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HDR

Before 2016, HDR was understood as values outside the range (0 - 1.0f). Since there were no devices capable of achieving these values the only way available was to create digital images (in Blender, for example) or to merge multiple images with various dynamic ranges into a single HDR image. In 2016, with the arrival of sensors and monitors capable of extended dynamic ranges, HDR was standardized and there is the BT. 2100 color space that has gamut and color model like BT. 2020 but different transfer functions (gamma): Dolby Vision (HDR10), PQ and HLG. BT. 2100 considers values above 1.0f as illegal. There are two ways to return to legal values: clipping and tone-mapping. The BT.2100 color space is an efficient standard for encoding HDR colors, but it's not well suited for many rendering and composition (blending) operations.

CINELERRA-GG runs internally in 32-bit floating-point and thus can read and process values outside the range (0 - 1.0f ). However, there are plugins and tools that can introduce clipping that must be taken into account to keep the whole pipeline which preserves the original values. The manual indicates which plugins limit pixel values in the range (0, 1.0f ). The easiest way to see if a media is out of (0 - 1.0f ) range is to use the eyedropper tool (Get Color) in the Compositor window. If we use HDR media and need to do a Tone Mapping to make the pixel values fall within the range (0, 1.0), we can use the Blender Program plugin and, inside it, load the function (found in =>Syslib) tone_mapping.bp. Instructions for using this function can be found here at example 6.