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Note: the TIFF correction is applied to both the TIFF and JPEG image but for the JPEG image you can also apply a Brightness, Contrast and Gamma (BCG) correction (See JPEG Correction section below). This is done at the photographer’s discretion. With better balanced LEDs on the new light system you may not have to use the BCG corrections (leave the values at their mid-points. Figure 17-1).
4. Compare the original, the color checker RGB values and the Corrected RGB values for each color square . (Figure 16). There is also a visual so you can see the difference in color for the color checker and the corrected. The RGB values for the corrected should be very close (<5) in value to the RGB of the Color checker RGB values.
Figure 16. Use the Compare tab to view the RGB values for the Xrite color checker and the corrected.
JPEG Correction Check
In JPEG correction you will check and adjust, if necessary, the brightness, contrast and gamma (BCG) of the image. Situations may also arise where a JPEG correction should be applied. In the instance of very white or very dark cores, the TIFF images may look good but the JPEG images may look washed out or too dark to view details. JPEG corrections do not alter TIFF image settings. As mentioned above, with the new lights the BCG values may not need to be adjusted and to be kept at the mid values (Figure 17).
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2. Adjust the Brightness, Contrast, and Gamma levels (Figure 17-4) to achieve a straight line in the Applied Corrections tab and the RGB Corrected values in the Compare tab should have values near 242 for the white square and near 50 for the black. We want a linear relationship between the measured and given values. Each BCG setting adjusts the line in different ways and there are many different ways to adjust the values to achieve a linear relationship. You want to achieve a good image with good brightness, where the image has good saturation and not too washed out. The Applied Corrections Graph should be a straight line and the ROI Corrected Box should have values near the RGB values of 242, 242, 236. These may change depending on the instance of extreme colors, extremely white or extremely dark cores, in which the settings may have be tweaked more to get a user friendly consumer image.
3. If the values are good and there are no streaking issues in the images or other unwanted artifacts, you can click Save and no further adjustments are needed. However if you have determined the doesn't look good, click Cancel and you can proceed to the following section and complete the calibration instructions listed in the Calibration section below.
Figure 17. JPEG Correction using Brightness, Contrast and Gamma. It is helpful to note that with the current light set up we have not had to adjust those values to obtain a good image.
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