Exposure correction – FastRawViewer Software 2.0 (Download) User Manual
Page 74
FastRawViewer
– user manual
Page 74 of 175
Copyright © 2014-2016, LibRaw LLC,
Exposure adjustments do not affect the display of underexposure areas (or underexposure statistics).
For this shot, part of the foreground is underexposed; also, one can see areas with the red channel
underexposed (red), and, also areas where both red and blue channels are underexposed (magenta).
Unlike for overexposure, which is determined fairly unambiguously in digital cameras (by the
“blowout” of one or more channels, the channel histogram pressed to the right edge and having a
characteristic spike), the limit of the unacceptable underexposure area cannot be exactly
determined, because it depends on
Planned print size.
Planned shadow boost in the current shot.
In
FastRawViewer
, the limit that controls the underexposure warning is set by the user themself in
the preferences (Preferences – Exposure – Underexposure detection limit). The default value (8EV)
is fairly conservative, and works pretty well for low ISO settings, 100-800 ISO. In the case of using
high ISO, or strict demands to the image quality, this parameter may to be set lower (to 6-7EV, and
sometimes even lower), according to the technical requirements for the resulting image.
Exposure correction
Adobe 'hidden
’
exposure correction
By default, an exposure correction equal to the one that is automatically applied by Adobe
converters is also applied when a RAW file is opened in
FastRawViewer
(for more details, please see
.
As a result, the overall brightness of the rendition on the screen is a close match to a JPEG preview;
and, given the contrast curve in Preferences is set to 'Variable Contrast' and contrast is set to default,
it also matches the rendition in Adobe converters with all the sliders there being set to '0'.
The application of this standard exposure offset can be switched off via Preferences – Exposure –
Apply Adobe hidden exposure correction.
Automatic exposure correction
If Shift-A is pressed, or Menu – Adjust – Auto Exposure Correction is enabled,
FastRawViewer
calculates and applies
automatic exposure correction in such a way, that 1% of the total amount of
pixels in the image are pushed to saturation (receive the value of 255 on the 8-bit scale).