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Just as we have a variety of HD formats and a variety of HD file sizes,
we also have a variety of HD image sizes. This is a standard television that we watch
every night, standard definition NTSC 720x480. Well actually, not quite true.
Standard broadcast television is 720x486. The image size that we put onto an NTSC DVD
is 720x480 and if we're dealing with PAL, it's 720x576.
But for the purpose of this comparison, we'll work with NTSC at 720x480.
By a comparison here is one HD size. This is HD 1280x720.
When we're talking with HD, we're talking the last number, the vertical resolution.
720 means that it's 1280 pixels across by 720 pixels high, and we call that the 720
format. The next HD size is a little bit bigger. It's
1920 pixels across and 1080 pixels high, called 1080.
So 720 HD is the middle box, 1080 HD is the larger box.
The advantage to 720 is the file sizes are smaller.
The advantage to 1080 is the pictures are bigger,
but HD doesn't stop here. We have another size, which is commonly used
for film intermediates called 2K. 2048 pixels across by somewhere around 1556
pixels high. Cropping can change the vertical dimension.
We call this the 2K image and you may have for about the red camera
which everybody is excited about. The red camera gives us 4000 pixels across
by 2304 pixels high, when it's shooting in a 16x9 mode.
As you can imagine, as your image sizes increase, render times also increase because there's
more pixels that have to be rendered. So another thing that you have to keep in
mind as you're working with HD is if you're doing a lot of effects work,
you need to budget the time for rendering of your effects because a 1080 image is going
to take six to eight times longer to render. Just because there's that many more pixels.
But it's not just the image size which is contributing to all the confusion with HD.
We also have different scanning formats. We'll talk about those next.