Transcript
Image Digitization Workflow and Documentation
Prepared by Anna Rybakov, Digital Lab Manager Research Library, Special Collections American Museum of Natural History November 2013
Image Digitization Overview
The following is an overview of the procedures and workflows used by the Digital Lab Manager to oversee the digitization of hundreds of images, weekly, at the item level. The standards presented in this document are based on the FADGI’s Technical Guidelines for Still Images (2010) as well as internal needs and constraints. Material Types: Our primary focus is on black and white negatives (film and glass plate). Original negatives are always scanned as digital masters whenever possible. If a negative is unavailable, its photographic print is scanned instead. Many color images have already been previously scanned but occasionally we address color transparencies and slides. Digitization Equipment: A flatbed scanner (Epson V750 Pro) is used for scanning all of the above material types. The scanner has a wide range of ppi settings, handles both reflective and transmissive items, and can comfortably accommodate most of the dimensions of our materials (up to 8.5” x 11”).
Image Digitization Table of Contents
Slide 1: The general workflow of the Digital Lab Manager Slide 2: The general workflow of volunteers & interns overseen by the Digital Lab Manager. Slide 3: A detailed description of the Search process used to locate images Slides 4-9: The scanning process carried out by everyone who uses the Digital Lab. For a more detailed explanation of scanning please see our official Scanning Instructions Manual as well as the Reviewer’s Manual. Slides 10-14: The image correction process completed by interns, using Adobe Photoshop CS5. For a more detailed explanation of processing please see our official Processing Instructions Manual. Slides 15-25: The image correction and metadata embedding process implemented by the Digital Lab Manager, using Adobe Lightroom.
Image Digitization Workflow Digital Lab Manager SEARCH - Disk index* - Finder If no digital image exists: SCAN
CORRECT/METADATA
SAVE
DATABASE
- Epson Scan - Epson Perfection V750 Pro
- Adobe Lightroom - Adobe Photoshop
- export archival TIF & JPG derivative to server
- create Omeka record & upload JPG
If (uncorrected) digital image exists: CORRECT/METADATA
SAVE
DELETE
- Adobe Lightroom - Adobe Photoshop
- export archival TIF & JPG derivative to server
- remove unedited image off of hard drive
* The Disk index is a periodic file analysis which generates a searchable spreadsheet listing the contents of our server, legacy database, and external hard drive; all of which store images in varying degrees of completion.
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Image Digitization Workflow If image has not been previously scanned:
Volunteer Scanners: SCAN - Epson Scan - Epson Perfection V750 Pro
SAVE - weekly desktop folder
Digital Lab Manager: transfers the scanned images into the Reviewer’s folder.
Reviewers*: QC
PASS or FAIL
- Adobe Photoshop - Finder
- “done” folder or trash
Digital Lab Manager: transfers the “done” images onto external hard drive for future processing. Images that failed are flagged for rescan.
Processing Interns: CORRECT
SAVE
- Adobe Photoshop
- “done” folder
Digital Lab Manager: imports “done” images into Lightroom. Add Metadata. Review & Correct where needed. Convert to 8-bit. Export. Save. Delete from desktop.
* Reviewers are Volunteers who have shown consistent excellence in scanning and are sensitive to the criteria of a high quality scan. Reviewers provide triage for the Digital Lab Manager by ensuring digital files adhere to QC standards prior to their storage or processing.
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Image Digitization Workflow STEP 1: SEARCH - Disk imaging - Finder Search using Disk Imaging ● Periodic file analysis generates a searchable Excel spreadsheet of all items on server. ● Image numbers are entered in the “Search” field. Assess Results ● Excel indicates "cannot find data" if that image number does not appear on any of the disks. ● If results do appear, note on which disk they fall.
location on disk disk number Retrieve and Verify/Correct Image ● If the image wasn't found, then it will need to be scanned. ● If the image was found, mount appropriate disk using ExpanDrive to access existing scan. ● If the scan is in compliance with the standards as specified in this document, proceed to deliver it as needed.
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Image Digitization Workflow STEP 2: SCAN - Epson Scan - Epson Perfection V750 Pro
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Scanning is routinely conducted by both volunteers and interns. The Digital Lab Manager selects and provides physical negatives for scanning.
