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Prepare the scan to assess the current Image Correction values. If you can achieve a good image by either adjusting, or better yet, keeping the same, values in the following steps you will not need to adjust any of the camera settings in the JAI Camera Set-up window in the calibration instructions below.
NOTE: The Image Correction screen has been updated as of . We are in discussion with Lab Working Group on utilizing the new user interface. The main difference is that we can use colors other than the white, shades of grey and black to determine corrections. 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 an Image
1. Place the 3D calibration standard on track as shown (Figure 10). Be sure to use the XRite Color checker 2019. The color squares must be oriented as pictured below, butted against the red reflection bar.
Figure 10. Color standard in track in correct orientation.
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Figure 12. Image Correction command selection.
NOTE: The Image Correction screen has been updated as of . We are in discussion with Lab Working Group on utilizing the new user interface. The main difference is that we can use colors other than the white, shades of grey and black to determine corrections. 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.
The main Image Correction window displays three main areas (Figure 13):
main Image Correction window displays three main areas (Figure 13):
A. Graph panel: Main graphical viewing area on the left A. Graph panel: Main graphical viewing area on the left side of the screen.
Uncorrected Image Tab: Shows the measured red, green, and blue values of the gray scale color squares.
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Compare: Shows a visual and RGB values of the Original color square before corrections, the Xrite Color checker standard and of the Color color after corrections are applied.
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Figure 14. Image Correction Window. Steps are indicated in the figure.
Check TIFF and JPEG Corrections
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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. An enhance method (utilizing more colors in the write color cehecker) is being implemented , and the following steps are being updated (in progress)
The Image Correction screen has been updated as of . This is in discussion 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. 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 13):
A. Graph panel: Main graphical viewing area on the left side of the screen.
Uncorrected Image Tab: Shows the measured Redred, green, and blue values of the gray scale color squares.
Applied Corrections Tab: Applies polynomial fit corrections to the RGB lines.
Compare: Shows a visual and RGB values of the Original color square before corrections, the Xrite Color checker standard and of the color after corrections are applied.
B. Image Viewing Panels: Area in upper right portion of the screen that displays the original and corrected test image and Xrite color checker with RGB values.
Original: Displays the uploaded tiff.
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Color Checker: Displays the known values of the MacBeth Xrite Color Checker values.
C. Correction Panel: Panel in the lower right portion of the screen that allows user to apply corrections to the image
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JPEG Correction: Shows brightness, contrast, and gamma settings.
Instructions: Shows instructions to follow in this window.
Figure 13: Image Correction window.
7. On opening of the Image correction window the program prompts you to select the TIFF file of the color standard you took7. Select Open Test Image and select the image you just took (Figure 37-1), located in C:/DATA/IN/IMAGE. It does not matter if the JPEG or TIFF file is loaded. 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 3714-21)
9. Click Crop (Figure 3714-32).
10. Draw another ROI box around the Color Checker squares and this time making sure to only have XRite MacBeth colorchecker 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.
Figure37. Image Correction Window. Steps are indicated in the figure. New values for Color checker Values, RGB = 242, 242, 236)
Tiff Correction
11. Click the colors you want to sue for the correction curve. As of use only the white, shades of grey and the black.
Figure 14. Image Correction Window.
Check TIFF and JPEG Corrections
Here we check and adjust, if needed, our TIFF and JPEG Corrections. You may find you only need to slightly tweak the values and the calibration is good. With the new lights we have found that no adjustments have been needed. However if the image appears streaky, a physical change has happened to the Camera or lights, the RGB values between corrected and expected are far off (>10), or the graphs of either the tiff or jpeg don't look good, you will need to re-calibrate following the full calibration discussed below.
TIFF Correction Check
1. Click TIFF Correction tab (Figure 15-1).1. Click TIFF Correction Mode (Figure 38-2)
2. Click Uncorrected Image tab. This graph shows the measured red, green, and blue values of the gray scale color squares (Figure 38-3).
3. Click TIFF Correction tab to adjust the shape of the graph. The goal is to have line as straight as possible (Figure 38-4).4. In the Tiff Correction tab adjust the LUT polynomial order values for the Red, Green, and Blue channels (Figure 3815-51). Adjust these values to create the lowest residual error with the smoothest curve in the Uncorrected Image tab. Values Polynomial values should be around 4. Make about 3. Make sure that the curve does not wave about too much. If it does, the order values need to be lowered. Also check that the corrected ROI and MacBeth values should be Xrite color checker values are very close. Make sure that the white does not exceed the MacBeth value Xrite values (RGB = 242, 242, 236). If you are unable to produce a reasonable correction curve, it is necessary to redo your White Balance by Shutter Correction white balance correction in the Calibration section abovebelow.
Figure 15. Tiff Correction Figure 38. Steps for Tiff Correction illustrated on image. 1. Redraw box on color squares. 2. Select Tiff Correction Mode. 3. Put graph on Uncorrected Image. 4. Select Tiff Correction to view polynomial order. 5. Adjust polynomial order. 6. Check graph for linear relationship.
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
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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 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
JPEG Correction
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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.
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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).
1. Click JPEG Correction tab (Figure 17-1)
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1. Click JPEG Correction Mode (Figure 39-1)
2. Click Applied Corrections tab (Figure 39-2)
3. Click JPEG Corrections tab (Figure 39-3). Adjust the Brightness, Contrast, and Gamma levels (Figure 39-417) to achieve a straight line in the Applied Corrections tab and the ROI Corrected box should RGB Corrected values in the Compare tab should have values near 242 for the white square . We 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 242. The BCG 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.
Figure 39. Steps for JPEG Correction illustrated on image. 1. Select JPEG Correction Mode. 2. Select Applied Corrections tab on graph. 3. Select JPEG Correction to see Brightness, Contrast, and Gamma Corrections. 4. Adjust Brightness, Contrast, and Gamma corrections. 6. Check graph for Linear Relationship. 7. Check the boxes in the Color Checker and compare to RGB values in corrected image.
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 4. If the values all look 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 is complete. 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.
d) Check on Calibrated Computer
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