1 Misc Scripts

Display voltages and current flow:

./pac1720_info.sh

Output:

ZED_5V        	5.0781 V [2080] 	+29.0625 mV [2e8]   +968.75 mA
BETA_5V       	5.1172 V [20c0] 	+26.6016 mV [2a9]   +886.72 mA
HDN           	3.2422 V [14c0] 	 -0.0391 mV [fff]     -1.30 mA
PCIE_N_V      	3.2422 V [14c0] 	 -0.0391 mV [fff]     -1.30 mA
HDS           	3.2422 V [14c0] 	 +0.0000 mV [000]     +0.00 mA
PCIE_S_V      	3.2422 V [14c0] 	 -0.0391 mV [fff]     -1.30 mA
RFW_V         	3.2812 V [1500] 	 +0.2734 mV [007]     +9.11 mA
IOW_V         	3.2422 V [14c0] 	 +0.0000 mV [000]     +0.00 mA
RFE_V         	3.2812 V [1500] 	 +0.2344 mV [006]     +7.81 mA
IOE_V         	3.2812 V [1500] 	 +0.0781 mV [002]     +2.60 mA
VCCO_35       	2.5000 V [1000] 	 +0.6641 mV [011]    +22.14 mA
VCCO_13       	2.4609 V [ fc0] 	 +1.2500 mV [020]    +41.67 mA
PCIE_IO       	2.4609 V [ fc0] 	 -0.0391 mV [fff]     -1.30 mA
VCCO_34       	2.4609 V [ fc0] 	 +0.8203 mV [015]    +27.34 mA
W_VW          	1.9922 V [ cc0] 	 -0.0781 mV [ffe]     -2.60 mA
N_VW          	3.1641 V [1440] 	 +0.0000 mV [000]     +0.00 mA
N_VN          	1.8750 V [ c00] 	+15.4297 mV [18b]   +514.32 mA
N_VE          	3.1641 V [1440] 	 +0.0000 mV [000]     +0.00 mA
E_VE          	1.9922 V [ cc0] 	 -0.0391 mV [fff]     -1.30 mA
S_VE          	1.9531 V [ c80] 	 +0.0000 mV [000]     +0.00 mA
S_VS          	2.9297 V [12c0] 	 +0.3906 mV [00a]    +13.02 mA
S_VW          	1.9922 V [ cc0] 	 -0.1562 mV [ffc]     -5.21 mA

Read Temperature on Zynq:

./zynq_info.sh 

Output:

ZYNQ Temp     	49.9545 °C





2 Row noise correction using black reference columns

Using octave/matlab-like pseudocode.

2.1 For previous frame, compute:

For each row:

med_left(y)  = median(im(y,1:8))                   % median for first 8 columns
med_right(y) = median(im(y,end-7:end))             % median of last 8 columns

For the entire image:

offset_odd_left   = median(med_left(1:2:end))      % median of medians from odd left rows
offset_odd_right  = median(med_right(1:2:end))     % median of medians from odd right rows
offset_even_left  = median(med_left(2:2:end))      % median of medians from even left rows
offset_even_right = median(med_right(2:2:end))     % median of medians from even right rows

2.2 For current frame:

1. Subtract a dark frame (constant image)

im -= dark_frame

2. Fix black level offsets:

  • these are expected to change very slowly over time, not from frame to frame, so we are reusing them from previous frame to avoid multiple passes
  • subtract an offset for odd rows and another offset for even rows
  • the offset varies linearly from left to right
  • we will attempt to keep a constant black level: let's say target_black_level = 128
  • subtract these values from each row:
offset_odd(x)  = offset_odd_left + (offset_odd_right - offset_odd_left) * x / width - target_black_level;
offset_even(x) = offset_even_left + (offset_even_right - offset_even_left) * x / width - target_black_level;
im(1:2:end,x) -= offset_odd(x)
im(2:2:end,x) -= offset_even(x)

3. Fix dynamic row noise

  • this changes with every frame, and is not correlated from frame to frame
  • we have a noisy estimation of this row noise in the black reference columns
  • average black columns (16 values for each row):
mb(y) = mean(black_columns)(y) = mean(im(y, [1:8 end-7:end])
  • from each row, we will subtract a scalar value: k * mb(y), where k is 0.6 for gain x1:
im(y,:) -= k * mb(y)

Optional steps (to be tested):

  • apply a gain frame:
im = (im - target_black_level) .* gain_frame + target_black_level
  • apply a clip frame in overexposed highlights:
im(im > clip_thr) -= clip_frame(im > clip_thr)  % clip_thr is about 2500 for gain x1; smooth transition might be also needed
  • apply a look-up table (either per-channel or global):
im = lut(im)

That's it.

Doing the math on 16 bits is preferred, and when getting back to 12 bits, add one bit of random noise (better results). See pack12/unpack12 on raw2dng for details on the implementation, and http://theory.uchicago.edu/~ejm/pix/20d/tests/noise/noise-p3.html for the rationale behind it.






3 Clipping

scn_reg 28 0x00 # deactivate clipping
scn_reg 28 0x10 # activate low clipping
scn_reg 28 0x20 # activate high clipping
scn_reg 28 0x30 # activate high+low clipping