eli5 what is bit depth in film?
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How many colors are recorded.
Standard is 8-bit, 2^8 = 256 colors per red/green/blue pixel; 256^3 = 16,777,216 total colors (well, usually not all 256 colors per pixel are used, tv is 16-235 instead of 0-255 I think). This is why a bunch of color changing LEDs say >16M colors, because they are 8-bit color.
10-bit is next, that gives >1B colors.
12-bit is the current max I think, giving >67B colors.
This means there are more in-between shades. An extreme example would be that 2 colors for red would be off and full red, 3 colors would add pink.
This image explains it well imo;
http://4.bp.blogspot.com/-jLlRGBHYzm4/UN18PluygVI/AAAAAAAAAcI/zSy1XyieAcc/s1600/14+Bit+Depth+03.jpg
Essentially one bit gives two possible states; on and off, or black and white. If you have two bits you have four possible states (both on, both off, first bit on and second bit off, or first off and second on) so you can have black, white and two shades of grey in between.
The more bits the smoother the gradient you can achieve.
Your eyes have receptors for three colours: red, green and blue (and they are not very good at separating them, but that’s another issue). So in order to show you any colour, your screen simply has to mix these three colours in any combination to trigger these receptors, and you get to see any colour.
Because of the way computers work, the easy and usually “good enough” way to represent these colours was in three numbers that each take up 8 bits (=1 byte , which is just how most computers organize data internally). With 8 bits you can represent 256 different variations of each shade, and with three of them, that adds up (or rather: multiplies) to some 16 Million different shades of colours. More than enough for most situations, one might say.
However, there are situations where this is a bit too little: think of an evening sky, which gradually changes from one shade of blue to another over a larger area. What can happen here is that there are just not enough colour variations available and you get “bands” of the same colour when you see this on the screen.
One workaround is to “dighter” the colours, i.e. add a bit of noise, so the bands don’t become so apparent, but the better solution is to just double or even quadruple the number of colours by using 9 or even 10 bits per colour instead of 8.
This gives especially photography a lot more “room” in the colour space, and there will be much smoother gradients – or even greater details between very bright and very dark parts of the image, etc. It has the disadvantage that now the pictures need a lot more memory or bandwidth to store or stream.
Today, not all equipment (screens, graphic adapters, etc.) are fully able to handle these higher bandwidths, or to display the images – and honestly, just for watching some clips on YouTube it is normally not really relevant anyways – even less so for typical office work. Where it becomes interesting is either if you are an image artist and you are working on photography – or for watching movies. Well, maybe games look better, too 😉
its the number of bits used to represent a colour on each pixel. the higher the bit depth the more combinations/shades of red, green, and blue that can be represented. for example, x bits can represent 2^x shades. this is why black and white images are usually lower in file size compared to the same image with colours; they usually use 1 bit per pixel.
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