Analogue to digital

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This taught session is part of Research Methods also called Workshop 1

Introduction

PRDAScanning 009.jpg

Digitisation of cultural assets such as photographs is now a well established practice. See Paul Goodman's Powerpoint from November 2009 Bradford visit File:DMU Digitisation Session (November 2009).ppt.ppt for some of the main motivations for digitising resources and some of the more important considerations when undertaking this kind of activity.

The preferred formats for archival material change with times and inventions. Floppy disks, film reels of various formats, CD-ROMs, paper prints, online storage… Many archives have film or image material stores in formats that are obsolete and lack the viewing equipment to utilize the sources. Converting formats is expensive and time-consuming – and ultimately a doomed experiment as yet other formats disappear. Right now, we´re in a digital age, and the impulse is for converting analogue material to digital formats. In this session you are introduced to the key principles of digitising archival material including handling, scanning, file saving and naming. You will be expected to apply what you have learned to digitise the material in your selection of archival material for use later in the module.



Through a series of workshop practical activities you will explore two key questions:

  • How can resources be digitised?
  • What is the best way to do it?


Throughout the session, Stuart Wade will be on hand to discuss technical details, give advice and answer questions. At the end of the session, you will be given time to do the exercise, and Stuart will give you feedback, including telling you if your digital project would have passed or failed at the MA level. These two video clips provide an impression of what the workshop sessions are like:

Scanning instruction

Materials handling instruction

Learning outcomes

By the end of this session you will be able to:

  • Decide when to use a scanner or camera to digitise an object.
  • Choose appropriate file types, sizes and resolution.
  • Explain the relationships between "file size", "compression" and "image size".
  • Employ appropriate file naming conventions.
  • Calibrate a scanner and use it to scan print and transparent media.
  • Assess the legal implications of publishing material on the Web.
  • Find copyright holders and copyright free resources.
  • Licence Web publications to control how they are subsequently used by others.
  • Find out if others are breaking the terms of your licence.

Scanner history and technology

StuartWade.gif

from Baiba Tetere's notes:

1920s - the first scanning tests

1957 - "The first image scanner was manufactured under the leadership of Russel Kirsch. This drum scanner was built at the National Bureau of Standards in United States. The scanner was developed in the year 1957, and the first image to be scanned was that of Russel Kirsch's son, Walden. The image was 176 pixels, in terms of resolution, and had a size of 5 square cm. It was a defining moment in the history of the development of image scanners." (paragraph from [ http://www.buzzle.com/articles/history-of-the-image-scanner.html]

Early 1980s - the invention of Drum Scanner which makes use of the Photomultiplier Tubes (PMT), to capture the image.

CCD (charged coupled device)chip is the most widely used sensor format these days. More about CCD chip at [ http://www.cctvconsult.com/pages/ccd.htm ]


Workshop practicals

You will be introduced to the history of scanning, the basic mechanism of scanners and the principles of effective scanning through a series of practical demonstrations and hands on activities.

The scanning process

Open Photoshop

File Import – Scanner = Epson Mode = professional mode Preview


Adjust settings for scanning: Document type/ File type/ Image type (colour / b/w/)/ Resolution/ Document size (Always scan in colour for our practice)

Print screen colourslide scan settings.png


Image adjustments after scanning: Maybe choose to make it a slightly flatter image than a high contrast image to keep the most information


Image – Image adjustments – Levels: You can adjust the levels to obtain the most amount of information in the darkest areas and the lightest areas

Print screen - out of place 2 Levels.png


Scanning Daguerreotypes

MichaelFaraday.jpg

Anon. Portrait of Michael Faraday. Daguerreotype. c.1848 Source: National Media Museum. http://www.nationalmediamuseum.org.uk/collections/Collection_Detail.asp?ItemID=47&SectionID=3&index=7


The following advice was posted by Joe Bauman to the Photohistory mail list on 20/08/10.

Hi, I take no responsibility for any damage you may do to your dags, but I will tell you how I scan them.

