Samstag, 16. April 2011

EE4206/EE5806 Digital Image Processing : Three Data redundancy in 2-D intensity array

EE4206/EE5806 Digital Image Processing : Three Data redundancy in 2-D intensity array

1. . . . the number of bits needed to represent an image as a 2-D array of inetnsity values.

2. Coding redundancy : A code is a system of symbols used to represent a body of information or set of events. Each piece if information or event is assigned a sequence of code symbols, called a code word. The number of symbols in EACH code word is its length.

The 8-bit codes that are used to represent the intensities in most 2-D intensity arrays contain more bits than are needed to represent the intensities.

3. Spatial and temporal redundancy. Because the pixels of most 2-D intensity arrays are correlated spatially ( ie., each pixel is similar to or dependent on nighboring pixels), information is unnecessarily replicated in the representations of the correlated pixels.

In a video sequence, temporally correlated pixels ( ie., those similart to or dependent on pixels in nearby frames) also duplicate information.

4. irrelevant Information. Most 2-D intensity arrays contain information that is ignored by the human visual system and /or extraneous to the intended use of the image. It is redundane in the sense that it is not used.

excerpted from : Gonzales and Woods : Digital Image Processing, ch8., page 549.

[國事] 重案組出手 政治大搜捕塗鴉撐艾未未少女

內地異見藝術家艾未未「 被失蹤」至今 12天,海外聲援不絕。

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塗鴉絕非大案,但警方卻將案件交予專查殺人、綁架等大案的西九龍總區重案組接手,追緝少女歸案。有警隊中人指:「 呢單嘢好明顯係政治任務!」

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Image Compression

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