then scroll up to your effects panel. Now click the word Keylight. You should now see a box open up on the left hand side of your workspace in your effects control panel.
Are next job is now that we want to tell keylight which colour in our footage that we would like to turn into transparency.
Now you want to go over to the word screen colour which is located within the effects control panel you have just open up. You now need to click the eyedropper tool which is located to the right of that word. Once you have clicked the tool you now want to click on the greenscreen background. The best areas to click which i have been told by two different sources and both work very well.
Is to 1) Click on the darkest shade of green or 2) to click on the green which is closest to the hair.
The reason you click the darkest spot is because when you have removed the green screen the darkest spots are hardest to remove. Clicking the darkest spot will allow the other lighter shades to be picked up a lot more easier.
Also the reason you want to select spots near the hair is because the hair is the hardest thing to keep after Keylighting.
Once you now click the green screen, the background will turn black.
You now want to click on the toggle transparency button located at the bottom of the composition panel, which should be under your greenscreen footage.
the background will now be transparent, you will see that this method is a lot more effective than other methods used to obtain the same result.
You will probably look at the screen and believe that you have got rid of all your green screen footage, but think again there maybe some traces of green left behind. So you now want to go back in and eliminate this by going back to your Keylight effects panel. Select the small box named Final Result now select the word screen matte.
The view will change to show you a grey scale representation of your footage. The white pixels will represent opacity, the black pixels will represent transparency and the greyscale pixels represent semi transparency.
you will see that the whites are not as white as they could be and the blacks are not as black as they could be. So im going to play around with Screen Gain and the Screen balance in the Keylight panel. I am just trying to clean up the pixels with this method. You basically want to do this until you see a cleaner pixel colour for both the white and black areas.
We use the despoil bias to make sure there is no more green in the footage.
Now you will need to go back into your view and change the Screen Matte back to Final Result. You should see the difference.
04:08 3. Keying & Keylight - Chapter 7 Basic Composting
when you take some pixels on the image
according to there chroma information or lumer information
and you make them invisible so that you can replace that information
with something else
the most comment use for keying is done with footage shoot on a green screen
especially used for the weather man who is shoot on a green screen then the weather map is then placed were the green screen pixels were.
When filming my footage i want to make sure that i lit the green screen well
as evenly lit as possible and if i am planning the track the background footage i will need to make sure that the white markers are visible within the footage.
Also it would help me later when it comes to keying if my green screen material is nice and pressed free from bumps and crushed parts.
want to place my green screen file into the project panel
either by importing or dragging it from the fie directly into the pane l
then create a composition with the file by dragging it into my composition area
I am now going to select the green screen pixels according to its chroma information. The reason green is used in keying is because green is one of the only colours that you shouldn't find in the human skin were as blue and red are common colours which are found in skin, so if one was to use these other colours selecting the background would be a murderous task.
there are many ways in which you can edit this green screen footage but through research i have found that experts say that the easiest way is by using an effect called Keylight.
select the footage layer in the composition panel and then scroll up to your effects panel. Now click the word Keylight. You should now see a box open up on the left hand side of your workspace in your effects control panel.
Are next job is now that we want to tell keylight which colour in our footage that we would like to turn into transparency.
Now you want to go over to the word screen colour which is located within the effects control panel you have just open up. You now need to click the eyedropper tool which is located to the right of that word. Once you have clicked the tool you now want to click on the greenscreen background. The best areas to click which i have been told by two different sources and both work very well.
Is to 1) Click on the darkest shade of green or 2) to click on the green which is closest to the hair.
The reason you click the darkest spot is because when you have removed the green screen the darkest spots are hardest to remove. Clicking the darkest spot will allow the other lighter shades to be picked up a lot more easier.
Also the reason you want to select spots near the hair is because the hair is the hardest thing to keep after Keylighting.
Once you now click the green screen, the background will turn black.
You now want to click on the toggle transparency button located at the bottom of the composition panel, which should be under your greenscreen footage.
the background will now be transparent, you will see that this method is a lot more effective than other methods used to obtain the same result.
You will probably look at the screen and believe that you have got rid of all your green screen footage, but think again there maybe some traces of green left behind. So you now want to go back in and eliminate this by going back to your Keylight effects panel. Select the small box named Final Result now select the word screen matte.
The view will change to show you a grey scale representation of your footage. The white pixels will represent opacity, the black pixels will represent transparency and the greyscale pixels represent semi transparency.
you will see that the whites are not as white as they could be and the blacks are not as black as they could be. So im going to play around with Screen Gain and the Screen balance in the Keylight panel. I am just trying to clean up the pixels with this method. You basically want to do this until you see a cleaner pixel colour for both the white and black areas.
We use the despoil bias to make sure there is no more green in the footage.
Now you will need to go back into your view and change the Screen Matte back to Final Result. You should see the difference.
04:08 3. Keying & Keylight - Chapter 7 Basic Composting
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