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For best results, the scanning environment is kept dimly lit with no direct light falling onto the computer monitor.
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The goal for scanning is to create a high quality surrogate that remains true to the physical negative and needs little manipulation in post.
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Skills needed: acute attention to detail, care in scanning and managing digital files, as well as cautious handling of the physical negative and equipment.
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Image Digitization Workflow STEP 2: SCAN - Epson Scan - Epson Perfection V750 Pro Clean and Prepare ● Clean the scanner bed at least once a week, or as needed, with glass cleaner wipes and/or microfiber clothes. ● Ensure glass is completely dry before setting a negative on the bed. ● Clean the anti-newton glass prior to each use as it is very prone to fingerprints. ● Only use the horsehair brush to remove dust from the negatives by gently sweeping it across the front and back of the negative. ● Eradicate dust on both sides of the negative and the scanner glass with the horsehair brush before placing the negative on the scanner bed. Safe Handling and Proper Placement ● Always wear gloves when handling all negatives and any glass surfaces. ● Negatives should always be scanned emulsion-side down (facing glass/light source). To determine which side is the emulsion-side, hold the negative perpendicular to a light source and locate the side that appears to be more matte. This is the emulsion side. ● Plastic film negatives should be placed directly on the scanner glass. Since curling often occurs, use a pane of anti-newton ring glass to flatten it. ● Glass plate negatives should be carefully placed atop the scanner bed glass with every effort made to avoid scratching and dropping. Sandwich plastic negs between scanner glass and anti-newton ring glass.
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Image Digitization Workflow STEP 2: SCAN - Epson Scan - Epson Perfection V750 Pro Set Scan Settings In Epson Scan, choose these settings: ● Document Type: Usually this will be "Film (with Film Area Guide.)" If scanning several 35mm negatives or slides, it is advantageous to use one of the plastic negative holders. In this rare case, the setting "Film (with holder)" should be selected. If scanning a print, select “Reflective”. ● Film Type: This will usually be "B&W Negative Film" — change as needed. ● Image Type: "16-bit Grayscale" for black and white images and "48-bit Color" for color images. ● Scanning Quality: Always choose "Best." ● Document Size & Target Size: leave both at 8x10 regardless of negative size (will be cropped later). ○ None of the boxes under “Adjustments” should be selected ● Click “Preview” to generate initial image.
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Image Digitization Workflow STEP 2: SCAN - Epson Scan - Epson Perfection V750 Pro Set Resolution ● Resolution/Image Size: resolution and file size (MB) have a directly proportional relationship (Rotate-->Arbitrary can also be used to adjust orientation. Sharpen ● Zoom in to view the image 1:1 and launch Unsharp Mask window. For most images at this resolution, a radius of 1.3 pixels is appropriate. Adjust slider until you see a slight (not dramatic) sharpening (it is helpful to be looking at an area that has the finest detail and highest contrast, as these areas tend to over- sharpen first.) Be conservative in sharpening, it is irreversible.
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Image Digitization Workflow STEP 3: CORRECT - Adobe Photoshop
Correct tone (and then color if applicable.) ● Correct for anomalies (light leaks, very uneven lighting) using adjustment layers and then flatten those layers. ● If image has too much contrast, adjust accordingly, using the Brightness/Contrast sliders. ● Determine what area of the tonal range needs more definition. Generally, it will be the lightest lights and the darkest darks, which can be corrected using the Shadow/Highlight tool (use very conservatively — bring out as much information as possible without excessive flattening.) If the mid-tonal range needs more distribution, adjust the Curves. The tonal range of most images are improved with a slight s-curve.
Slight S-curve. Always toggle “preview” to ensure tonal distribution is improved.
Only adjust “Contrast” here -- Brightness should be fine-tuned using “Levels”
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Image Digitization Workflow STEP 3: CORRECT - Adobe Photoshop
Correct color (if applicable) ● Launch Color Balance (command + B.) ● If you are working from color slide film (positive film) check your colors against the original on the light table. Often positive film will turn red with age, so be wary of this variation. ● Images captured from scanners are usually over-saturated. Compensate by launching the Hue/Saturation slider (command + U.)
