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- Color Standard values vary based on the standard and the manufacturer of the standard. Verify the values of the MacBeth Color Standard (multi color squares on the 3D standard, Fig ##) before starting (How do we do this?). Check the grayscale card to determine what the percentage of gray. The target calibration values will vary based on the percentage of gray because the target values depend on the percent grayscale card. Max RGB value is 255. If using a 50% grayscale card, target red and green value is 127, a 25% grayscale card target value is 64, etc. For our QP 101 v4 card, the RGB values are 235, 111, and 80 (Fig. ##). All SHIL calibration standards are found in drawer PP-2B.
- Set camera f/stop to 22 (this 16Fig. ##). F/22 is preferred for standard scanning with the current light set up; F/16 is also acceptable. For hard rock cruises, where 360°whole round scanning is required, a larger F/stop number is required.
- If you haven’t set the camera’s height, now is the time to do so! See the section Camera Height Adjustment at the end.
Check Calibration
The first step of calibrating is to see if you actually need to by taking an image of the color standard and comparing the observed RGB values and comparing with the expected RGB values.
Take an Image
1. Grab the calibration standard and remove from liner (Figure 19). Calibration Standard is located in drawer PP-2B.
Figure 19: The calibration standard in its cover.
Figure ##: 3D standard with MacBeth Color standard.
Figure ##: QP card 101 v4 grey scale standard.
Figure ##: Setting the F Stop on the Camera.
Calibration Check
The following steps are designed for technicians to check the SHIL’s calibration and to determine if it needs to be adjusted. The calibration check is required to be done at the start of every expedition prior to receiving the first core. If adjustments to the calibration are needed, please see the full SHIL Calibration below.
Step 1: Determine the scan rate for the expedition
1. Talk to your science party to determine what scanning parameters (scan rate) they wish to use. A typically scan rate has been between 8-10 cm per second. Note, with the new, brighter LED lighting system, faster scan rates can be achieved compared to expeditions prior to Expedition 390C.
2. Compare the current scan rate to the requested rate.
a. Launch ‘IMS’ on the SHIL computer, click on the ‘DAQ’ tab and open the Image Capture Motion Setup window.
b. The speed (Fig. ##) of the camera will be in the first box. If the values need to be changed to match the requested values by the science party, please proceed to the full SHIL Calibration guide below as you will need to do a full calibration. If the values match, close the ‘Image Scan Setup’ window and proceed with the following checks.
Figure ##: Checking the Image Scan Speed.
3. Check the trigger interval rate to see if the values are suitable for the scan rate.
- Click on Instruments and open the JAI Camera Set-up window.
- Turn the lights off IMMEDIATLY by clicking Lights OFF (Fig. ##). Remember the lights produce a lot of heat and can cause damage to anything underneath them if they remain stationary for too long.
- Click Rates and Exposure tab (Fig. ##)
- Check that the Max Image Scan Speed is equal to, or slightly less than the designated Scan Rate.
- Again, if the values need to be changed to match the requested values by the science party, please proceed to the full SHIL Calibration below. If the values match, close the JAI Camera Set-up window and proceed.
Figure ##: Checking the Max Image Scan Speed.
Step 2: Assess the SHIL scan
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 full SHIL Calibration.
Take an Image
1. Place the 3D calibration standard on track as shown (Fig. ##). The color squares must be oriented as pictured below, butted against the red reflection bar2. Put the Calibration Standard in the track (Figure 20). The color square must be oriented as pictured below.
Figure 20: Color standard in track in correct orientation.
32. Open IMS and Click Start.
43. Scan the STND Color label on the aluminum track behind the monitor (Figure 21(Fig. ##b). Check the ColorChecker Standard box (Fig. ##a). With this box selected no corrections are applied to the image so we are able to assess the raw image quality.
Figure 21: Left, sample information screen with ColorChecker box checked. Right, standard barcode being scanned.
54. Click Take A Picture.
65. When the image has finished click Crop and then Save. We use the uncropped image so the crop here is not important.
76. On the main IMS panel select Instruments and Camera: Image Correction (Figure Fig. 22).
Figure 22: Image Correction command selection.
87. Select Open Test Image and select the image you just took (Figure Fig. 23-1), 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. - at this point not tested to confirm it doesn't matter if a jpeg is loaded and used to perform the tiff correction.
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Figure 23: Image Correction Window. Steps are indicated in the screen. 1. Open the Scan 2. Draw a box around ColorChecker Squares 3. Click Crop.the screen.
8. Draw a ROI 9. The image loads into both the Original and Corrected windows. With the rectangular box selected, draw a box loosely around the color checker card in the Original box as illustrated above, then click Crop. Draw a another ROI box around the Color Checker squares again and this time making sure to only have squares in the box. This time white 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.
Step 3: Check TIFF and JPEG Corrections
Here we check and can adjust our TIFF and JPEG Corrections. You may find you only need to slightly tweak the values and the calibration is good. 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, or the graphs of either the tiff or jpeg don't look good, you will need to recalibrate.
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re-calibrate following the full calibration discussed below. For more detail on the graphs and values in the Image Correction window please see Create Correction Curve section below.
TIFF Correction (Fig. ##)
1. Select TIFF Correction Mode
2. Click Uncorrected Image tab. This graph shows the measured red, green, and blue values of the gray scale color squares.
3. Click TIFF Correction tab to adjust the shape of the graph. The goal is to have line as straight as possible.
4. Adjust the Red, Green, and Blue polynomial orders to
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create the lowest residual
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error with the smoothest curve in the UNCORRECTED IMAGE tab. Values should be around 3 or 4. Make sure that the curve does not wave about. If it does the order values need to be lowered. Also check that the corrected ROI and MacBeth values should be very close. Make sure that the white does not exceed the MacBeth value. If you are unable to produce a reasonable correction curve, it is necessary to redo your white balance correction in the full Calibration discussed below. (see TIFF corrections cheat sheet in SHIL lab notebook).
Figure 24: 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.
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