Glossary
Pixel- A pixel or
pel, is the smallest controllable element of a picture presented on the screen,
the placement of a pixel corresponds to is physical coordinates. Each screen is
divided into a matrix of thousands, or maybe even millions of pixels. Each
individual pixel can only be on colour each, but since pixels are so small they
often blend together to form different shades and blends of different colours.
Resolution-
Resolution refers to the clarity and sharpness of an image, this term is
often used to describe monitors, printers and bit-mapped graphic images. The more
pixels there are in an image, the more detail that image can be displayed with.
The fewer pixels there are within the image, the less detail there will be.
Bitmap images are composed of pixels, the images resolution is simply the
number of Pixels Per Inch (PPI) in
the bitmap grid. There are two main aspects to every bitmap image – its size
(width and height) and resolution (numb er of pixels per inch).
Screen
ratios- The aspect ratio of a screen or image describes the
proportional relationship between its width and its height. It is usually shown
as two numbers that are separated by a colon, for example 16:9 and 4:3. For an
x:y aspect ratio, no matter the size of the image, if he width is divided into
x units of equal length and the height is measured using the same length unit,
the height will be measured to be y units. The most common ratio used today in
the presentation of films in cinemas are 1.85:1 and 2.39:1. Two common video
aspect ratios are 4:3 (1.22:1), which is the universal format of the 20th
century. And finally 16:9 (1.77:1) which is universally known for
high-definition and European digital television. In still camera photography,
the most common aspect ratios are 4:3, 3:2, and more recently being found in
consumer cameras 16:9.
Frame rate-
The human eye and its brain interface, known as the human visual system
can process 10 to 12 separate images per seconds, perceiving each of them
individually. Early silent films had a frame rate ranging from 14 to 24 FPS
(frames per second) which created the sense of motion, however was perceived as
a jerky motion. Frame rate tells us exactly how many frames per second there
are when recording or playing video. A few examples are, Video cameras in
Europe use 25 frames per second (fps). In USA & Japan 29.97fps or 30fps is
used. And also, Animators often work with a lower frame rate (e.g. 12fps) so
less frames are needed for the same length video clip. Frame rate (also known as
frame frequency) is the frequency (rate) at which an imaging device produces
unique consecutive images called frames. The term applies equally well to film
and video cameras, computer graphics, and motion capture systems. Frame rate is
most often expressed in frames per second (FPS) and is also expressed in
progressive scan monitors as hertz (Hz).
Video
formats- A video format defines the way that video is recorded and
stores, it usually specifies: Codec/compressor, frame rate, frame size, frame
aspect ratio, pixel aspect ratio, scanning method (interlaced or progressive).
The most common formats are DV, HDV and AVCHD. Type-based files like DV and HDV
can be transferred to a computer for editing with Firewire without any
problems. However file-based formats like AVCHD are already stores as files
which then can be transferred to a computer for editing via USB or a card
reader.
Video
compression- Codec is short for coder-decoder and describes he method
which the video data is encoded into a files and then decoded when the file is
played back. Majority of videos are compressed during encoding and so the terms
codec and compressor are often used. Transcoding is the term used for the
process of converting from one codec to another. Codecs can be Lossless, which
means they do not throw any data away, or Lossy, which means that some data is
lost during encoding. Lossless codecs are
of higher quality than lossy codecs, however they produce larger files.