I'm a member of the photographic history Internet discussion group and of the Daguerreian Society. I have safely scanned many daguerreotypes with flatbed scanners.

The most important thing to remember is that nothing must touch the actual face of the daguerreotype, because the slightest fingerprint will be there permanently. If you were to try to brush off dust, it would leave streaks. Anyway, when scanning a naked dag plate, I simply place pieces of paper, or playing cards, on the glass of the flatbed. The paper or cardboard or cards go to support the corners of the dag. I stack these supports a bit to make sure that the dag's surface isn't bent or sagging in the middle, so that it does not touch the surface of the glass. I keep the scanner's lid open when I scan. Then I replace the dag carefully in its sandwich of mat and glass, reseal it, and put it back in its case. That makes the clearest copy because there's no dag cover glass in the way with its own streaks, bubbles or dust. But I also can make a perfectly good scan by keeping the dag in the "sandwich" and just lying that on the flatbed. If the preserver is over the cover glass, it will keep the cover glass off the scanner surface; if not, I put paper or cardboard, as before, between the two sheets of glass so I don't get interference patterns from where the pieces of glass were touching. Best wishes, Joe

Activity: Digitising resources

Pair up with someone and use your wiki pages to document your activity:

You will be given two sorts of objects to be digitised, printed photographs and glass plate negatives. These are the most common types of objects you will encounter for digitisation projects.

Digitise both objects, and produce two files from each object (you'll have then four files total in the end):

  • One suitable for archiving/printing
  • One suitable for web use

Files need to be named to identify:

  • who scanned them
  • title of the image
  • the intended use of the file

You will need to consult as a whole group to confirm your naming conventions.

Save your images meant for the web to your wiki pages and label them. Save your files for archiving/printing to a server, the name of which will be given to you on the day.

Stuart will provide each of you with feedback on this exercise. Although it does NOT count in your final marks for this module, Stuart will give you an indication of whether your digital work would pass or fail at the MA level.

Object handling

- Have clean hands – some places prefer white gloves

- When getting something out of a box, don´t fish around for the corners, but tip the box, keeping your hand on top of the object inside so you can get a good grip. Don´t tip boxes with glass negs, but be aware of the sharp edges when getting them out of boxes. Grab a firm hold of two sides of one corner – don´t use nails to separate but take out however many comes and use finger padding to separate later.

- Always handle objects with two hands, and always over a table (or mat) surface, don´t wave it one-handedly above the floor


Some useful tips

Always scan in colour, nothing is really black and white – scan to a high resolution and resave in lower res if and when needed. There is an argument in keeping the scans a bit flat rather than contrasty, as this keeps more of the visual information.

When scanning prints, a 50% greycard can be placed on top, when scanning glass negs a sheet of acetate should be placed on and under (to avoid scratching the scanner glass). When scanning negative film or plates, it´s important to remember that “positive” scans the object, whereas “black and white” automatically reverts the image to a positive.

Keep the colour channel to RGB, CMYK is for the pro printing industry. Info, ex biro marks on a print, can be taken away by going into the individual colour channels and subtracting. A “moirée” pattern often appears when scanning printed material, this can often be helped by using the “descreening” option, by scanning in a higher res and resaving, or by playing with different photoshop filters like dust n scratch.

Some objects, like daguerrotypes, can´t be scanned easily and are best photographed,(but see "scanning daguerrotypes" above).

Scanner vs. Camera

Object characteristics Scanner Camera
Flat/2D object Yes Yes
3D No No
Light sensitive No Yes
Fragile No Yes
Abrasive/sharp edged Yes (With protection for scanner glass) Yes
Transparency Yes Yes (Requires adequate light box/backlight)
Large (> A4/A3) Specialist scanning only Yes (Subject to space/setup)


File type, size, resolution

File type governs image quality:

TIFF – Uncompressed; Lossless. Yields full data. Large files (relative).

JPEG – Compressed; Lossy. Allows for smaller files – especially important for Web use.


