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2. With lights off click Pixel Black Auto Correction. The RGB lines in the Profile graph should be uniform (Figure 28).
3. Remove lens cap when finished.
Figure 28. Pixel Black Correction applied.
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Figure 29. The Gray silicone mat being cleaned with tape.
5. The RGB lines should first appear “bowed” evenly across profile and centered in the image (Figure 30). If not check the orientation of the gray mat, it needs to be flat and perpendicular to the camera. This very important. A wooden holder was designed to hold the mat, it should be in the SHIL calibration drawer.
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6. Click the Shading Correction - Flat Method button. This can take a few seconds, don’t click anything else until it is done. The RGB lines should now be flat (Figure 31).
Figure 31. Image grab and profile after the Shading Correction has been applied (NEED NEW IMAGE).
7. Click Lights OFF and wait for temperature to decrease below 35 °C.
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2. Click the Pixel Gain Correction - Flat Method button and move the camera very slowly back and forth. This averages the pixels and helps eliminate streaking in the image. This will take several seconds, don’t click anything else until it is done. When its done the RGB lines should still be flat and the individual RGB the same, but may not be equal to each other (Figure 32).
Figure 32. Grab and Profile after the Pixel Gain Correction has been applied.
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Note: this section follows the same steps as listed in the Calibration Check section above. This needs to be completed after a Calibration. Refer to Section
The Image Correction screen has been updated as of . This is in discussion being discussed with Lab Working Group on utilizing other colors for calibration. The main difference is that we can use colors other than the white, shades of grey and black to determine corrections. . The new interface allows the user to calibrate (image correct) with other colors on the Xrite color checker and provides a visual display of the colors calculated by the RGB values of the Xrite color checker and the corrected color. For now, continue to select the white, shades of greys and black for image correction calibrations. This user guide needs to be updated to reflect the new user interface. In progress.
Take New Picture
1. Place the 3D calibration standard on track as shown (Figure 34). The color squares must be oriented as pictured below, butted against the red reflection bar.
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The main Image Correction window displays three main areas (Figure 1337):
A. Graph panel: Main graphical viewing area on the left side of the screen.
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JPEG Correction: Shows brightness, contrast, and gamma settings.
Figure 1337: Image Correction windowuser interface.
7. On opening of the Image correction window the program prompts you to select the TIFF file of the color standard you took. The image loads into both the Original and Corrected windows.
8. Draw a ROI box loosely around the color checker in the Original box (Figure 1438-1)
9. Click Crop (Figure 1438-2).
10. Draw another ROI box around the Color Checker squares and this time making sure to only have XRite MacBeth color checker in the box. White squares will appear inside each square. Adjust the box to get those white squares close to the center of the color squares. Do not click Crop again.
11. Click the colors you want to sue use for the correction curve (Figure 38-3). As of use only the white, shades of grey and the black.
Figure 1438. Image Correction Window.
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1. Click TIFF Correction tab (Figure 1539-1).
2. Click Uncorrected Image tab. This graph shows the measured red, green, and blue values of the color squares.
3. In the Tiff Correction tab adjust the LUT polynomial order values for the Red, Green, and Blue channels (Figure 1539-1). Adjust these values to create the lowest residual error with the smoothest curve in the Uncorrected Image tab. Polynomial values should be about 3. Make sure that the curve does not wave about too much. If it does, the values need to be lowered. Also
4. In the Compare tab check that the corrected ROI color square and Xrite color checker RGB values are very close (Figure 40). Make sure that the white does not exceed the Xrite values (RGB = 242, 242, 236). There is also a visual display so you can see the difference in color for the color checker and the corrected. If you are unable to produce a reasonable correction curve, it is necessary to redo your white balance correction described in the the Calibration section below.
Figure 1539. Tiff Correction
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 1741-1).
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 in value to the RGB of the Color checker RGB values.
Figure 1640. Use the Compare tab to view the RGB values for the Xrite color checker and the corrected.
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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 1741).
1. Click JPEG Correction tab (Figure 1741-1)
2. Adjust the Brightness, Contrast, and Gamma levels (Figure 1741-1) 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 box for the color selected (Figure 41-2, 41-3) should have values near the RGB values of 242, 242, 236the Color Checker STND. 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 have to redo the following Calibration section and complete the calibration instructions listed in the Calibration section belowCalibration instructions.
Figure 1741. 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.
d) Check on Calibrated Computer
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