Dcam User Guide-Grayscale Camera Calibration (Illunis, Redlake)

Sections:

About Camera Calibration
When to Calibrate
Preparing for Camera Calibration
Setting Camera Height
Calibrating the Grayscale Cameras
Troubleshooting Focus Calibration
Troubleshooting Whiteboard Calibration

About Camera Calibration

Calibration is a process to establish the correct camera settings for capturing high quality images. There are 2 sets of calibration steps: 1 set for color cameras and 1 set for grayscale cameras. When the camera is plugged into the computer, DCam automatically identifies which camera is attached.

Note: Calibration is the key to capturing good quality images.

When to Calibrate

The Device Calibration tab in the footer shows if the camera has already been calibrated. However, if the camera environment has changed, even if this tab shows that the camera has been calibrated, you may need to recalibrate. At a minimum, the camera should be calibrated under the following circumstances.

• Each day as you start to capture images 
• If any of the following have changed: 
  
  • Camera height 
  • Capture board height 
  • Lighting 
  • Change in type of document, such as transitioning from a single page to a book). 
• After lunch or a long break 
• Every time you create a new folder if the lighting or height of the camera is changed.

Preparing for Camera Calibration

To prepare for camera calibration, follow these steps:

Step 1: Turn on workstation lights 15 minutes before starting calibration to ensure they are at a full and consistent luminosity.

Step 2: If possible, eliminate other light sources, including light from windows, doors, or other lighting systems.

Note: Recalibrate the camera any time there is a change in lighting.

Step 3: Verify that the camera and stand are set up on a hard, sturdy surface, such as a solid desk or table.

Step 4: Use the bubble level to verify that the table, copyboard, and camera stand surfaces are parallel and level. This keeps the entire capturing field in focus once the camera is calibrated. Level these surfaces in the following order:

• Table 
• Copyboard 
• Camera stand

Step 5: Remove the camera lens cap.

Step 6: Turn on the computer.

Step 7: Turn on the camera.

Step 8: To start the application, on the computer’s desktop, double-click the DCam icon.

Step 9: Verify that the correct camera is selected by looking at the current device designation in the bottom-right section of the home screen. If the correct camera is not selected, select the correct one in preferences.

Step 10: In the folder, find the largest document to be captured in the folder.

Step 11: Ensure that the camera is set to a height that will maximize the capture of the document. (See Setting Camera Height).

Step 12: Create folders in the Folders section of the Manage Projects, Listings, and Folders screen. (See Creating a New Folder).

Setting Camera Height

Camera height should be set in relation to the largest document in the folder. Ensure that the entire document can be viewed. Additionally, establish a camera height that allows for the capture of many document sizes. The best practice is to keep the camera height at 22 inches (56 centimeters) or higher from the copy board.

Step 1: Click Manage Projects, Listings, and Folders.

Step 2: Identify the correct listing, and create the required folder. (See Creating a New Folder.)

Step 3: At the bottom of the folder screen, click Save and Capture. This starts the calibration steps.

Step 4: Place an open book or the largest document from the folder on the copy board under the camera lens, and click Refresh Image. The image displays on the screen.

Step 5: Adjust the camera height, and continue to click Refresh Image until you get the camera at the correct height.

• If the whole document page cannot be viewed, then move the camera up. If the document does not fill the viewing area, then move the camera down.  
• If a document is larger than the camera can capture at the highest position, set the camera height for most of the page sizes, and capture the large page separately. (See Capturing a Large Document.) 
• A best practice is to keep the camera height at 22 inches (or 56 centimeters) or higher from the copy board in most cases.  
• A thin black border that is ½ inch to inch wide (1.2 to 2.5 centimeters) should run around all 4 sides of the document

Step 6: Click Continue with Calibration.

Calibrating the Grayscale Cameras

To calibrate grayscale cameras, perform the following steps in order.

Note: There are instructions for each calibration task on the left panel of the DCam calibration screens.

Beginning Calibration

As a precursor to calibration, obtain records to capture and create a new folder.

Step 1: Click Manage Projects, Listings, and Folders.

Step 2: Identify the correct listing and create the required folder. (See Creating a New Folder.)

Step 3: At the bottom of the folder screen, click Save and Capture.

Calibrating Focus

Calibrating focus produces sharp, crisp lines in text and writing

Step 1: Place the largest document in the folder on the copy board. If capturing a book, open the book to a center page, and place wedges under the front and back covers to make it as level as possible.

Step 2: Manually adjust the camera height so the entire document can be seen in the screen’s capture frame. It should fill as much of the frame as possible, leaving a black border along all 4 sides of the document or book. If needed, turn the document so that it fits in the frame with the longest side of document running along the longest side of the camera frame. A best practice is to keep the camera height at 22 inches (56 centimeters) or higher from the copy board.

