Silicon Imaging SI-2K, User Manual

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ShootingwiththeSI-2K
SI 2K Manual
The layer-based approach of the CineForm RAW™ codec allows a host pro-
gram that does not have the ability to natively work with RAW data, such as
all current NLE systems and post-compositing tools, to work with the RAW
file formats as if it was another native RGB/YUV codec file by “wrapping” the
RAW data in an AVI or QuickTime format and then presenting that data to the
program in a native format it can read.
The RAW RGB format conversion is done on-the-fly in real-time at the codec
level, and at 32-bit perchannel floating point resolution, allowing for super white
and black values to be preserved. Because the host application sees the RAW
data through the codec wrapper as native RGB or YUV data, normal filters and
effects in the host application can be applied to the image without destroying
the underlying RAW data information.
Should a filter (Layer 3 in Figure 5.1) or the .look file 3D LUT (Layer 2 in Figure
5.1) “clip” data that is still present in the RAW data (Layer 1 in Figure 5.1), the
CineForm RAW codec is able to preserve the over-white values in it’s native 32-
bit floating point processing color-space. In applications that are 32-bit floating
point aware, these clipped values can be brought back into the visual space by
additional dynamic range compressing filters.
Exposure Meters
SiliconDVR provides three methods to give the user feedback for exposure
control. There is a Spot Meter which reads back an average luminance value
for a 10x10 pixel area, a False color 6-zone meter for allow the user to see what
pixels are falling in a given luminance range in the context of the entire image
(rather than a waveform which is an abstraction that does not allow the user to
actually see what pixel values are exposed at a given value in the context of the
image), and an on-screen RGB/CMY histogram display.
To use the Spot Meter, click on the SPOT METER button in the lower left-hand
corner of the main screen. A box will appear on-screen showing the luminance
value that corresponds to an average of the center 10-pixels. By clicking on the
screen, the spot meter can be moved around to various locations and used to
sample different points of the scene for exposure values. The scale of the spot
meter is from 0-100%
The 6-zone false color exposure meter is used to visualize the luminance value
of a given pixel in the context of the scene. Dark blue values are for shadow ar-
eas below 20% luminance, and the scale increases through various colors until
red is reached, representing near clipping and clipped values. The zone meter
is a continuous gradient, where-cross-over values allow the DP to see exactly
where on the scale of 0%-100% a pixel value is exposed at, rather than thresh-
old values which would only show what given zone a pixel is being exposed at.