- <h3>HDRI - floating point quality</h3>HDRI, or <a href="http://en.wikipedia.org/wiki/High_dynamic_range_imaging">High Dynamic Range Imaging</a>, was originally designed to more naturally represent our eyes ability to see both bright and dark areas of a scene simultaneously. In practical image processing terms it does a lot more than that. A HDRI version of IM (the default build) is compiled to use a floating point values for images stored in memory, to allow you to perform more exact HDRI handling of image operations, so as to prevent such operations 'clipping' the image colors at the extremes. HDRI uses the same color range as the default compile-time <a href="#quality">Quality Setting</a> for in memory storage. That is, values still range from '<code>0</code>' to the 'Quantum Range' as meaning black to white. But the values are saved using floating point ('<code>doubles</code>' in C programming terms) rather than integers, so that the 'quantum' effects from rounding off values into integers will not be seen. The values are also not 'clipped' when the values go beyond the 'Quantum Range' or into negatives. Basically you loose far less information between processing steps. HDRI is thus <i>vital</i> when you plan to use extremely heavy mathematical processing of images, involving the temporary use of negative values, or strong scaling to very small or very large values. It is especially important for users that want to make full use of <a href="../fourier/">Fast Fourier Transforms (FFT)</a> capabilities, and it is here that you will see the most examples of a HDRI version of IM, in these pages. For information of compiling a HDRI version of IM see <a href="http://magick.imagemagick.org/script/high-dynamic-range.php">Enabling HDRI in ImageMagick</a> on the main IM website, also for Windows and Ubuntu Linux specific information see <a href="../forum_link.cgi?f=4&t=14251">Fourier Transforms Announcement Discussion</a> on the user forums. One important operator that should be kept in mind when using HDRI is "<code><a href="../option_link.cgi?clamp">-clamp</a></code>". This option will clip the values in an image that fall outsize the normal range for images. That is, any negative value will be clipped to zero, and any value larger than 'QuantumRange' will be set to that value. It does NOT however 'round off' the floating-point values into integers. <a name="quantum_effects" id="quantum_effects"></a>
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