Autoluma Process - Polaroid 8035 Repair Manual

8K Series ProPalette Repair Manual Theory of Operation
The Debugger is started, using the second serial port for talking to the remote debugger
which is running on the host.
When the switches are set to Control Code or Expansion Code, the EPROM version of
the Flash Dispatcher gets control.
If the switches are set for Control Code, the Flash Dispatcher moves the CNTRL_CODE
data block to DRAM and starts executing the code.
If the switches are set for Expansion Code, the EXPANSION_SWITCH data type is read
from flash. The data block in the EXPANSION_SWITH data type contains two pieces of
data; a program to run and a flag indicating whether this program should be directly
executed or whether it should be run using the debugger.

Autoluma Process

The autoluma calibration process measures the light emitted by the CRT using a photo
detector. This is done by varying the luma control output (G1) and video output while
scanning the CRT. The clear window of the filter wheel is in front of the solar cell at this
time to maximize the light measured by the solar cell.
The autoluma calibration process creates a data curve of video DAC input level vs. CRT
brightness (from the darkest to the brightest amount of light needed to expose the film
type chosen for the image). This curve is used to create a lookup table that maps pixel
values to video DAC values.
If the calibration process cannot find a CRT light level dark enough for the film, (i.e.
there is always light recorded by the solar cell) an error of "CRT not dim enough" will be
reported by the film recorder.
If the calibration process cannot find a CRT light level bright enough for the film (this
could mean that no light is emitted by the CRT), an error of "CRT not bright enough"
will be reported by the film recorder.
If the measured curve is not monotonically increasing from darker to brighter values, the
errors "luma not smooth" or "video not smooth" will be reported by the film recorder.
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