Step 3: Remove the document, and place the focusing target on the capture board.

Step 4: Click Start or Reset. Do not allow any object in the viewing area while the camera is being focused.

Step 5: Manually focus the camera lens by turning it either clockwise or counterclockwise until the green column and focus score rises to the maximum.

Note: Turn the lens a bit, and then stop and let the system think. Then turn it again, and let the system think, repeating until the maximum number is achieved. If the camera lens is continuously moving, the system may lock up.

The green number has no significance except as a point of reference.

Step 6: To begin checking the camera’s focus, find the lines next to 1.0 on the focus card, and position them on the copy board near the center of the viewing field.

Step 7: Using your mouse’s scroll wheel, zoom to 2,300%. Position the image on the screen to clearly see the 1.0 vertical and horizontal lines.

Step 8: The darkest pixels are called fully blocked pixels. The pixels that transition from the blocked pixels to the light background are transitional pixels. When you have positioned the lines on the card so that they are horizontal and vertical, the edges should be crisp with no more than 2 transitional pixels on either side of the fully blocked pixels.

Note: Rotate the wheel away from you to zoom the pixels larger. Rotate the wheel toward you to zoom the pixels smaller.

Step 9: If you need to, manually adjust the camera’s focus by using the arrow buttons under manual focus in the left control panel. Continue adjustment until you achieve the maximum focus score with no more than 2 transitional pixels on either side of the fully blocked lines.

• When using the manual focus controls, first adjust to the left until slightly out of focus, and then adjust to the right until the best focus is achieved, which displays as the maximum green and highest score.
• To make slight focus adjustments, click the left and right single arrow buttons. 
• To make greater focus adjustments, click the left and right double or triple arrow buttons. 

Note: When calibrating the camera to capture a book, perform all calibration steps on the top of the book.

Step 10: Once the target is focused, click Next.

Troubleshooting Focus Calibration

Step 1: Out of focus is a quality control characterization that may lead to recapturing images. This result is characterized by blurring in all directions—as opposed to a single direction, as with motion blurring.

Step 2: Out-of-focus images can result when the camera lens is not calibrated to have a large enough depth of field.

Step 3: The depth of field is the distance between the nearest and farthest points from the camera where an image is in focus. If calibration did not provide a large enough depth of field for the variance of documents in the collection, as is necessary especially with books, images may lose their crisp focus as pages are turned. Loss of focus usually occurs in the same location, image after image.

Step 4: The F-stop on a camera affects the depth of field. Smaller numbers, such as F-2 and F-4, have less depth of field. Larger numbers, such as F-11 and F-16, have a greater depth of field.

Note: Never change the F-stop from F-8 unless directed to do so by your supervisor.

Step 5: Generally, when the lens is set at F-8, at least 0.5 inches (1.27 centimeters) is in focus. This is important when capturing a book. For a thick book, you need to occasionally reset the focus, since some pages are outside of the depth of field. Put wedges under the front and back covers so the entire surface of the book is in focus. Open the book to a middle page, and put the calibration tools on the book when calibrating.

Calibrating the Lighting with a White Board

Calibrating the lighting with a large white foam-core board ensures that lighting is evenly distributed across the entire image-capture area and that dark areas are adjusted to give an even, balanced background. You should have this white foam-core board as part of your workstation equipment.

Step 1: Remove the focus target that you used during focus calibration.

Step 2: Because imperfections show on captured images in a bright white halo effect, ensure that the whiteboard is free of dust, spots, dents, smudges, or anything else.

Step 3: Place the foam-core board on the copy board with the dull side up. The whiteboard must cover the entire viewing area. While the camera is adjusting, the Next button is disabled, and the message “Adjusting shutter…” displays.

Ideally, the whiteboard displays an even green or yellow-green color across the entire viewing area. If there are lighting problems, however, the colors in the DCam viewing area differ from the even green ideal. These differences represent various light conditions. DCam displays warning messages. The following table describes what different colors and patterns might mean.

It is normal to see colder colors in the corners and warmer colors in the center of the copy board. However, your calibrated white board should never show any dark blue or red areas. If whiteboard calibration is successful, “Whiteboard Good” will display in the left panel.

Step 4: Click Next. Wait until the screen turns white before you remove the whiteboard.

Step 5: If whiteboard calibration is not successful, correct any problem before continuing.

Troubleshooting Whiteboard Calibration

You may see a number of common problems with whiteboard calibration.