Image hues should be adjusted with “Color Balance”.
Adjust “Saturation” on Hue/Saturation slider. The lightness of the image should be adjusted through “Levels”.
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Image Digitization Workflow STEP 3: CORRECT - Adobe Photoshop Spot correction ● The most efficient tool for quickly eliminating small spots (due to dust, scratches, conservation issues, or incamera debris) is the Spot Healing tool. The Spot Healing tool works well except for the occasional problem near the edges. If the Spot Healing Brush is not working for a particular area, switch over to the Clone Stamp, which offers a higher degree of cloning control.
What to correct and what not to correct… ● Generally adjust zoom to 50% and adjust all distracting, highly visible defects. All dust and scratches are repaired with two exceptions: ○ a.) plentiful dust/dirt around edges of image frame. If they do not interfere with the content/focus of the image and are too plentiful/dense to efficiently eradicate, they are best left alone. ○ b.) large cracks that are difficult to correct without overwriting some portion of the original image. Small cracks and cracks that do not overlap important content are always corrected, as this can be easily done without risk of overwriting important details.* * How to handle Newton Rings in scans: ● Newton rings occasionally appears on scans (generally on the newer film negatives in areas of little detail — where the negatives are very thin.) When this occurs, the negative may need to be rescanned, depending on the severity of the rings and whether they overlap detailed areas. ● If the film is flat enough to be rescanned without glass compressing it downward, rescan in this manner. This should alleviate most of the Newton rings. ● If the moire patterns are minimal enough and confined to areas of less detail, they may be cloned out. ● Difficult moire patterns or patterns on important negatives should be outsourced for drum scanning.
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Image Digitization Workflow STEP 3: CORRECT - Adobe Photoshop
Save ● Ensure your TIFF file is flattened before saving (has no layers.) ● Ensure "Embed Color Profile: Adobe RGB (1998)" is selected on the save menu. ● On the "Tiff Options" window, select "None" under Image Compression, "Interleaved" under Pixel Order and "Macintosh" under Byte Order. Note: Bit-depth conversions and metadata embedding will take place in bulk using Lightroom.
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Image Digitization Workflow STEP 3: CORRECT - Adobe Lightroom
Lightroom is used by the Digital Lab Manager. This software is used to process single image requests and batches as well as QC intern’s Photoshop work. Lightroom is also used for batch metadata embedding and export. Import ● In the Library module select Import. ● Select Source i.e. find path to desired folder. Metadata ○ apply preset Copyright metadata during import. Type in any relevant keywords (e.g.: Dimock, Lumholtz, etc.) ●
Select desired folder of images and hit import. Preview rendering will begin. Once completed, selected images are now available in your “catalog” in the Library module.
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Image Digitization Workflow STEP 3: CORRECT - Adobe Lightroom Metadata can be viewed/adjusted in Library module. Image corrections are performed in Develop module.
Batch Prepare ● In the Library module, working in your specific folder of images, Select All and Flip Horizontally.
Select detailed area of image for Sharpening preview using cross hairs box.
Individual Adjustments ● Select first photo and click into the Develop module. All adjustment tools are in the scrollable right hand toolbar. Sharpen ● Use cross-hairs box to select an area that has the finest detail and highest contrast. ● Adjust slider until you see a slight (not dramatic) sharpening. Be conservative in sharpening as it often brings out a lot of noise/dust in the overall image.
Adjust slider gradually while continuing to track changes both in the preview window and the entire image.
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Image Digitization Workflow
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STEP 3: CORRECT - Adobe Lightroom
Crop ● Adjust image rotation by using the Crop Overlay tool. A bounding box will appear around your image as well as a grid to help you straighten your image. ● Use corner anchors to rotate image and midpoints to crop. Be sure to preserve a black border of at least 3% of the total image dimension around the perimeter of the negative (or glass plate) to keep edge information intact. ○ Note: borders cannot be created in Lightroom. Export image to Photoshop to add borders if needed. ● Once image is at desired angle and size, close “Crop & Straighten” menu.
Select Crop Overlay icon to begin rotation.
Move midpoints in and out to crop image.