Image size constrains uses:

Digital image size is determined by pixel dimensions – irrespective of resolution (dpi/ppi) or document size (width x height).


Resolution is an expression of display characteristics:

An image on screen is displayed at a resolution determined by the monitor’s capacities – historically 72dpi (Apple) or 96dpi (Windows) – independent of the image capture resolution.

Digitally printed images are generally printed at a resolution of 300dpi at whatever desired print size. 300dpi is selected because it represents the coarsest resolution at which individual dots are not discernible by unaided human vision.


THUS:

A scanned image, from a print 10”x8”, captured at varying resolutions output sizes, will generate digital images with the following characteristics:

Scan resolution Scan ratio Image size Pixel dimensions File size @ 24-bit (uncompressed)
300dpi 100% 10”x8” 3000 x 2400 20.6Mb
150dpi 100% 10”x8” 1500 x 1200 5.15Mb
150dpi 200% 20”x16” 3000 x 2400 20.6Mb
200dpi 200% 20”x16” 4000 x 3200 38.62Mb



Adobe Photoshop and Epson Scan settings:


Image size.jpg Epson scan2.jpg


Epson scan.jpg Epson scan3.jpg


Digitising Exercise

Guidelines for scan settings:

Archive master – Prints and large negatives: TIFF (uncompressed/lossless format) 300dpi @ 100%as standard; 600dpi to allow for enlargement

Web: JPEG 72-100dpi; Sized appropriately for screen viewing – 1000px x 1000px; 50% compression

Print: JPEG (uncompressed/lossless format) 300dpi as standard; 600dpi to allow for enlargement


Object 1:

Glass slide negative. Unknown photographer – Mann Collection; unknown date.


Mw09 sky0001 web.jpg


Scanned between acetate sheets to protect slide and scanner glass.


Scan Resolution and format

For archive: 600dpi at 100% to allow reproduction/printing at a range of sizes, including moderate enlargement.


Archive file saved as TIFF; Web file as jpeg following naming protocol agreed with colleagues:

initials_year_imagename[seq0001]_imageuse.ext
eg.dh09_sky0001_archive.tif
dh09_sky0001_web.jpg


Scanned file resized in Photoshop to produce web jpeg file at 72dpi.


Scan options for transparencies in Epson Scan include: Positive, Colour Negative and B&W negative.

Colour negative - software produces a blue image to correct for film mask, which is absent in B&W negative.

B & W Negative - automatically converts to positive image. May not be appropriate to archival record of actual object since conversion introduces additional stage of image interpretation.

Positive film scan - Selected to scan negative to negative

Scan executed in 24-bit colour to take account of any colouring in glass or negative image. (Ideally, all relevant devices – scanner, monitor and printer – should be colour calibrated to ensure colour accuracy. Could scan with colour registration strip to calibrate.

Negative density quite thin. Scan adjusted to accommodate - ensuring all highlights and shadow tones incorporated - but resulting positive image still quite dark.

Marquee adjusted to include the whole of the plate – to encompass the object as a whole, not only the image.

Scan inverted to positive image in Photoshop. Image density adjusted using the Levels and/or Curves. Particular attention paid to retaining shadow detail and highlights.

Colour space sRGB.

Files saved for both negative and positive images.

Reflections on this activity

Please answer the following questions on your wiki pages and post a link to your answers here:


How appropriate is your choice of file format, resolution and size?

What do you need to take into account when making these decisions?

What does "size" mean in relation to a digital image?

NB Jacky Longstaff's slides File:Analogue to Digital Oct 10.ppt are a good example of how to make useful notes. They reproduce the scanned image and describe how it was created in enough detail that someone else could follow them and recreate the same image. This is very similar to the methodical approach taken by some photographers, eg. Paul Strand(Stephen)


Follow up work

Digitise your selection of archive material and add the digital image information to your catalogue spreadsheet.





Follow this link to the PRDA Contents or Research Methods Contents page to return to the module contents.

Back to the MA: Photographic History Main Page to return to the Course contents.