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The laboratory technician calibrates the system when needed by adjusting camera settings and analyzing an imaged QP 101 V4 Color Standard. The current light system obtains nearly uniform illumination intensity from the core’s surface (half or whole round) to the bottom of the liner by a combination of high intensity, overlapping large diameter light source, close coupling to the imaged surface and the “line” image plane. The bottom edge of the brass led mount should be set between 2 and 4cm from the image surface. For uneven hard rock cores the height can be set higher but illumination intensity will drop, exposure times lengthen, f-stop opened and scanning speed reduced. Note, any height change to the lights requires re-calibration. Heat is removed from the LEDs and transferred to the surrounding air via the copper heat pipes. While these to get hot they are not a burn hazard. However they are very delicate and bend at the slightest touch, so use care when working with the camera lens. For more detailed information on the theory behind the calibration please refer to the Advanced SHIL Calibration (in developementdevelopment).
Note: the following instructions are devided into 2 sections. Calibration Check and Calibration.
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8. Draw a ROI box loosely around the color checker in the Original box as illustrated above, then click Crop. Draw another ROI box around the Color Checker squares and this time making sure to only have squares 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.
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The main Image Correction window displays three main areas (Fig. ##):
A. Graph panel: Main graphical viewing area on the left side of the screen.
Uncorrected Tab: Shows the measured Red, green, and blue values of the gray scale color squares.
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.
Original: Displays the uploaded tiff.
Corrected: Displays the uploaded tiff with corrections applied.
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
TIFF Correction: Shows tiff red, green, and blue polynomial fit.
JPEG Correction: Shows brightness, contrast, and gamma settings.
Instructions: Shows instructions to follow in this window.
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3. Click TIFF Correction tab to adjust the shape of the graph. The goal is to have line as straight as possible.
4. Adjust In the Tiff Correction tab adjust the LUT polynomial order values for the Red, Green, and Blue polynomial orderschannels. Adjust these values to create the lowest residual 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 Calibration section below. (see TIFF corrections cheat sheet in SHIL lab notebook, to be added).
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Figure ##: 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 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).
JPEG Correction Check (Fig.##)
In JPEG correction you will check and adjust if necessary the brightness, contrast and gamma (BCG) of the image.
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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.
1. Click JPEG Correction Mode
2. Click Applied Corrections tab
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Calibration (JAI Camera Setup and Image Corrections)
Camera and Track Setup
1. Confirm the camera F-stop is set to 22 (Fig. ##). 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. See the Advanced SHIL Calibration (in developement) for further information on F-stop.
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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 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.
Adjust Exposure (Achieving White Balance by Shutter Correction)
The aim of white balance is to correct the LED's lighting with the Red, Green and Blue sensor's sensitivity to produce neutral values for the QP card 101. The exposure intervals we set relate to how long the camera can pick up values for each color band. Try not to keep the lights on for longer than ~ 20 sec and then keep them off for ~60 sec. As the lights warm up the RGB values change, particularly the blue value, and change most rapidly in the first minute of the lights warming up. Since the SHIL is often used after being off for a bit, we are trying to calibrate to represent the measuring conditions, as best we can. Right now we do not have a defined procedure for keeping the lights on/off during calibration and thus suggest 20 sec intervals.
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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!
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.
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Figure ##: Adjusting Gains.
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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After discussion with JAI we learned the order of corrections should be Pixel Black, Shading, and Pixel Gain. Previously our order was Shading, Pixel Gain, and Pixel Black. The order has been updated here. We were also to told to do all exposure and gain adjustments before doing these three camera corrections. This manual has been updated to reflect those changes.
Pixel Black Auto Correction
1. Assure the lights are off
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Figure 35: Grab and Profile after the Pixel Black Correction applied.
Shading Correction
1. Take the silicone heat resistant gray mat and clean off any dust with a piece of tape (Fig. 36)
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3. Click Lights On, and move the camera over the gray mat.
4. Unfocus Defocus the lens on the camera just a little bit (Fig. 36). Look at the Profile graph and slightly rotate the lens’ focus until the RGB lines are smoother, but still have some variation.
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7. Click Lights OFF and wait 60 sec before proceeedingproceeding.
Pixel Gain Correction
1. The camera’s lens should still be de-focused. Make sure gray silicone mat is flat
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4. Click Save. The lights will turn off and the window closes.
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5. In the IMS Control panal click Motion and then Drive Enable. This allows the software to control the camera movement.
Figure 40: Drive enable control highlighted.
Image Corrections
Note: this is section follows the same proceedure steps as listed in the Calibration Check section above.
Take New Picture
1. Go to Motion > Drive Enable, to re-enable the motor (Figure 40).
Figure 40: Drive enable control highlighted.
