Itala | INSTRUCTION MANUAL
acting on gains/offset as follow:
R
′
G
′
B
′
=
Gain00 Gain01 Gain02
Gain10 Gain11 Gain12
Gain20 Gain21 Gain22
R
G
B
+
Offset
0
Offset
1
Offset
2
where R’, G’ and B’ are the corrected color coordinates, while R, G and B are the uncorrected ones.
Gains and Offsets can be freely edited by the user but, in order to obtain an excellent calibration,
a wizard has been already developed and available in Itala View. Please refer to Paragraph 4.7.6 to
see the steps of this calibration procedure.
The color correction matrix is also use to make conversions between color spaces: for example, if
a YUV pixel format is selected, the camera automatically load the right coefficients to switch from
RGB to YUV color space:
Y
U
V
=
0.299 0.587 0.114
−0.147 − 0.289 0.436
0.615 − 0.515 − 0.100
R
G
B
+
0
128
128
For the proper adjustment of the CCM coefficients refer to section 4.7.6.
6.7.2 How to perform a correct color calibration
In order to perform a correct color calibration with Itala cameras, Itala View can be used and the
following steps can be performed:
1. Given a proper lighting, select the Horizontal line profile tab (central lower panel) and draw a
ROI which includes only the grayscale values on the bottom of the color checker (Figure 61).
2. Each greyscale tile of the displayed image should match the reference value imposed by the
color checker.
Therefore it’s necessary to adjuct ExposureTime and Gamma values in order to achieve this
perfect match (Figure 62). For now, consider only the green channel (current pixel values are
displayed at the bottom right of the image display panel).
3. After the green channel has been properly adjusted, use the BalanceRatioSelector and the
BalanceRatio features to do the same operation for the red and blue color channels.
Avoid the Balance white auto feature for this step and keep monitored the Horizontal line
profile tab. When the R, G and B curves are superimposed, the white balance is optimal (Figure
63).
4. Now the color calibration can be performed by using the dedicated wizard in the Tool panel
of Itala View: the instructions for the proper use of the Color Correction Wizard are listed in
Paragraph 4.7.6 (Figure 64).
Once the calibration is complete, the result will be similar to the following one depicted in
Figure 65.
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