Image Engineering camSPECS User Manual page 20

iQ-LED Settings:
1. Since the spectral sensitivity of typical modules has been measured above, the spectral sensitivity
wavelength range is known. Once an iQ-LED V2 device and spectrometer are connected to the
computer, launch the iQ-LED software v3.3 and allow for warmup.
2. Select the first LED (blue) for which the camera has sensitivity. Set its power to 95% with all other LEDs
set to 0 and drag the Current Illuminant to the Stored Illuminant panel. Repeat for only those LEDs for
which the camera has sensitivity resulting in a series of individual LED stored illuminants at 95/0% power
over only the camera spectral sensitivity wavelength range. Do not include LEDs whose peak output lies
outside the camera spectral sensitivity wavelength range.
3. Since the stored illuminants are the reference for these LEDs, use the Stored Illuminant panel to select
the just created stored illuminants. With a mouse-right-click, select Export selected illuminant(s)
reference spectra to a new folder.
4. Within Create Illuminant, 1) select spectral distribution A and 2) select intensity corresponding to
95% of maximum Illuminance [lx] shown after selecting circle i. Drag the Current Illuminant to the
Stored Illuminant panel. The spectral measurement panel will show the reference illuminant and the
created spectrum. Since the reference and actual spectra are not the same, use the File Save icon in
the upper left of the measurement panel to save the measured spectrum. Repeat for Illuminants D65
and E. Confirm that the red triangle with "!" is not displayed.
5. Rename all the saved stored illuminant text files in the folder to follow the naming convention
(text_number) and order (short to long wavelengths, A, D65, E) illustrated in column A of the spreadsheet
below.
6. When the camera module is placed directly at the exit port of the iQ-LED device and all ambient light is
excluded, perform captures of each stored illuminant in the order above and with exposure set for
adequate headroom for the brightest illuminant. Save these images using the naming convention
text_number.ext so that the numbering order is the same as the capture order specified.
7. Launch the camSPECS software Spectral sensitivity (iQ-LED) module and load the dark frame, image
folder, and spectra folder as described below. With the default settings, click Start, and after completion,
open the cameraRGBs.txt file output in the images folder, illustrated in columns C:E below.
8. Inspect to ensure that these values do not exceed 75% of the valid linear encoding range, including any
black offset associated with the dark frame. Inspect the maximum values illustrated in column F below to
ensure that the maximum camera response to each stored illuminant is approximately balanced.
9. The maximum camera response to each stored illuminant should be approximately balanced to achieve
proper neutral balance in subsequent spectral sensitivity determination reliably. The estimated adjusted
powers will create approximate balance as illustrated in column H. Create a new set of stored
illuminants with these powers (minimum 15%), increase exposure proportionately, and repeat steps 5-8
above. Confirm that the maximum camera response to each newly adjusted stored illuminant is
approximately balanced, as illustrated in columns I:L.
10. The existing stored illuminants must be deleted and recreated anytime an iQ-LED device is recalibrated.
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