• Bright white halo shapes on images can indicate dust, spots, dents, or other imperfections with the foam-core board. Ensure the whiteboard is free of dust, spots, dents, smudges, or anything else. Additionally, if there are dust spots or hairs on the camera lens, they can show faintly in the background on every captured image. 

Use tools to zoom in on a problem area to inspect more closely.

• A common problem occurs when the whiteboard is placed on the copy board at a skewed angle, leaving one corner dark. 
• An item left on the whiteboard can trigger 3 warnings in the left panel. 
• Sometimes it is difficult to get even lighting. Be aware of light coming from windows because it changes throughout the day as the sun moves. Also be aware of overhead lights that automatically turn on and off because of movement sensors. 
• Whiteboard calibration detects hot spots and cool spots in the lighting distribution and tries to compensate so that the lighting is even. If, however, the system is unable to calibrate the whiteboard, DCam will display an error message. To fix the problem, use the tables below, and address environmental lighting sources. Adjust the light bars in the control panel for more or less light. Below are some examples of lighting problems.

Problem	Example
Whiteboard with red means too much light
Whiteboard with red spot may point to area of bright light reflection
Whiteboard with red section may mean too much light in one area
Whiteboard with blue may mean not enough light is available

The following table suggests solutions for correcting hot and cold spots.

Calibrating Exposure

Exposure calibration measures the tonal range of an image by comparing a standard set of gray tones that is stored within DCam against the shades of gray in a grayscale card you have placed on the copy board. This card consists of 255 values, from the brightest white to the darkest black. To calibrate these values, Dcam identifies certain patches of the grayscale card marked as A, M, and B. It then ensures that all values on the card fall between the measurements of 23 and 242, (out of a possible range between 0 and 255). If values fall outside these measurements, tonal information that creates different shades of gray on the records you capture can be lost because of a light-exposure error. (See Understanding Capture Problems.)

Step 1: Place the grayscale card vertically on the copy board in the center of the viewing area so that light can wash across it evenly.

• If you are capturing a book, open it to the center pages with wedges under the front and back covers to make it as level as possible, and then place the grayscale card or clamshell (the plastic case with color and shade targets within it) on top of the book. 
• If the grayscale card is curled, worn, or dirty, replace it.  

Note: Do not touch the surface of the grayscale card with your fingers. The oil from your fingers can affect the card grayscale values over time.

Step 2: Verify that the radio button Automatically Locate Grayscale Card is selected.

Step 3: The type of card being used should be displayed in the top of the calibration panel. If not, click Choose a different card.

Step 4: Select the correct card from the options available, and click OK.

Step 5: DCam automatically locates the grayscale card patches. When they are found, it establishes the camera’s exposure and other settings.

Step 6: There are situations when it is necessary to manually locate the grayscale card patches: Dcam cannot automatically locate the grayscale card when documents are whiter than the A-patch on the grayscale card, or there is not enough light to automatically identify the grayscale card. If Dcam has difficulty automatically locating the grayscale card, check the following:

• Make sure you selected the correct grayscale card. 
• Remove excess clutter on the copy board surface, and retry. 
• Make sure the grayscale card is centered. 
• Move the grayscale card to different positions or slightly different angles, and retry. 
• Move lights to provide more light to the copy board. 

Step 7: If DCam still has trouble locating the grayscale card, manually locate the grayscale patches by following these steps. Otherwise skip to step 9.

• On the exposure screen, click Manually Locate Grayscale Patches. The 3 sampler targets and labels display.
• With your mouse, click and drag the targets onto the grayscale patches, as directed. The sampling tool displays orange when the pixel values are inconsistent. For example, when placed partially between 2 patches, the sampler will have an inconsistent value. Make sure the sampler is correctly positioned. 

Step 8: Click Start. The camera takes several quick shots, so make sure not to move the grayscale card. On your computer screen, red boxes appear around the A, M, and B patches of the grayscale card

• If during calibration DCam cannot identify the A, M, and B patches, a message reminds you to ensure that you have selected the correct grayscale card. 
• If DCam indicates a bad sample, check the grayscale card for damage. 
• If the relative position of the samplers does not appear correct, DCam displays a warning prompt.  
• The sampler values should follow the rule A is greater than M, which is greater than B, (A > M > B), which could be restated as white is greater than gray, which is greater than black. If the sampler readings do not meet this rule, DCam will display a warning prompt.

Step 9: If the exposure calibration is successful, a green circle with a check mark displays with the text grayscale passes.

