#218 ConvertTo24Bits causes excessive darkening on 48-bit images

None
closed
Hervé Drolon
None
5
2013-09-01
2012-11-13
Nathanael Jones
No

I'm attempting to convert a 48-bit NEF file to 24-bit form; however, the result is much darker than the original, roughly 1/4th the luminosity.

This is a RAW sample file from http://www.rawsamples.ch/index_en.php

The direct URL is http://www.rawsamples.ch/raws/nikon/d3x/RAW_NIKON_D3X.NEF

Result is attached.

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Discussion

  • Hervé Drolon
    Hervé Drolon
    2013-09-01

    • status: open --> closed
    • assigned_to: Hervé Drolon
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  • Hervé Drolon
    Hervé Drolon
    2013-09-01

    Hi,

    For 48-bit to 24-bit conversion, you need to use a tone mapping conversion.
    See e.g. FreeImage_TmoDrago03 using a gamma = 1.

    Hervé