HDRi (data format)
Encyclopedia
The HDRi data format is a 64bit (color) or 32bit (greyscale) data format for saving RAW data of HDR scans including infrared data developed by LaserSoft Imaging
LaserSoft Imaging
LaserSoft Imaging AG is a software developer designing software such as SilverFast for scanners and digital cameras. The company's headquarters are located in Kiel, Germany, north of Hamburg, and another office in Sarasota, Florida, United States....

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Data format

Format Encoding Compression Color space Color depth
(Bit per pixel)
Dynamic range
(Dimensions of 10)
Relative
gradation
HDRi
(.tif, .tiff)
RGB (linear) none RGB
RGB color space
An RGB color space is any additive color space based on the RGB color model. A particular RGB color space is defined by the three chromaticities of the red, green, and blue additive primaries, and can produce any chromaticity that is the triangle defined by those primary colors...

 
64 = 48 + 16 (infrared channel) 4,8 0,0014 %
RGB (linear) none RGB
RGB color space
An RGB color space is any additive color space based on the RGB color model. A particular RGB color space is defined by the three chromaticities of the red, green, and blue additive primaries, and can produce any chromaticity that is the triangle defined by those primary colors...

 
32 = 16 + 16 (Infrared channel) 4,8 0,0014 %

Description

Some image scanner
Image scanner
In computing, an image scanner—often abbreviated to just scanner—is a device that optically scans images, printed text, handwriting, or an object, and converts it to a digital image. Common examples found in offices are variations of the desktop scanner where the document is placed on a glass...

s, especially film scanners provide an additional infrared channel. The data it collects during a scan can be used for image optimization, e.g. for scratch and dust removal
Infrared cleaning
Infrared cleaning is a technique used by some film scanners and flatbed scanners to reduce or remove the effect of dust and scratches upon the finished scan. It works by collecting an additional infrared channel from the scan at the same position and resolution as the three visible colour channels...

. The infrared RAW data and the usual image RAW data get saved in the HDRi data format, where 16bit per color channel are used for every pixel and additional 16bit for the infrared channel. Thus, a HDRI color file devotes resources of 64bit per pixel and a HDRi greyscale file 32bit per pixel.

Application

The infrared RAW data is saved lossless with the image RAW data. Therefore it isn't necessary to process them while scanning. This facilitates the digitalization of larger archives. Afterwards, the so filed originals can be post processed at any time with dust and scratch removal, possibly in batch mode.
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