— Stelfie the Time Traveller (@StelfieTT) July 7, 2024
With LivePortrait you can just perform what you want the character on the screen to do. This clip is using cc0 footage from Pexels, but you can do this with all the AnimateDiff / Gen3 / Luma / Pika etc clips you've already made as well! pic.twitter.com/y2fLoC5183
To measure the contrast ratio you will need a light meter. The process starts with you measuring the main source of light, or the key light.
Get a reading from the brightest area on the face of your subject. Then, measure the area lit by the secondary light, or fill light. To make sense of what you have just measured you have to understand that the information you have just gathered is in F-stops, a measure of light. With each additional F-stop, for example going one stop from f/1.4 to f/2.0, you create a doubling of light. The reverse is also true; moving one stop from f/8.0 to f/5.6 results in a halving of the light.
Shutter is the device that controls the amount of light through a lens. Basically in general it controls the amount of time a film is exposed. Shutter speed is how long this device is open for, which also defines motion blur… the longer it stays open the blurrier the image captured. The number refers to the amount of light actually allowed through.
As a reference, shooting at 24fps, at 180 shutter angle or 1/48th of shutter speed (0.0208 exposure time) will produce motion blur which is similar to what we perceive at naked eye
Talked of as in (shutter) angles, for historical reasons, as the original exposure mechanism was controlled through a pie shaped mirror in front of the lens.
A shutter of 180 degrees is blocking/allowing light for half circle. (half blocked, half open). 270 degrees is one quarter pie shaped, which would allow for a higher exposure time (3 quarter pie open, vs one quarter closed) 90 degrees is three quarter pie shaped, which would allow for a lower exposure (one quarter open, three quarters closed)
