7. The processing chain 77
7
The processing
chain
The image processing is performed on-camera, both by the sensor and the embedded Field-Programmable
Gate Array (FPGA), saving computational power on your PC and leaving it available for the application.
Please refer to Section 8.10 for more information about camera controls such as white balance, digital
gain, etc. Figures 7.1 and 7.2 show the FPGA image processing chain in monochrome and color NECTA
cameras. The sensor performs some analog operations such as black level calibration, CDS gain and
analog gain.
The pre-processing operations involve calibration, ROI adjustments, binning and LUMA evaluation. At
the end of these steps, when RAW output is selected, the frame is directly sent through the USB channel
with no additional adjustment. Otherwise, the frame is further elaborated with the Image Processing
block, which applies pixelintensity adjustments such as white balance, gain, demosaicing, Look-Up Table
(LUT)s.
7.1 LIGHT METER
NECTA evaluates the compensation parameters (white balance, luma) over an image area called Light
Meter ROI (LMR). It is contained into the current ROI and usually coincides with it, but it can be limited
to a part of the ROI only to meet particular requirements (for example, to exclude a saturated region of
the image).
The data analyzed by the light meter are sampled before any transformation by image processing con-
trols such as digital gain, white balance, brightness, contrast and user LUT. Specifying the LMR requires
setting its position and size through the startX, startY, sizeX and sizeY parameters
1
.
1
Light meter ROI position coordinates are set with respect to the upper left point of the current ROI.
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