https://wiki.multimedia.cx/index.php?title=Mean_Removal&feed=atom&action=history
Mean Removal - Revision history
2024-03-29T12:19:58Z
Revision history for this page on the wiki
MediaWiki 1.39.5
https://wiki.multimedia.cx/index.php?title=Mean_Removal&diff=7648&oldid=prev
Multimedia Mike: Reverted edits by Xd7Au2 (Talk); changed back to last version by Multimedia Mike
2007-04-11T04:26:23Z
<p>Reverted edits by <a href="/index.php/Special:Contributions/Xd7Au2" title="Special:Contributions/Xd7Au2">Xd7Au2</a> (<a href="/index.php?title=User_talk:Xd7Au2&action=edit&redlink=1" class="new" title="User talk:Xd7Au2 (page does not exist)">Talk</a>); changed back to last version by <a href="/index.php/User:Multimedia_Mike" title="User:Multimedia Mike">Multimedia Mike</a></p>
<table style="background-color: #fff; color: #202122;" data-mw="interface">
<col class="diff-marker" />
<col class="diff-content" />
<col class="diff-marker" />
<col class="diff-content" />
<tr class="diff-title" lang="en">
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 21:26, 10 April 2007</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l11">Line 11:</td>
<td colspan="2" class="diff-lineno">Line 11:</td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Add the elements and divide by the number of elements to obtain the vector mean (only use the integer portion of the quotient, i.e., round towards 0):</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Add the elements and divide by the number of elements to obtain the vector mean (only use the integer portion of the quotient, i.e., round towards 0):</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div> (17 <del style="font-weight: bold; text-decoration: none;"> </del>24 <del style="font-weight: bold; text-decoration: none;"> </del>18 <del style="font-weight: bold; text-decoration: none;"> </del>16 <del style="font-weight: bold; text-decoration: none;"> </del>11 <del style="font-weight: bold; text-decoration: none;"> </del>25 <del style="font-weight: bold; text-decoration: none;"> </del>20 <del style="font-weight: bold; text-decoration: none;"> </del>17 <del style="font-weight: bold; text-decoration: none;"> </del>12 <del style="font-weight: bold; text-decoration: none;"> </del>20 <del style="font-weight: bold; text-decoration: none;"> </del>22 <del style="font-weight: bold; text-decoration: none;"> </del>19 <del style="font-weight: bold; text-decoration: none;"> </del>15 <del style="font-weight: bold; text-decoration: none;"> </del>19 <del style="font-weight: bold; text-decoration: none;"> </del>23 <del style="font-weight: bold; text-decoration: none;"> </del>21) / 16 = 299 / 16 = 18</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div> (17 <ins style="font-weight: bold; text-decoration: none;">+ </ins>24 <ins style="font-weight: bold; text-decoration: none;">+ </ins>18 <ins style="font-weight: bold; text-decoration: none;">+ </ins>16 <ins style="font-weight: bold; text-decoration: none;">+ </ins>11 <ins style="font-weight: bold; text-decoration: none;">+ </ins>25 <ins style="font-weight: bold; text-decoration: none;">+ </ins>20 <ins style="font-weight: bold; text-decoration: none;">+ </ins>17 <ins style="font-weight: bold; text-decoration: none;">+ </ins>12 <ins style="font-weight: bold; text-decoration: none;">+ </ins>20 <ins style="font-weight: bold; text-decoration: none;">+ </ins>22 <ins style="font-weight: bold; text-decoration: none;">+ </ins>19 <ins style="font-weight: bold; text-decoration: none;">+ </ins>15 <ins style="font-weight: bold; text-decoration: none;">+ </ins>19 <ins style="font-weight: bold; text-decoration: none;">+ </ins>23 <ins style="font-weight: bold; text-decoration: none;">+ </ins>21) / 16 = 299 / 16 = 18</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>For the mean removal part, subtract the mean of 18 from each element in the vector:</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>For the mean removal part, subtract the mean of 18 from each element in the vector:</div></td></tr>
</table>
Multimedia Mike
https://wiki.multimedia.cx/index.php?title=Mean_Removal&diff=7645&oldid=prev
Xd7Au2 at 02:50, 11 April 2007
2007-04-11T02:50:41Z
<p></p>
<table style="background-color: #fff; color: #202122;" data-mw="interface">
<col class="diff-marker" />
<col class="diff-content" />
<col class="diff-marker" />
<col class="diff-content" />
<tr class="diff-title" lang="en">
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 19:50, 10 April 2007</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l11">Line 11:</td>
<td colspan="2" class="diff-lineno">Line 11:</td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Add the elements and divide by the number of elements to obtain the vector mean (only use the integer portion of the quotient, i.e., round towards 0):</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Add the elements and divide by the number of elements to obtain the vector mean (only use the integer portion of the quotient, i.e., round towards 0):</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div> (17 <del style="font-weight: bold; text-decoration: none;">+ </del>24 <del style="font-weight: bold; text-decoration: none;">+ </del>18 <del style="font-weight: bold; text-decoration: none;">+ </del>16 <del style="font-weight: bold; text-decoration: none;">+ </del>11 <del style="font-weight: bold; text-decoration: none;">+ </del>25 <del style="font-weight: