Fixes in html files and manifest from 2000
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@@ -36,7 +36,7 @@
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{
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"file_path" : "lavabus.pgm",
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"inventory_order" : 100,
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"OK_to_edit" : true,
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"OK_to_edit" : false,
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"display_as" : "image",
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"display_via_github" : false,
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"entry_text" : "Kilauea volcano bus trapped in lava"
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@@ -44,7 +44,7 @@
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{
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"file_path" : "michael.pgm",
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"inventory_order" : 100,
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"OK_to_edit" : true,
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"OK_to_edit" : false,
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"display_as" : "image",
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"display_via_github" : false,
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"entry_text" : "image of author’s godchild and nephew"
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@@ -60,7 +60,7 @@
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{
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"file_path" : "lenna.glic",
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"inventory_order" : 150,
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"OK_to_edit" : true,
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"OK_to_edit" : false,
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"display_as" : "binary",
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"display_via_github" : false,
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"entry_text" : "P10 scan of 1972 Playboy centerfold"
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+17
-17
@@ -14,7 +14,7 @@
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## Try:
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In a video window (white text on black background):
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In a terminal window (white text on black background):
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``` <!---sh-->
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./try.sh
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@@ -33,7 +33,7 @@ The author recommended on linux/x86, glibc 2.0, libc4/5:
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``` <!---make-->
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bmeyer: bmeyer.c
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CC -DY="__setfpucw(0x127f)" -O6 $? -o $@ -lm
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cc -DY="__setfpucw(0x127f)" -O6 $? -o $@ -lm
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```
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However many compilers use `-O3` as the maximum level for `-O` optimization.
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@@ -74,9 +74,9 @@ This program is called `GLICBAWLS`
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Squares".
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And that's exactly what this program does --- feed it a .PGM file
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(either raw [i.e. P5] or ASCII [i.e. P2]) on stdin, and it will
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output a compressed version to stdout. Feed it a compressed file
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on stdin, and it will decompress it to stdout --- as either raw or
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(either raw [i.e. P5] or ASCII [i.e. P2]) on `stdin`, and it will
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output a compressed version to `stdout`. Feed it a compressed file
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on `stdin`, and it will decompress it to `stdout` --- as either raw or
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ASCII .PGM, depending on what format it was compressed from. For
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example:
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@@ -215,7 +215,7 @@ In short --- running it through the preprocessor and the
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pretty-printer will give you something that looks slightly less
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like line noise and slightly more like a C program, but unless you
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are a true wizard, it is unlikely to gain you any insights into
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what is actually going on....[^0]
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what is actually going on....[^1]
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### Bugs, Assumptions and TODO
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@@ -269,7 +269,7 @@ ordering. For each pixel, an expected value is calculated by creating a least
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squares predictor of order 12 based on all of the previously encoded/decoded
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pixels. However, the contribution of each pixel is weighted according to its
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[Manhattan-distance](https://en.wikipedia.org/wiki/Taxicab_geometry) from the
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current pixel, `D`. That weight used is `pow(0.8,D)`. [^1] [^2] [^3]
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current pixel, `D`. That weight used is `pow(0.8,D)`. [^2] [^3] [^4]
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In a similar way, the prediction *errors* for all previous pixels
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are combined --- a weighted average (with weight `pow(0.7,D)`) of
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@@ -293,27 +293,27 @@ arithmetic decoder provides the information which half the actual
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value is in. In both cases, the interval borders are adjusted
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accordingly, the arithmetic coder/decoder updated, and the
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interval halving repeated until the precise value has been
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en/decoded[^4].
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en/decoded[^5].
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[^0]: Yes, this could be seen as a challenge....
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[^1]: Actually, the weight is `pow(0.8,D)/s`, where `s` is the sigma
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[^1]: Yes, this could be seen as a challenge....
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[^2]: Actually, the weight is `pow(0.8,D)/s`, where `s` is the sigma
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used for encoding/decoding the particular previous pixel. Dividing
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by `s` is a rather arbitrary action justified only by the
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improvement in results. Mathematically, I can only justify
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dividing by `s^2`, or not dividing at all....
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[^2]: Obviously, these least squares predictors are not calculated
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[^3]: Obviously, these least squares predictors are not calculated
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from scratch for each pixel. Some clever reuse of earlier
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results allows `O(1)` calculation, rather than the
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`O(previous_rows*columns)` this description would suggest.
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[^3]: As anyone who has ever tried local least squares knows from
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[^4]: As anyone who has ever tried local least squares knows from
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bitter experience, there is a lot of numerical instability
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associated with them. So `glicbawls` adds a bias towards an
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averaging predictor to the equation system the least squares
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predictor is calculated from. The weight that is given to
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this bias is constantly adjusted throughout coding/decoding,
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thus justifying the 'a' in `glicbawls`.
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[^4]: In the case of near-lossless coding, the interval is not
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[^5]: In the case of near-lossless coding, the interval is not
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necessarily *halved*, but rather split at a convenient point
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(the split points are chosen in such a way as to minimise the
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expected number of bits needed for coding). Also, the
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@@ -324,7 +324,7 @@ en/decoded[^4].
