Image Digitization - American Museum of Natural History · 2014-04-24 · Image Digitization Overview The following is an overview of the procedures and workflows used by the Digital

Image Digitization

Prepared by Anna Rybakov, Digital Lab ManagerResearch Library, Special CollectionsAmerican Museum of Natural History

November 2013

Workflow and

Documentation

Image DigitizationOverview

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”).

http://www.digitizationguidelines.gov/guidelines/FADGI_Still_Image-Tech_Guidelines_2010-08-24.pdf

Image DigitizationTable of Contents

Slide 1: The general workflow of the Digital Lab ManagerSlide 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 WorkflowDigital Lab Manager

SEARCH

- Disk index*- Finder

If no digital image exists:

SCAN

- Epson Scan- Epson Perfection V750 Pro

CORRECT/METADATA

- Adobe Lightroom- Adobe Photoshop

SAVE

- export archival TIF & JPG derivative to server

DATABASE

- create Omeka record & upload JPG

If (uncorrected) digital image exists:

CORRECT/METADATA

- Adobe Lightroom- Adobe Photoshop

SAVE

- export archival TIF & JPG derivative to server

DELETE

- 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

SCAN


SAVE

- weekly desktop folder

QC

- Adobe Photoshop- Finder

PASS or FAIL

- “done” folder or trash

Reviewers*:

If image has not been previously scanned:

Volunteer Scanners:

Processing Interns:

CORRECT

- Adobe Photoshop

SAVE

- “done” folder

Digital Lab Manager: transfers the “done” images onto external hard drive for future processing. Images that failed are flagged for rescan.

Digital Lab Manager: imports “done” images into Lightroom. Add Metadata. Review & Correct where needed. Convert to 8-bit. Export. Save. Delete from desktop.

Digital Lab Manager: transfers the scanned images into the Reviewer’s folder.

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* 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.

Image Digitization WorkflowSTEP 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.

disk numberlocation on disk

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 WorkflowSTEP 2: SCAN


● Scanning is routinely conducted by both volunteers and interns. The Digital Lab Manager selects and provides physical negatives for scanning.

● For best results, the scanning environment is kept dimly lit with no direct light falling onto the computer monitor.

● The goal for scanning is to create a high quality surrogate that remains true to the physical negative and needs little manipulation in post.

● 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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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.

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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.


STEP 2: SCAN


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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STEP 2: SCAN


Set Resolution● Resolution/Image Size: resolution and file size (MB) have a directly proportional relationship (<res =

<MB.) Resolution should be adjusted until the correct file size (MB) is reflected. (This can be approximate.)

● The larger the physical negative, the more information that negative can hold. Subsequently, larger physical negatives should be scanned at larger file sizes (MB.) The idea is to capture all of the information held on a negative, but not more, as doing so would waste space on the server.

● Below are recommended resolutions for the negatives we encounter most often; black & white negatives in 4 sizes. Negatives that fall outside these dimensions require special attention.

Black & White Negatives:Size DPI 4x5 10505x7 8756x8 8008x10 750

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Make Selection and Correct Exposure

● Make a selection using the Marquee tool around the subject of the image; within the bounds of the image to be scanned (excluding the negative edge.)

● Hit Auto Exposure button at bottom left of panel. This will bring the image into the correct tonal ballpark — although the image is typically a bit over-saturated and has a bit too much contrast. Small tweaks can be made using the Image Adjustment sliders.

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Image Adjustments ● Pull the selection boundary box

to include ALL of the negative (we want the edges of the negative to show in the final scan).

● The auto-exposure adjustment usually gives the image too much contrast and saturation, so open the Image Adjustment window (fourth icon under “Adjustments”) and lower the contrast (compensate by increasing brightness). Make sure to capture the full range of tones—don't let the lightest lights and the darkest darks disappear--it is better to err on the side of too little contrast (flatness) in this step than to lose tones.

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File Name/Location ● Click “Scan”.● File Save Settings window will

automatically pop up.● Choose the destination folder for the

image by clicking on the "Choose" button. ● Files will be named according to the

image's AMNH negative number printed on the negative envelope.

● The "Start Number" for the File Name must always be exactly 3 digits. The Prefix box allows alphanumeric free text. Therefore, if the AMNH negative number is 6 digits long, the first Prefix box gets the first 3 digits. If the AMNH negative number is 5 digits long, the "Prefix box" gets the first 2 digits. If image number is followed by any letters put them at the beginning of the numbers in the Prefix box.

● Image format○ Type: should always be set to

TIFF.● Hit “OK” to initiate scan.

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Image Digitization WorkflowSTEP 3: CORRECT

- Adobe Photoshop

Adobe Photoshop is used by digitization interns to process legacy scans. Their corrected images are imported into Adobe Lightroom for final review, batch metadata embedding, and export.

Prepare ● Since negatives are scanned emulsion side-down, all images will need to be flipped horizontally. Once flipped,

no more flipping should be done — only rotating.● Use the crop tool to simultaneously fine-tune the cropping and the rotation of the image. 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: Transform or Ruler-->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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- 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.

Only adjust “Contrast” here -- Brightness should be fine-tuned using “Levels”

Slight S-curve. Always toggle “preview” to ensure tonal distribution is improved.

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- 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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- Adobe Photoshop

Spot correction● The most efficient tool for quickly eliminating small spots (due to dust, scratches, conservation issues, or in-

camera 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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- 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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- 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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- Adobe Lightroom

Batch Prepare● In the Library module, working in your

specific folder of images, Select All and Flip Horizontally.

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.

Metadata can be viewed/adjusted in Library module. Image corrections are performed in Develop module.

Select detailed area of image for Sharpening preview using

cross hairs box.

Adjust slider gradually while continuing to track changes both

in the preview window and the entire image.

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- 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.

Rotate at corners to achieve correct orientation.

Select Crop Overlay icon to begin rotation.

Move midpoints in

and out to crop image.

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- 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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- 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.

Area to be corrected.Sampling area.

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- 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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- 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.

In the thumbnail scroll, current selection will have a light grey background.

Go forward/ go back arrows. Quick source info: path, total, # selected, and file name.

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- 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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- 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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- 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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- 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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Documents

Image Digitization - American Museum of Natural History · 2014-04-24 · Image Digitization Overview The following is an overview of the procedures and workflows used by the Digital