MPEG and JPEG Formates
MPEG Full Form
MPEG full form is Moving Picture Experts Group. It is a standard that is developed by the ISO/ IEC. It is basically used for compressing the audio and video content. There are different types of MPEG formats. Some of them are discussed below.
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(a) MPEG-1
This was the first standard that was developed for the audio, video compression. The quality provided by this format is very high.
(b) MPEG-2
This format of MPEG is considered to provide higher quality coding, sound, and image when compared to MPEG-I and hence it is highly used in the DVD industry and digital television
(c) MPEG Audio Layer-3
This format was basically created for compressing the audio files, It is popularly known as MP3. It predecessors were MP1 and MP2.
(d) MPEG-4
This format of MPEG supports all sorts of multimedia including audio, video, text, 3D content, etc. It is capable of streaming a high-quality video with minimum data rates and file sizes. It has the ability to embed a two-hour-long movie into a CD without compromising on the quality.
(e) MPEG-7
This MPEG format was used for explaining about the multimedia content that can be 3D content, audio, video, text, etc.
(f) MPEG-21
This format of MPEG is expected to become a standard for the multimedia framework.
JPEG Full Form
JPEG Full form is Joint Photographers Expert Group. This is considered to be a standard used for compressing an image, This compression is called ‘lossy’ compression. The process of compressing an image using this format involves the following four steps.
1. Initially, a red, green, blue image which is 16 x16 pixels in resolution will be transformed into a YUV image, where Y is the luminance component and UV is the chrominance component. The luminance component (Y) is nothing but the brightness of an image and it has a great impact on a human eye compared to the chrominance components. Once the transformation is complete an 8 x 8-pixel block will be obtained from 16 x 16 -pixel block.
2. Then, the 8 x 8 -pixel block will be further compressed by the Discrete Cosine Transformation (DCT). The DCT accomplishes the compression by transforming 8 x 8-pixel blocks into the frequency domains, wherein the components with low frequency will be moved to the upper left corner of the block and the components with higher frequency will be moved to the lower-left corner. Hence, the average value of every block is said to be present in the upper left corner. This implies that the values of the upper left corner can be used to determine the average value of each block. This average value is called DC value. Whereas, the remaining coefficient (63) are called AC values.
3. In this step, the coefficients will be made to undergo the process of quantization. This will quantize the coefficients into discrete levels. If the number of these levels is more then the compressed image then it is said to be closely matched with the original image.
4. Ultimately the coefficients in each of these levels belonging to a certain block will be compressed by using a particular encoding technique.
The process can be diagrammatical as follows.
RGB Image
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YUV Image
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DCT
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Quantization
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Encoding
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Compressed image
