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| std:compression:start [2017/05/16 15:31] – kunkel | std:compression:start [2020/08/13 17:09] (current) – external edit 127.0.0.1 | ||
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| - | The goal of this effort | + | The goal of this effort |
| {{ : | {{ : | ||
| In detail: | In detail: | ||
| * Identification all quantities that are -- from the user-perspective -- useful to be set on a compression algorithm, i.e., they help users to control the compression rate and performance. | * Identification all quantities that are -- from the user-perspective -- useful to be set on a compression algorithm, i.e., they help users to control the compression rate and performance. | ||
| - | * Define these quantities properly and assign | + | * Define these quantities properly and assign |
| * Foster development of APIs and tools that use these quantities | * Foster development of APIs and tools that use these quantities | ||
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| Our strategy and timeline for establishing these conventions are as follows: | Our strategy and timeline for establishing these conventions are as follows: | ||
| - | * Identification | + | * Identification |
| * Invite international experts to this effort | * Invite international experts to this effort | ||
| * Identify relevant quantities | * Identify relevant quantities | ||
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| ===== Quantities ===== | ===== Quantities ===== | ||
| - | The following list of quantities contains candidates for the standardization. | + | The following list of quantities contains candidates for the standardisation. |
| They can be classified into: 1) accuracy/ | They can be classified into: 1) accuracy/ | ||
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| These quantities define the tolerable error on individual values or multidimensional fields of data from a given datatype. | These quantities define the tolerable error on individual values or multidimensional fields of data from a given datatype. | ||
| - | The definition is mostly based on the notion of the term error, which is the residual when subtracting the (lossy) compressed value (c) from the true value (v). | + | The definition is mostly based on the notion of the term error, which is the residual when subtracting the (lossy) compressed value (d) from the true value (v). |
| - | * **Absolute error tolerance**: | + | * **Absolute error tolerance**: |
| + | * **Relative error tolerance** is a measure of absolute error compared to the size of the calculations. | ||
| + | * **Relative error with finest absolute tolerance** is a combination of two quantities. With a relative tolerance, small numbers around 0 are problematic for compressors, | ||
| + | * **Precision bits and precision digits** indicates how much bits or decimal digits are required to represent the array values. | ||
| + | * **Mean squared error (MSE)** is the arithmetic mean of squared errors between uncompressed and original values; | ||
| + | * **Standard deviation** is the square root of the mean squared error. | ||
| + | * **Average absolute deviation** summarises the statistical dispersion or variability. | ||
| + | * **Peak signal-to-noise ratio (PSNR)** is the ratio between the maximum possible power of a signal and the power of corrupting noise that affects the fidelity of its representation. | ||
| + | * **Preserved values** , which must be preserved literally, i.e., they cannot be changed and must be preserved, i.e., only lossless compression can be applied to those values. | ||
| ==== Performance quantities ==== | ==== Performance quantities ==== | ||
| + | * **Compression/ | ||
| ==== Other quantities ==== | ==== Other quantities ==== | ||
| - | * **Rate limitation**: Defines | + | * **Rate limitation** |
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