Moteur de recherche de fiches techniques de composants électroniques |
|
ADV611 Fiches technique(PDF) 5 Page - Analog Devices |
|
ADV611 Fiches technique(HTML) 5 Page - Analog Devices |
5 / 46 page ADV611/ADV612 –5– REV. 0 BLOCK A IS HIGH PASS IN X AND DECIMATED BY TWO. BLOCK B IS HIGH PASS IN X, HIGH PASS IN Y, AND DECIMATED BY EIGHT. BLOCK C IS HIGH PASS IN X, LOW PASS IN Y, AND DECIMATED BY EIGHT. BLOCK D IS LOW PASS IN X, HIGH PASS IN Y, AND DECIMATED BY EIGHT. BLOCK E IS HIGH PASS IN X, HIGH PASS IN Y, AND DECIMATED BY 32. BLOCK F IS HIGH PASS IN X, LOW PASS IN Y, AND DECIMATED BY 32. BLOCK G IS LOW PASS IN X, HIGH PASS IN Y, AND DECIMATED BY 32. BLOCK H IS HIGH PASS IN X, HIGH PASS IN Y, AND DECIMATED BY 128. BLOCK I IS HIGH PASS IN X, LOW PASS IN Y, AND DECIMATED BY 128. BLOCK J IS LOW PASS IN X, HIGH PASS IN Y, AND DECIMATED BY 128. BLOCK K IS HIGH PASS IN X, HIGH PASS IN Y, AND DECIMATED BY 512. BLOCK L IS HIGH PASS IN X, LOW PASS IN Y, AND DECIMATED BY 512. BLOCK M IS LOW PASS IN X, HIGH PASS IN Y, AND DECIMATED BY 512. BLOCK N IS LOW PASS IN X, LOW PASS IN Y, AND DECIMATED BY 512. N M L K I H J G F E C B D A Figure 5. Modified Mallat Diagram (Block Letters Correspond to Those in Filter Tree) ENCODE PATH DECODE PATH WAVELET KERNEL FILTER BANK ADAPTIVE QUANTIZER RUN LENGTH CODER & HUFFMAN CODER COMPRESSED DATA Figure 4. Encode and Decode Paths References For more information on the terms, techniques and underlying principles referred to in this data sheet, you may find the follow- ing reference texts useful. A reference text for general digital video principles is: Jack, K., Video Demystified: A Handbook for the Digital Engineer (High Text Publications, 1993) ISBN 1-878707-09-4 Three reference texts for wavelet transform background infor- mation are: Vetterli, M., Kovacevic, J., Wavelets And Subband Coding (Prentice Hall, 1995) ISBN 0-13-097080-8 Benedetto, J., Frazier, M., Wavelets: Mathematics And Applica- tions (CRC Press, 1994) ISBN 0-8493-8271-8 Grossman, A., Morlet, J., Decomposition of Hardy Functions into Square Integrable Wavelets of Constant Shape, Siam. J. Math. Anal., Vol. 15, No. 4, pp 723-736, 1984 THE WAVELET KERNEL This block contains a set of filters and decimators that work on the image in both horizontal and vertical directions. Figure 8 illustrates the filter tree structure. The filters apply carefully chosen wavelet basis functions that better correlate to the broad- band nature of images than the sinusoidal waves used in Dis- crete Cosine Transform (DCT) compression schemes (JPEG, MPEG, and H261). An advantage of wavelet-based compression is that the entire image can be filtered without being broken into sub-blocks as required in DCT compression schemes. This full image filtering eliminates the block artifacts seen in DCT compression and offers more graceful image degradation at high compression ratios. The availability of full image subband data also makes image processing, scaling, and a number of other system fea- tures possible with little or no computational overhead. The resultant filtered image is made up of components of the original image as is shown in Figure 5 (a modified Mallat Tree). Note that Figure 5 shows how a component of video would be filtered, but in multiple component video, luminance and color components are filtered separately. In Figure 6 and Figure 7 an actual image and the Mallat Tree (luminance only) equivalent is shown. It is important to note that while the image has been filtered or transformed into the frequency domain, no compres- sion has occurred. With the image in its filtered state, it is now ready for processing in the second block, the quantizer. Understanding the structure and function of the wavelet filters and resultant product is the key to obtaining the highest perfor- mance from the ADV611/ADV612. Consider the following points: • The data in all blocks (except N) for all components are high pass filtered. Therefore, the mean pixel value in those blocks is typically zero and a histogram of the pixel values in these blocks will contain a single “hump” (Laplacian distribution). • The data in most blocks is more likely to contain zeros or strings of zeros than unfiltered image data. • The human visual system is less sensitive to higher frequency blocks than low ones. • Attenuation of the selected blocks in luminance or color com- ponents results in control over sharpness, brightness, contrast and saturation. • High quality filtered/decimated images can be extracted/created without computational overhead. Through leverage of these key points, the ADV611/ADV612 not only compresses video, but offers a host of application features. Please see the Applying the ADV611/ADV612 section for details on getting the most out of the ADV611/ADV612’s subband coding architecture in different applications. |
Numéro de pièce similaire - ADV611 |
|
Description similaire - ADV611 |
|
|
Lien URL |
Politique de confidentialité |
ALLDATASHEET.FR |
ALLDATASHEET vous a-t-il été utile ? [ DONATE ] |
À propos de Alldatasheet | Publicité | Contactez-nous | Politique de confidentialité | Echange de liens | Fabricants All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |