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Introduction

The Demo Headboard Tuning tool is used to program a sensor headboard's EEPROM with Lens Shading Correct (LSC) coefficients to ensure image quality. The resulting settings are also stored in an INI file.

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Once a good image is shown in DevWare, the Demo Headboard Tuning tool can be started. To launch it, select "Demo Headboard Tuning" from the "Plug-ins" menu item (see Image #1):

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Usage

Lens Calibration is used to describe the process of generating lens shading correction (LSC) coefficients (see Image #2). The resulting settings can then be loaded in the EEPROM and/or stored in a file.

The Lens Calibration process is fully automated via the tooktool, but each step can be run individually if desired, but in most cases this is not necessary.

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The Color Uniformity indicator objectively evaluates the lens shading correction using a mathematical formula calibrated to human image quality perception. The lower the value, the better the image quality is. A value of 2.0 or less represents no loss of image quality. If the value is 2.0 or less then the indicator will be green. If the value is more than 2.0 but less than 3.0 the indicator will be yellow, and a value of 3.0 or more the indicator will be red. In those cases something may have gone wrong with the calibration and the source of the problem should be investigated. The problem area(s) will be highlighted with a red square. See Image #5 #4 for an example.

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Possible causes and resolutions of Color Uniformity failures are:

• Dust on the sensor; this will be indicated by one or several randomly situated red square. It may be possible to clean the sensor and run Lens Calibration again.
• The lens may be misaligned; this will be indicated by red squares situated on a single edge of the display.  In some cases the lens can be adjusted.
• Good Color Uniformity is less than value may be too low for the given sensor; this will be indicated by red squares covering most of the image. Note that a value of 2.00 is based on evaluation and measurement of human perception to image quality, so increasing this value may resolve the Color Uniformity error but will result in overall lower image quality.

Note:      The LSC setting will be saved to the EEPROM and the file regardless of the Color Uniformity result

Evaluate the LSC solution

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Another subjective method to evaluate the effectiveness of the LSC solution is to use the Analysis Graph.

• Display the Analysis Graph by selecting the Show Graph button.
• Set the Analysis Graph type by selecting Row from the "Mouse Selection" box, and then within the image display set the Analysis Graph location so it is in the center of the image.
• Select Cumulative Intensity in the Analysis Graph and observe that the displayed lines of red, green, and blue are flat and uniform (see Image

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• #3; "Analysis Graph").
• To observe what happens when LC is not enabled, select the Disable LC button. The Analysis Graph will now display lines that are uneven and non-uniform (see Image

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• #5).

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Name of file containing the LSC settings

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