4 <title>ImageSqueeze - lossy image codec</title>
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198 <div class="row"><div class="col-md-9"><h1 class="title">ImageSqueeze - lossy image codec</h1>
201 <li><a href="http://www2.svjatoslav.eu/gitweb/?p=imagesqueeze.git;a=snapshot;h=HEAD;sf=tgz">download latest snapshot</a>
204 <li>This program is free software; you can redistribute it and/or modify it under
205 the terms of version 3 of the <a href="https://www.gnu.org/licenses/lgpl.html">GNU Lesser General Public License</a> or later as
206 published by the Free Software Foundation.
211 <li>Svjatoslav Agejenko
213 <li>Homepage: <a href="http://svjatoslav.eu">http://svjatoslav.eu</a>
215 <li>Email: <a href="mailto://svjatoslav@svjatoslav.eu">mailto://svjatoslav@svjatoslav.eu</a>
220 <li><a href="http://www.svjatoslav.eu/programs.jsp">other applications hosted at svjatoslav.eu</a>
224 <div id="outline-container-sec-1" class="outline-2">
225 <h2 id="sec-1"><span class="section-number-2">1</span> Overview</h2>
226 <div class="outline-text-2" id="text-1">
228 Lossy image codec. Optimized for photos. I developed it to test out an
229 image compression ideas.
233 I believe my <a href="#sec-2-1">algorighm has interesting advantages.</a>
237 Below are original photo and the same image being compressed down to
238 ~93 Kb and then decompressed.
243 <p><a href="originalAndCompressed.png"><img src="originalAndCompressed.png" class="img-responsive" alt="originalAndCompressed.png"></a>
248 When looking very closely, slight grainyness, loss of color precision
249 and blurriness (loss of detail) could be noticed as a compression
250 artifacts. Still sharp edges are always preserved. Also no blocks
251 typical to JPEG are ever seen. I think that is awesome result for
252 just ~ 2.5 bits per pixel on that color photo.
256 <div id="outline-container-sec-2" class="outline-2">
257 <h2 id="sec-2"><span class="section-number-2">2</span> Algorithm description</h2>
258 <div class="outline-text-2" id="text-2">
260 <li>Color image is split into three separate channels: Y, U and V.
262 <li>Each channel is independently compressed.
267 <li>Single channel compression method:
270 <li>Algorithm is inspired by <a href="https://en.wikipedia.org/wiki/Diamond-square_algorithm">diamond-square algorithm</a> that is meant to
271 produce random heightmap/plasma effect.
274 <li>During image compression: 2D image surface is iterated in the
275 similar manner to diamond-square algorithm. Average color from
276 neighbors is calculated and difference between neighbors average
277 and actual pixel color is saved. As the pixel grid becomes
278 gradually more dense, difference between neighbors tends to get
279 smaller, thereby requiring less bits per pixel for storing the
286 <div id="outline-container-sec-2-1" class="outline-3">
287 <h3 id="sec-2-1"><a id="ID-1d917f74-e763-4a71-976e-4aa60732efa6" name="ID-1d917f74-e763-4a71-976e-4aa60732efa6"></a><span class="section-number-3">2.1</span> Algorighm advantages</h3>
288 <div class="outline-text-3" id="text-2-1">
290 <li>It can be applied to any amount of dimensions, even for sound and
294 <li>Algorithm can operate in lossy and lossless mode.
297 <li>Algorithm naturally handles progressive loading. That is: low
298 resolution thumbnail of entire thing is immediately available and
299 gets gradually more dense during entire loading process.
302 <li>Algorithm naturally supports variable resolution. That is: different
303 areas can be encoded with different resolutions / pixel densities.
306 <li>Fast: Very little computations per pixel.
313 <div id="outline-container-sec-3" class="outline-2">
314 <h2 id="sec-3"><span class="section-number-2">3</span> <span class="label label-primary TODO">TODO</span> Things to improve</h2>
315 <div class="outline-text-2" id="text-3">
317 <li>Code documentation is weak.
320 <li>Better sample applications needed:
322 <li>Commandline image conversion utility.
329 <li>Add lossless support.
332 <li>Extract algorithm key parts into reusable library and make it
333 variable dimensional. So that the same code can be used for sound,
334 image and volumetric data compression/decompression.
339 </div><div class="col-md-3"><nav id="table-of-contents">
340 <div id="text-table-of-contents" class="bs-docs-sidebar">
342 <li><a href="#sec-1">1. Overview</a></li>
343 <li><a href="#sec-2">2. Algorithm description</a>
345 <li><a href="#sec-2-1">2.1. Algorighm advantages</a></li>
348 <li><a href="#sec-3">3. Things to improve</a></li>
353 <footer id="postamble" class="">
354 <div><p class="author">Author: Svjatoslav Agejenko</p>
355 <p class="date">Created: 2017-11-29 Wed 23:49</p>
356 <p class="creator"><a href="http://www.gnu.org/software/emacs/">Emacs</a> 25.1.1 (<a href="http://orgmode.org">Org-mode</a> 8.2.10)</p>