bold; text-decoration: none;">+ </del>20 <del style="font-weight: bold; text-decoration: none;">+ </del>17 <del style="font-weight: bold; text-decoration: none;">+ </del>12 <del style="font-weight: bold; text-decoration: none;">+ </del>20 <del style="font-weight: bold; text-decoration: none;">+ </del>22 <del style="font-weight: bold; text-decoration: none;">+ </del>19 <del style="font-weight: bold; text-decoration: none;">+ </del>15 <del style="font-weight: bold; text-decoration: none;">+ </del>19 <del style="font-weight: bold; text-decoration: none;">+ </del>23 <del style="font-weight: bold; text-decoration: none;">+ </del>21) / 16 = 299 / 16 = 18</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div> (17 <ins style="font-weight: bold; text-decoration: none;"> </ins>24 <ins style="font-weight: bold; text-decoration: none;"> </ins>18 <ins style="font-weight: bold; text-decoration: none;"> </ins>16 <ins style="font-weight: bold; text-decoration: none;"> </ins>11 <ins style="font-weight: bold; text-decoration: none;"> </ins>25 <ins style="font-weight: bold; text-decoration: none;"> </ins>20 <ins style="font-weight: bold; text-decoration: none;"> </ins>17 <ins style="font-weight: bold; text-decoration: none;"> </ins>12 <ins style="font-weight: bold; text-decoration: none;"> </ins>20 <ins style="font-weight: bold; text-decoration: none;"> </ins>22 <ins style="font-weight: bold; text-decoration: none;"> </ins>19 <ins style="font-weight: bold; text-decoration: none;"> </ins>15 <ins style="font-weight: bold; text-decoration: none;"> </ins>19 <ins style="font-weight: bold; text-decoration: none;"> </ins>23 <ins style="font-weight: bold; text-decoration: none;"> </ins>21) / 16 = 299 / 16 = 18</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>For the mean removal part, subtract the mean of 18 from each element in the vector:</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>For the mean removal part, subtract the mean of 18 from each element in the vector:</div></td></tr>
</table>
Xd7Au2
https://wiki.multimedia.cx/index.php?title=Mean_Removal&diff=4871&oldid=prev
Multimedia Mike: /* Theory */ clarify rounding
2006-05-06T20:46:48Z
<p><span dir="auto"><span class="autocomment">Theory: </span> clarify rounding</span></p>
<table style="background-color: #fff; color: #202122;" data-mw="interface">
<col class="diff-marker" />
<col class="diff-content" />
<col class="diff-marker" />
<col class="diff-content" />
<tr class="diff-title" lang="en">
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 13:46, 6 May 2006</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l9">Line 9:</td>
<td colspan="2" class="diff-lineno">Line 9:</td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> 15 19 23 21</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> 15 19 23 21</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Add the elements and divide by the number of elements to obtain the vector mean:</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Add the elements and divide by the number of elements to obtain the vector mean <ins style="font-weight: bold; text-decoration: none;">(only use the integer portion of the quotient, i.e., round towards 0)</ins>:</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> (17 + 24 + 18 + 16 + 11 + 25 + 20 + 17 + 12 + 20 + 22 + 19 + 15 + 19 + 23 + 21) / 16 = 299 / 16 = 18</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> (17 + 24 + 18 + 16 + 11 + 25 + 20 + 17 + 12 + 20 + 22 + 19 + 15 + 19 + 23 + 21) / 16 = 299 / 16 = 18</div></td></tr>
</table>
Multimedia Mike
https://wiki.multimedia.cx/index.php?title=Mean_Removal&diff=4859&oldid=prev
Multimedia Mike at 15:47, 6 May 2006
2006-05-06T15:47:18Z
<p></p>
<p><b>New page</b></p><div>Mean removal is another one of those concepts -- like [[Differential Coding|differential coding]] -- that sounds like it would be difficult to understand. It’s not.<br />
__TOC__<br />
== Theory ==<br />
What is a mean? It’s an average. It’s the sum of n items divided by n. Not difficult. Removal in this context is just mathematical subtraction. To remove a mean from, say, a vector of numbers, sum the numbers, divide the sum by the number of elements in the vector, and subtract that number from each element in the vector. An example vector:<br />
<br />
17 24 18 16<br />
11 25 20 17<br />
12 20 22 19<br />
15 19 23 21<br />
<br />
Add the elements and divide by the number of elements to obtain the vector mean:<br />
<br />
(17 + 24 + 18 + 16 + 11 + 25 + 20 + 17 + 12 + 20 + 22 + 19 + 15 + 19 + 23 + 21) / 16 = 299 / 16 = 18<br />
<br />
For the mean removal part, subtract the mean of 18 from each element in the vector:<br />
<br />
-1 6 0 -2<br />
-7 7 2 -1<br />
-6 2 4 1<br />
-3 1 5 3<br />
<br />
This is the mean-removed vector. Just as with differential coding, the primary purpose is to make the numbers small. From here, the video codec needs to figure out efficient ways to transmit the mean-removed vector (also called the residual) as well as the vector mean. Encoding the residual will often result in information loss. However, the most significant number is the mean of the whole vector which should be transmitted losslessly.<br />
<br />
== What A Multimedia Hacker Needs To Know ==<br />
Mean removal seems to be pretty rare in production video codecs. One known codec that employs the technique is [[Sorenson Video 1]].<br />
<br />
[[Category:Compression Theory]]</div>
Multimedia Mike