2. Go to IMS Main Panel Select DAQ > Image Capture Motion Setup (Figure 41). In this window confirm that speed is set lower than the speed calculated by the Line Trigger Interval
Figure 41: Image Scan Setup Window.
3. Click Start
Place the 3D calibration standard on track as shown (Fig. ##). The color squares must be oriented as pictured below, butted against the red reflection bar.
Figure 20: Color standard in track in correct orientation.
2. Open IMS and Click Start.
3. Scan the STND Color label (Fig. ##b4. Scan the STND Color label on the aluminum track behind the monitor (Figure 42). 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 42 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 user use the uncropped image so the crop here is not important.
76. On the main IMS panel select click Instruments and Camera: Image Correction (Figure 43Fig. 22).
Figure 4322: Image Correction command selection.
8. The main window opens. On the right side of the screen select Open Test Image . Open the image just taken (Figure 44). It has been mentioned that it doesn't matter if you load in the jpeg or tiff, not tested yet
Figure 44: Open Test Image Window with all images displayed.
Tiff Correction
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Correction window opens (
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Fig. 45). Note the three main areas in the window:
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Figure 45: Image Correction Window.
A. Graph panel: Main graphical viewing area on the left side of the screen.
Uncorrected Tab: Shows the measured Red, green, and blue values of the gray scale color squares.
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.
Original: Displays the uploaded tiff.
Corrected: Displays the uploaded tiff with corrections applied.
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
TIFF Correction: Shows tiff red, green, and blue polynomial fit.
JPEG Correction: Shows brightness, contrast, and gamma settings.
Instructions: Shows instructions to follow in this window.
Figure 45: Image Correction Window.
1.Make sure TIFF Correction Mode is selected in the upper right corner and the TIFF Corrections tab is selected in the bottom right corner (Figure 46).
Figure 46: Tiff correction Mode button and Tiff Correction tab both highlighted in red.
2. In the ORIGINAL image control create a selection rectangle (right-click drag) of the MacBeth card and click CROP (Figure 47). Repeat as necessary until the card fills the entire image.
Figure 47: Green crop square drawn around the color squares.
3. Again create another selection rectangle over the image but do not release the mouse. Move the lower corner of the rectangle until small white boxes appear over the color squares. Make sure the boxes are in the center of the squares. Release the mouse. The pixels in the squares will be averaged and used for the RGB values in the calibration (Figure 48). (not quite how it works right now, white squares don't show up until mouse is released, error reported in confluence).
Figure 48: 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.
7. Select Open Test Image and select the image you just took (Fig. 23-1), files found 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.
Figure ##: Image Correction Window. Steps are indicated in the figure.
8. Draw a ROI box loosely around the color checker in the Original box as 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.
Tiff Correction
1. Click 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. In the Tiff Correction tab adjust the LUT polynomial order values for the Red, Green, and Blue 4. Look in the TIFF Correction tab and set the LUT polynomial order values for the RGB channels. Adjust these values to create the lowest residual error with the smoothest curve in the UNCORRECTED image Uncorrected Image tab. Should Values should be around 4. Make sure that the curve does not wave about if . If it does the order values need to be lowered. Also check 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 may be necessary to redo your white balance correction and start over.
This correction is applied to both the TIFF and JPEG image but for the JPEG image you can also apply a Brightness, Contrast and Gamma correction. This is done at the photographer’s discretion. With better balanced leds on the new light system I did not use the correction and left the values at their mid-points.
JPEG Correction
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. Select JPEG Correction Mode (Figure 49).
. 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 Calibration section below. (see TIFF corrections cheat sheet in SHIL lab notebook, to be added).
Figure ##: 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 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).
JPEG Correction
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
2. Click Applied Corrections tab
3. Click JPEG Corrections tab. Adjust the Brightness, Contrast, and Gamma levels 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 235). 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 25Figure 49: 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.
24. In the BCG Correction Window, select JPEG Correction. Adjust the Brightness, Contrast, and Gamma Settings. The Corrected color squares will update as the settings are changed. 3. 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. 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. Calibration is complete.
Camera Height Adjustment
- Move the camera so it is just on the edge of the grayscale card at the end on the tray. On this card are mm and cm marks on the edge.
- Click the GRAB button and watch the image as you make slow camera position adjustments until the centimeter lines show up on the image graph as sharp spikes.
- The graph as two cursors, use the mouse and drag one cursor aligning it with the spike. Take the second cursor and do the same with an adjacent spike. Just above the Profile graph there is a control labelled Pixel Delta this value should be between 198 and 202 pixels. If not, adjust the camera (not lights up and down refocusing after every move until you get within the range. Warning this can be very tedious!
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