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### Photo Credit:
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[Lavabus](lavabus.pgm) was taken by the judge, Landon Curt Noll.
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[Michael](michael.pgm) was provided by the author. [Lenna](%%REPO_URL%%/2000/bmeyer/lenna.glic) is a
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[Michael](michael.pgm) was provided by the author. [Lenna](lenna.glic) is a
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1972 Playboy centerfold (doesn't show very much).
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- [michael.pgm](michael.pgm)
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@@ -333,11 +333,11 @@ en/decoded[^4].
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- [lavabus.pgm](lavabus.pgm)
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A bus that was trapped by lava from [Kilauea
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volcano](https://en.wikipedia.org/wiki/Kīlauea) in Hawaii, US. Nobody was
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A bus that was trapped by lava from [Kīlauea
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volcano](https://en.wikipedia.org/wiki/Kīlauea) in Hawaii, US. Nobody was
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in the bus at the time, BTW. Photo date: 1981.
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- [lenna.glic](%%REPO_URL%%/2000/bmeyer/lenna.glic)
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- [lenna.glic](lenna.glic)
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A November 1972 Playboy centerfold was scanned in long ago and has been used
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for image compression research since then. Playboy originally threatened to
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@@ -412,7 +412,7 @@ Location: <a href="../../location.html#AU">AU</a> - <em>Commonwealth of Australi
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<h2 id="to-use">To use:</h2>
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<pre><code> ./bmeyer</code></pre>
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<h2 id="try">Try:</h2>
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<p>In a video window (white text on black background):</p>
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<p>In a terminal window (white text on black background):</p>
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<pre><code> ./try.sh</code></pre>
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<p>The script will suggest you compare the output of the program with images,
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prompting you to press any key to continue so that you may do so.</p>
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@@ -421,7 +421,7 @@ prompting you to press any key to continue so that you may do so.</p>
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dashed argument) for compression and decompression! You’ve been warned.</p>
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<p>The author recommended on linux/x86, glibc 2.0, libc4/5:</p>
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<pre><code> bmeyer: bmeyer.c
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CC -DY="__setfpucw(0x127f)" -O6 $? -o $@ -lm</code></pre>
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cc -DY="__setfpucw(0x127f)" -O6 $? -o $@ -lm</code></pre>
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<p>However many compilers use <code>-O3</code> as the maximum level for <code>-O</code> optimization.</p>
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<p>And on linux/x86, glibc 2.1:</p>
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<pre><code> bmeyer: bmeyer.c
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@@ -446,9 +446,9 @@ chance any given file produced might not be portable.</p>
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<p><code>GLICBAWLS</code> stands for “Grey Level Image Compression By Adaptive Weighted Least
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Squares”.</p>
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<p>And that’s exactly what this program does — feed it a .PGM file
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(either raw [i.e. P5] or ASCII [i.e. P2]) on stdin, and it will
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output a compressed version to stdout. Feed it a compressed file
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on stdin, and it will decompress it to stdout — as either raw or
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(either raw [i.e. P5] or ASCII [i.e. P2]) on <code>stdin</code>, and it will
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output a compressed version to <code>stdout</code>. Feed it a compressed file
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on <code>stdin</code>, and it will decompress it to <code>stdout</code> — as either raw or
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ASCII .PGM, depending on what format it was compressed from. For
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example:</p>
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<pre><code> ./glicbawls < michael.pgm > michael.glic</code></pre>
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@@ -614,16 +614,16 @@ interval halving repeated until the precise value has been
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en/decoded<a href="#fn5" class="footnote-ref" id="fnref5" role="doc-noteref"><sup>5</sup></a>.</p>
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<h3 id="photo-credit">Photo Credit:</h3>
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<p><a href="lavabus.pgm">Lavabus</a> was taken by the judge, Landon Curt Noll.
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<a href="michael.pgm">Michael</a> was provided by the author. <a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2000/bmeyer/lenna.glic">Lenna</a> is a
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<a href="michael.pgm">Michael</a> was provided by the author. <a href="lenna.glic">Lenna</a> is a
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1972 Playboy centerfold (doesn’t show very much).</p>
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<ul>
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<li><p><a href="michael.pgm">michael.pgm</a></p>
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<p>The author’s Godchild and nephew.</p></li>
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<li><p><a href="lavabus.pgm">lavabus.pgm</a></p>
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<p>A bus that was trapped by lava from <a href="https://en.wikipedia.org/wiki/Kīlauea">Kilauea
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<p>A bus that was trapped by lava from <a href="https://en.wikipedia.org/wiki/Kīlauea">Kīlauea
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volcano</a> in Hawaii, US. Nobody was
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in the bus at the time, BTW. Photo date: 1981.</p></li>
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<li><p><a href="https://github.com/ioccc-src/temp-test-ioccc/blob/master/2000/bmeyer/lenna.glic">lenna.glic</a></p>
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<li><p><a href="lenna.glic">lenna.glic</a></p>
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<p>A November 1972 Playboy centerfold was scanned in long ago and has been used
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for image compression research since then. Playboy originally threatened to
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prosecute unauthorized use, but eventually granted that, having been in use
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