Rotate at corners to achieve correct orientation.
Image Digitization Workflow STEP 3: CORRECT - Adobe Lightroom
Correct Tone ● Use the “Basic” and “Tone Curve” drop down menus to adjust image tones. ● Start by manipulating the Tone Curve, create slight S-curve and conservatively adjust highlights/shadows as needed. ● Use Contrast and Highlights to compliment the Tone Curve changes. ● If image needs more brightness adjust Exposure. ● If image needs more pronounced darks, modestly increase Blacks. Note: All actions can be tracked in the History drop down on the left hand side toolbar.
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Image Digitization Workflow STEP 3: CORRECT - Adobe Lightroom
Spot correction ● Small spots can be fixed using the Spot Removal tool which has both Clone and Heal capabilities. Make sure to Zoom in (shift+) to problem area before beginning to heal/clone. ○ Note: The Spot Healing Brush in Photoshop is much more dynamic. For irregular spots, larger problems areas and/or more complicated corrections export image to Photoshop. ● Once spots/dust removed, close Spot Edit menu. Sampling area.
Area to be corrected.
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Image Digitization Workflow STEP 3: CORRECT - Adobe Lightroom
Adjustment Brush ● For specific areas that need repair (overexposed/underexposed) use the Adjustment Brush tool. ● Run the brush over the problem area and manipulate Effect sliders to achieve a seamless correction. ○ Note: Photoshop offers more adjustment precision than our current version of Lightroom (3). For most layer adjustments export to Photoshop. If problem occurs in flat area with little visual information Lightroom will suffice.
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Image Digitization Workflow STEP 3: CORRECT - Adobe Lightroom
Finish ● Once all necessary changes have been made, click the Go Forward arrow to bring up the next image and repeat correction steps. ○ Note: All changes/adjustments will be saved in Lightroom and the image file will not reflect those changes until export.
Go forward/ go back arrows.
In the thumbnail scroll, current selection will have a light grey background.
Quick source info: path, total, # selected, and file name.
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Image Digitization Workflow STEP 3: CORRECT - Adobe Lightroom
Prepare Export ● Launch ExpanDrive and mount appropriate server for your specific tifs and derivatives. ● Open the disks and note the total number of existing images. Once export from Lightroom is complete, verify that the new total is accurate based on how many images were imported.
E.g.: For 5x7 negs, mount disk 11 for tifs as well as disk 5 for jpg derivatives.
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Image Digitization Workflow STEP 3: CORRECT - Adobe Lightroom
Export JPEGs ● Select all desired, completed images and select Export. ● The export window will appear. ● Export Location: select Choose and find the path to appropriate disk and folder*. *Note: one-off jpegs go directly into a designated size folder. All other exports go into a designated size folder within the “To Upload” folder.
File Settings ○ Format: Jpegs ○ Color Space: AdobeRBG(1998) ○ Quality: maximum (100) ○ Nothing else should be checked. Image Sizing ○ Check Resize to Fit and select: Long Edge ○ Check Don’t Enlarge ○ Input 12 inches ○ Resolution: 72 ppi Nothing else should be checked. Select Export.
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Image Digitization Workflow STEP 3: CORRECT - Adobe Lightroom
Export TIFFs ● Select all desired, completed images and select Export. ● The export window will appear. ● Export Location: select Choose and find the path to appropriate disk and folder. File Settings ○ Format: TIFF ○ Color Space: AdobeRBG(1998) ○ Compression: None ○ Bit Depth: 8 bits Image Sizing ○ Uncheck Resize to Fit ○ Resolution: 72 ppi or scanning resolution, if known. Nothing else should be checked. Select Export.
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Image Digitization Workflow STEP 3: CORRECT - Adobe Lightroom
Finish ● Once Lightroom export has been completed and the transfer to server is verified, images can be removed from Lightroom and deleted from the desktop.
For QC of images processed by interns, procedures are largely identical to the aforementioned Lightroom workflow with the following exceptions*: ● Images do not need to be flipped horizontally. ● No sharpening needed. ● Adjustments/corrections are minimal, if any.
*These steps should have been adequately addressed while processing in Photoshop.
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