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copied!<p>By its nature, spline is an approximation. You can reduce the number of splines you use to reach a higher compression ratio.</p> <p>You can also achieve lossless compression by using some kind of encoding scheme. I am just making this up as I am typing, using the range example in previous answer (1000 for x and 400 for y),</p> <ol> <li>Each point only needs 19 bits (10 for x, 9 for y). You can use 3 bytes to represent a coordinate.</li> <li>Use 2 byte to represent displacement up to +/- 63.</li> <li>Use 1 byte to represent short displacement up to +/- 7 for x, +/- 3 for y.</li> </ol> <p>To decode the sequence properly, you would need some prefix to identify the type of encoding. Let's say we use 110 for full point, 10 for displacement and 0 for short displacement.</p> <p>The bit layout will look like this,</p> <pre><code>Coordinates: 110xxxxxxxxxxxyyyyyyyyyy Dislacement: 10xxxxxxxyyyyyyy Short Displacement: 0xxxxyyy </code></pre> <p>Unless your sequence is totally random, you can easily achieve high compression ratio with this scheme.</p> <p>Let's see how it works using a short example.</p> <p>3 points: A(500, 400), B(550, 380), C(545, 381)</p> <p>Let's say you were using 2 byte for each coordinate. It will take 16 bytes to encode this without compression.</p> <p>To encode the sequence using the compression scheme,</p> <p>A is first point so full coordinate will be used. 3 bytes. B's displacement from A is (50, -20) and can be encoded as displacement. 2 bytes. C's displacement from B is (-5, 1) and it fits the range of short displacement 1 byte.</p> <p>So you save 10 bytes out of 16 bytes. Real compression ratio is totally depending on the data pattern. It works best on points forming a moving path. If the points are random, only 25% saving can be achieved.</p>

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