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Figure 30: Lens Cap being put on camera
3. Click the Pixel Black Auto Correction. The RGB lines in the Profile graph should be uniform (Figure 31). (Note: half the time a separate window window pops up to confirm lens cap is on, then user clicks 'Proceed' to apply correction. Inconsistency reported in Confluence)
Figure 31: Grab and Profile after the Pixel Black Correction applied.
Color Balancing the Camera
1.Make sure the lens is focused. To focus the camera the lights need to be on and the camera over the section grayscale card or calibration card.
2. Grab the calibration standard and remove from liner (Figure 32). Calibration Standard is located in drawer PP-2B.
Figure 32: The calibration standard in its cover.
3. Put the Calibration Standard in the track (Figure 33). The color square must be oriented as pictured below.
Figure 33: Color standard in track in correct orientation.
4. Select the tab RATES and EXPOSURE (Figure 34).
Figure 34: Rates and Exposure window, the tab is highlighted in red.
5. On the Green Lock control select OFF (Figure 35). The other exposures are now adjustable.
Figure 35: Green Lock control highlighted in red and set to off.
6. Set the Line Trigger Interval until the Max Image Scan Speed is 8 for now. Adjust values by clicking in the field and typing values. We’ll come back to this value later.
7. Turn on lights.
8. Click the Start Grab (Figure 36).
Figure 36: Start Grab button highlighted in red.
9. Move the camera over the Macbeth color standard until you see the white, dark blue, orange and brown color bars in the image. Place the cursor in the white square, right-click and draw a rectangle by dragging diagonally. Release the mouse when you have select most of the white bar. The rectangle (marked in green) should only have the white color and nothing else inside (Figure 37).
Figure 37: The grab window is highlighted in red. A green square is drawn in the white color square of the appropriate row.
10. Above the image you will see controls for the average RED, GREEN and BLUE values for all of the pixels within the rectangle. You will also see the ratio values for RED/GREEN and GREEN/BLUE.
11. Adjust the Red Exposure value until the RED value is 245.
12. Adjust the Green Exposure value until the RED/GREEN value is 1.
13. Adjust the Blue Exposure value until the GREEN/BLUE value is 1. Congratulations you just White Balance the upper limit of the camera, but you are not done.
14. Select the tab GAINS-BLACK-SHADE-FLAT and do the following:
15. Move the camera over the Macbeth color standard until you see the black, blue, gold and cyan color bars in the image. Place the cursor in the black square, right-click and draw a rectangle by dragging diagonally. Release the mouse when you have select most of the black bar.
16. Adjust the Master Black gain until the GREEN value is around 15.
17. Adjust the Red Black gain until the RED/GREEN value is 1.
18. Adjust the Blue Black gain until the GREEN/BLUE value is 1.
Setting the Line Rate
The rules:
- Exposure intervals for the Red, Green and Blue channels is a function of the light intensity of the LEDs.
- Led intensity for the three channels is a function of the LED spectrum. Cold lights 65K are very blue while warm lights 55k are reddish. Neutral light is preferred where RGB are nearly equal but all leds are variable. Generally red is the lowest intensity and will require the longest exposure time. That is why in the above procedure we start with red, but you should always start with lowest intensity channel.
- Intensity is also a function of the F-stop. The smallest F-Top is preferred because it gives the greatest depth of focus but also lowers the intensity.
- Intensity is also a function of how closely coupled the lights are to the core surface but for practical reasons we need to keep a minimum clearance for safe operations.
- Don’t forget to check that all of the lights are evenly illuminated or even on. One led can fail without affecting these other. Don’t ever look at the leds directly!
- Line rate must be greater (20us) than the red, green and blue exposure rates set in the above procedure.
- The shorter the line rates the faster the image can be scanned.
- If you move the track faster than the scan rate you will see dropped lies in your image.
So you must balance all of these setting to obtain the best scanning rate. That means the above White balance procedure described above may have to be repeated as you adjust light position, f-stop etcetera.
Note: when you adjust the Line Rate interval it will automatically adjust the speed of the track to a scan speed that will not cause dropped lines. You can override this value in the Motion Control Setup …be careful.
Create Correction Curve
1.Click the Save button and leave the JAI Camera Utility.
2. Go to Motion > Drive Enable, to re-enable the motor (Figure 38).
Figure 38: Drive enable control highighted.
3. Go to IMS Main Panel Select DAQ > Image Capture Motion Setup (Figure 39). In this window confirm that speed is set lower than the speed calculated by the Line Trigger Interval
Figure 39: Image Scan Setup Window.
4. Click Start. Scan the STND Color label on the aluminum track behind the monitor (Figure 40).
Figure 40: Standard barcode.
5. Check the Color Checker Standard box (Figure 41). This does not apply a correction to image.
Figure 41: ColorChecker Standard Box highlighted in red.
6. In the main IMS window click on Instuments and select IMAGE Correction (Figure 42).
Figure 42: Image Correction selection highlighted.
7. The main Image Correction window opens (Figure 43). Note the three main areas in the window:
Figure 43: 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.
8. 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 44).
There are four main areas in this window:
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