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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, Figure 20) 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 (Figure 21). All SHIL calibration standards are found in drawer PP-2B.
- Set camera f/stop to 22 (Figure 22). 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 of the calibration section.
Figure 20: 3D standard with MacBeth Color standard.
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Calibration Check
The following three steps in Calibration Check are calibration check is designed for technicians to check the SHIL’s calibration. 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 Calibration section below.
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7. Select Open Test Image and select the image you just took (Figure 28-1), 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. - 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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3. Click JPEG Corrections tab (Figure 30-3). Adjust the Brightness, Contrast, and Gamma levels (Figure 54-4) to achieve a straight line in the Applied Corrections tab and the ROI Corrected box should have values near 250 for the white square (is this correct or should they be 235243). 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. (see JPEG corrections cheat sheet in SHIL lab notebook, to be added). The Applied Corrections Graph should be a straight line and the ROI Corrected Box should have values near 250. 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.
Figure 30: 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.
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2. In the IMS control panel select Motion and then Drive Disable from the dropdown menu (Figure 32). You will have to move the camera by hand for the calibration, disabling the motor allows manual movement of the camera on the track.
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3. In the IMS control panel click Instruments > JAI Camera Settings (Figure 33). The lights turn on automatically when the JAI Camera Setup window opens.
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1. Click the Gains-Black-Shade-Flat tab (Figure 36).
Figure 36: JAI Camera Setup Window showing the Gains-Black-Shade-Flat tab. The Gains-Black-Shade-Flat tab is outlined in red.
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2. Click the Clear All Gains, Clear Black Gains, Remove Pixel Black Correction, Remove Shading Correction, and Remove Pixel Gain Correction (Figure 3637). You will notice all values in the Master and Black gains go to zero.
Figure 3637: Remove the corrections and clear gains.
4. In Master Black field, enter 40. (Why? - to raise the sensitivity of the camera's sensors to pick up dark values?)
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Color Balancing is currently being done using the QP card 101 v4 gray scale card. The MacBeth Color standard cards on board have all been damaged by the LED lights, changing the RGB values ont he on the cards. The MacBeth Method is still retained in Color Balancing Camera - Old Method MacBeth Color Checker Card section below. We carry a large stock of QP card 101 on board. They are more heat resistant than the MacBeth card, and much cheaper to replace.
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1. Click the RATES and EXPOSURE tab (Figure 3738-2).
2. On the Green Lock control select OFF (Figure 3738-3). The RGB exposures are now adjustable.
3. Set the Line Trigger Interval until the Max Image Scan Speed is 10 (Figure 3738-4). Adjust values by clicking in the field and typing values or using the up and down arrow on the keyboard. The Line Trigger Value must be greater than the Exposure Intervals for red, green, and blue.
4. Move the camera carriage over the QP card 101 on the track.
5. Click Start Grab (Figure 3738-5).
6. Click Lights ON (Figure 3738-6). You should see the QP card 101 in the live grab window. Remember to only keep them the lights on for ~20 sec and then turn off for ~60 sec while preforming the following. You should see the QP card 101 in the live grab window.calibration.
7. Draw a green ROI box in the light gray (white) area. Now the Red, Green, and Blue values above the image grab window show the values inside your square. The RGB value of the QP card 101 v4 in the light gray (white) area is 235.
8. Adjust the Red, Green, and Blue Exposure times until each value in the live grab window is 235. Remember to turn off the lights regularly!
Figure 3738: Rates and Exposure tab with chronological steps on the screen.
Adjust Adjust Gains
Master gain changes the whites/high RGB values. You can use positive or negative values. Master black changes black/low RGB values. You can only input positive values for Master Black. Without changing the gain values, the SHIL gives you a raw image with too high of a contrast. That is, whites are too bright, and blacks are too dark. You need to adjust the mid-tone and black level to achieve a good calibration. To do this, it is recommended to at least raise the master black. Lowering the master gain will help achieve a more ideal mid-tone, but be careful, because color can start to lose saturation when you do.
1. Select Click the Gains-Black-Shade-Flat tab (Figure 3839)
2. Click Start Grab
3. Click Lights ON. Preform the following steps as quickly as possible. Try to do it in 20 sec intervals with 60 sec lights off break.
4. Draw the green ROI box on the darkest square of th QP card 101.
5. Adjust the Master Black value until the RGB values are ~40. Qualitatively, this is what's been found to produce a nice image. Please note that the RGB value of the QP card 101 card v4 for this square is 80, but this will be corrected for that value in the TIFF/JPEG correction. Remember to turn off the lights regularly!
6. You can also adjust the RedBlack, BlueBlack, RedGain and BlueGain values to adjust those specific channels. Keep an eye on the histogram graph on the bottom left corner. We want all the colors to overlay each other pretty closely.7. Adjusting the RedGain and BlueGain will move the colors (histographs) in the graph in the lower left, move until they are over lapping.
7. Adjusting the gain likely changed the RGB gain likely changed the RGB values in the light gray card. Draw an ROI box in the light gray (white) square. If the values aren't 235 go back to the Rates and Exposure tab and adjust the the values until you hit 235. Check back in the dark gray square and see its still ~40, adjust the gains to obtain RGB of ~40. This is a balancing act and can be tideous.
8. When the light grey (white) and the dark grey are well balanced you can move on to applying corrections. How long the lights have been will affect the color balance. If the lights have gotten quite warm and everything looks even, then when the lights are 'cold' the blue channel will be lower than the others.
