HA1 - Task 1

HA1 – Task One

There are a lot of motion graphics and the ones that I am going to talk about are:

·         Pixel

·         Resolution

·         Screen Ratios

·         Frame Rate

·         Video Formats

·         Compression

Pixel

Firstly we have Pixel, it is used in; digital imaging and a raster image. A pixel is a physical point in a raster image, or the smallest addressable elements in a display device; so it is the smallest controllable element of a picture represented on the screen. The address of a pixel corresponds to its physical coordinates.

A pixel can only be one colour at a time but since they are small, they blend together and they make several of shades and blends of colours. The number of colours each pixel can be is determined by the number of bits used to represent it.

Bits

A bit (short for binary digit) is the smallest unit of data in a computer. A bit has a single binary value, either 0 or 1.

Although computers usually provide instructions that can test and manipulate bits, they generally are designed to store data and execute instructions in bit multiples called bytes.

In most computer systems, there are eight bits in a byte. The value of a bit is usually stored as either above or below a designated level of electrical charge in a single capacitor within a memory device.

Resolution

Resolution is the quality of the image and how sharpness of it, it mostly refers to resolution by monitors and printers.

Bitmap images are composed of pixels. Image resolution is simply the number of Pixels Per Inch (PPI) in the bitmap grid.

There are two aspects to every bitmap image - its size (width and height in inches) and resolution (the number of pixels per inch).

These two factors alone determine the total number of pixels in an image.

The more pixels there are in an image, the more detail the image can be displayed with.

The fewer pixels there are in an image, the less detail the image can be displayed with. There are two ways to display an image - on screen and in print.

Screen Ratio 

 The aspect ratio of a screen or image describes the proportional relationship between its width and its height. 

Frame Rate

The human eye and its brain interface, the human visual system, can process 10 to 12 separate images per second, perceiving them individually. Early silent films had a frame rate from 14 to 24 FPS which was enough for the sense of motion, but it was perceived as jerky motion.

Frame Rate tells you how many frames per second there are when recording or playing video.

Video cameras in Europe use 25 frames per second (fps). In USA & Japan 29.97fps or 30fps is used.

Animation works by recording each frame individually (e.g. with a stills camera) and then playing them back at a frame rate.

Animators often work with a lower frame rate (e.g. 12fps) so less frames are needed for the same length video clip.

If you change the frame rate of a 12fps video clip to 25fps, e.g. by adding it to a 25fps editing project, each frame will be repeated to keep the clip the same duration.

Video Format

Tape-based formats such as DV and HDV can be transferred to a computer for editing via Firewire.

A video format defines the way in which video is recorded and stored. It normally specifies:

·         Codec/compressor

·         Frame rate

·         Frame size

·         Frame aspect ratio

·         Pixel aspect ratio

·         Scanning method (interlaced or progressive)

Compression

Codec is short for coder-decoder and describes the method in which video data is encoded into a file and decoded when the file is played back.

Most video is compressed during encoding, and so the terms codec and compressor are often used interchangeably.

Transcoding is the process of converting from one codec to another.

Codecs can be Lossless, which means that they do not throw away any data, or Lossy, which means that data is lost during encoding.

Lossless codecs are higher quality than lossy codecs, but produce larger file sizes.

In a video workflow, you should avoid transcoding to a lossy codec until final output.

Codec	Lossiess	Recommed Use
DV-PAL	No	Capture/edit/output of DV-PAL video from the camera; archive DV-PAL video
HDV	No	Capture/edit/output of HDV video from camera; archive HDV video
H.264	No	Transcode video for web & computer playback (not suitable for editing)
MPEG-2	No	Transcode video for DVD
Animation	Yes	Output/archive video (mainly motion graphics, animation, etc) from After Effects, Photoshop
Apple Intermediate Codec	Yes	Transcode AVCHD/H.264 video for editing; output/archive video
Apple ProRes 422 (Proxy)	Yes	Transcode AVCHD/H.264 video for editing; output/archive video
Apple ProRes 422 (LT)	Yes	Transcode AVCHD/H.264 video for editing; output/archive video

Video Compositing

A quick paragraph from Wikipedia says that video compositing is “Compositing is the combining of visual elements from separate sources into single images, often to create the illusion that all those elements are parts of the same scene. Live-action shooting for compositing is variously called "chroma key", "blue screen", "green screen" and other names. Today, most, though not all, compositing is achieved through digital image manipulation. Pre-digital compositing techniques, however, go back as far as the trick films of Georges Méliès in the late 19th century; and some are still in use.” 

Four images of the same subject with original backgrounds removed and placed over a new background