Step 10: After grayscale calibration is complete, check the adjusted grayscale values. They should be in the following ranges:

• A—(White): 243 or less
• M—(Gray): between 104 and 108
• B—(Black): greater than 23

Step 11: You may have to repeat grayscale calibration because of 1 of the following issues:

• Some archives require images to be captured with a minimum value of dots per inch (DPI). During grayscale calibration, DCam measures the DPI. This value increases the closer the camera is to the copy board. If the grayscale calibration does not pass, or if the DPI values are not correct, adjust the lighting, and start the calibration over again
• If you are working with documents that are whiter than the A patch of the grayscale card, complete these steps: 
  
  • Click the Use Bright White Sampler check box.  
  • Place a bright white document onto the copy board next to the grayscale card. 
  • Click and drag the bright white sampler target onto the document. 

Step 12: Click Next.

Checking LSI

The LSI check ensures that the digital image of the record shows even the finest lines of information as written on the original document. Perform an LSI check by completing the following steps:

Step 1: Find thinly-lined text that represents the collection. The chosen text can be either handwriting or type as long as it is thin, not faded, and not damaged. Do not select an embellishment, a finishing flourish on a character, preprinted lines, or lines on a seal (such as on a government seal).

Step 2: Place the document you have chosen on the copy board. If you are capturing a book, open the book to the center pages with wedges under the front and back covers to make the pages as level as possible.

Step 3: Click Next. Your screen displays a green selection box and an LSI area tool dialog. An LSI score displays in green. This first reading is an error because the entire document and the copy board are within the selected green box.

Step 4: Drag the corner of the selection box toward its center to reduce its size to the point it only selects the thin representative text you chose. Once the thin text is highlighted with the green box, the LSI score displays the correct values for the chosen text.

Step 5: Continue to work with the box until you have achieved an acceptable LSI score of 80 or above; however, a marginal LSI score is acceptable. Below are examples of 3 LSI results.

• An LSI score of 90 or above is optimum preference. Click Next. 
• If the LSI score is 80–89, it is marginal but still acceptable. Click Next. 
• If the LSI score is 79 and below, it is an unacceptable LSI. (See the Troubleshooting LSI Calibration section).

Step 6: Once there is an acceptable LSI score, a green circle with a check mark displays. Click Next.

Step 7: DCam indicates that the score has been saved. Click Next to capture images.

Calibrating LSI for Microfolders

Some projects require the creation of several small folders (microfolders) that can be captured in a very short time. The content of these folders is often very similar. For these projects, instead of calibrating the LSI for each folder, you can calibrate the LSI once and reuse it for numerous microfolders. However, to reuse the LSI you need permission and a code from the Quality team. This code is valid for approximately 2 hours and for that project only. If it takes longer than 2 hours to capture the images, you must recalibrate LSI for the next folder. Perform the following steps to calibrate LSI for microfolders:

Step 1: Gather all the material to be captured, and create all the needed folders in advance.

Step 2: When you are ready to capture the images, on the Manage Projects, Listings, and Folders screen, double-click the project to be worked on. The project information screen displays.

Step 3: In the Reuse LSI Authorization field, enter the code received from the Quality team.

Step 4: On the Managing Projects, Listings, and Folders screen, click the first folder, and capture the images until completed.

Step 5: Repeat the process on the second and subsequent folders, capturing images until capturing is finished or the LSI reuse code expires.

Troubleshooting LSI Calibration

The only way you can improve LSI is to increase the number of dots per inch (DPI) the system is detecting across the sample of thin text you have chosen. Do this by lowering the camera. Select the largest document that you have in the group of records on which you are basing the folder. Complete the following steps:

Step 1: To return to the LSI focus screen, click Back.

Step 2: Move the camera down to maximize the array for the largest document, and refocus.

Step 3: Click Next, and again check the LSI with the chosen text.

Step 4: Click Next.

Step 5: If the LSI score still does not pass, contact your supervisor. You may need to request an exception.

• If capturing 2 pages at once, discuss how to resolve the LSI issue with your supervisor or manager. You may be asked to capture single pages instead of 2 pages at once.  
• If you choose the single-page option, move the camera height down to capture images at a higher DPI.  
• Redo all calibration steps, and check the LSI again. (Only capture in this way if you are directed to do so by your supervisor.) 
• If you are working with the largest, single document in the group of records and have adjusted the camera height prior to calibration—making sure the longest side of the document is along the longest side of the camera viewing area—then lowering the camera will not work as a solution. That is, the LSI will be as good as you will be able to get it. To let the Quality team know why LSI is unacceptable, complete the following steps to request an exception: 
  
  • Click Back. 
  • Place the largest document on the copy board to fill the camera’s viewing area. 
  • Place the chosen document with the thin text visible. 
  • Click Next. 
  • Change the green highlighted area to show only the text you have chosen. 
  • Click Next.