9. Click Lights OFF
Figure ##39: Adjusting Gainsmaster black of the darkest patch to obtain RGB values of ~40.
Apply Corrections
We apply three corrections Pixel Black, Shading and Pixel Gain. Only do the corrections after you have finished adjusting the RGB exposure and Gain.
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1. Assure the lights are off
2. Take the lens cap (Fig. 33Figure 40) and place on lens (Fig. 34Figure 41). The lens cap is located in drawer PP-2B.
Figure 33 40: Lens cap for the camera
Figure 34 41: Lens Cap being put on camera
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3. Click Pixel Black Auto Correction. The RGB lines in the Profile graph should be uniform (Fig. 35Figure 42).
4. Remove lens cap when finished.
Figure 3542: Grab and Profile after the Pixel Black Correction applied.
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1. Take the silicone heat resistant gray mat and clean off any dust with a piece of tape (Fig. 36Figure 43)
2. Place the heat resistant gray silicone mat on the bench on top of the QP card 101, or anywhere along the bench, make sure that it is level and perpendicular to the camera’s axis.
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4. Defocus the lens on the camera just a little bit (Fig. 36Figure 44). Look at the Profile graph and slightly rotate the lens’ focus until the RGB lines are smoother, but still have some variation.
Figure 3643: The Gray silicone mat being cleaned with tape.
Figure 3644: The lens being unfocused.
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5. The RGB lines should appear “bowed” evenly across profile and centered in the image (Figure 45). If not check the orientation of the gray mat, it needs to be flat and perindicular perpendicular to the camera. This very important!
Figure 3745: Grayscale card corresponding RGB Profile visible.
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 (Fig. 38Figure 46).
Figure 3846: Image grab and profile after the Shading Correction has been applied.
7. Click Lights OFF and wait 60 , at least, 60 sec before proceeding.
Pixel Gain Correction
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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 (Fig. 39Figure 47).
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47: Grab and Profile after the Pixel Gain Correction has been applied.
3. Remove the gray mat and use the QP card 101 to refocus the lens. Move Camera over the mm increments and focus the lens by turning it manually.
4. Click Lights Off. (at this point I wait 60 secs for lights to cool turn lights back on and check the light gray (white square) RGB values again and adjust the exposure intervals if needed)
4. Click Save. The lights will turn off and the window closes.
5. In the IMS Control panal panel click Motion and then Drive Enable (Figure 48). This allows the software to control the camera movement.
Figure 4048: Drive enable control highlighted.
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1. Place the 3D calibration standard on track as shown (Fig. ##Figure 49). The color squares must be oriented as pictured below, butted against the red reflection bar.
Figure 20 49: Color standard in track in correct orientation.
2. Open IMS and Click Start.
3. Scan the STND Color barcod label (Fig. ##bFigure 50b). Check the ColorChecker Standard box (Fig. ##aFigure 50a). 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.
4. Click Take A Picture.
5. When the image has finished click Crop and then Save. We use the uncropped image so the crop here is not important.
Figure 50: a) sample information screen with ColorChecker box checked, b) standard barcode being scanned.
6. On the main IMS panel click select Instruments and Camera: Image Correction (Fig. 22Figure 51).
Figure 2251: Image Correction command selection.
The main Image Correction window
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displays three main areas
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A. Graph panel: Main graphical viewing area on the left side of the screen.
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Applied Corrections Tab: Applies polynomial fit corrections to the RGB lines.
B. Image Viewing Panels: Area in upper right portion of the screen that displays the original and corrected test image and color checker with RGB values.
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Color Checker: Displays the known values of the MacBeth 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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Instructions: Shows instructions to follow in this window.
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7. Select Open Test Image and select the image you just took (Fig. 23Figure 52-1), files found 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. - 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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8. Draw a ROI box loosely around the color checker in the Original box (Figure 52-2)
9. Click Crop (Figure 52-3).
10as illustrated above, then click Crop. Draw another ROI box around the Color Checker squares and this time making sure to only have MacBeth colorchecker 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.
Figure 52: Image Correction Window. Steps are indicated in the figure.
Tiff Correction
1. Click TIFF Correction Mode (Figure 53-2)
2. Click Uncorrected Image tab. This graph shows the measured red, green, and blue values of the gray scale color squares (Figure 53-3).
3. Click TIFF Correction tab to adjust the shape of the graph. The goal is to have line as straight as possible (Figure 53-4).
4. In the Tiff Correction tab adjust the LUT polynomial order values for the Red, Green, and Blue channels (Figure 53-5). Adjust these values to create the lowest residual error with the smoothest curve in the Uncorrected Image tab. Values should be around 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 White Balance by Shutter Correction in the Calibration section belowabove. (see TIFF corrections cheat sheet in SHIL lab notebook, to be added).
Figure ##53: 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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Situations may 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. To apply a JPEG Correction follow the steps below:
1. Click JPEG Correction Mode Mode (Figure 54-1)
2. Click Applied Corrections tab (Figure 54-2)
3. Click JPEG Corrections tab (Figure 54-3). Adjust the Brightness, Contrast, and Gamma levels (Figure 54-4) to achieve a straight line in the Applied Corrections tab and the ROI Corrected box should have values near 250 for the white square (is this correct or should they be 235243). 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. (see JPEG corrections cheat sheet in SHIL lab notebook, to be added). The Applied Corrections Graph should be a straight line and the ROI Corrected Box should have values near 250. 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.
Figure 2554: 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.
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