UK ARCHIVING. preserving our heritage. 4 Bankhead Medway, Edinburgh, EH11 4BY. Microfilm Quality Control Inspection

Transcription

1 UK ARCHIVING preserving our heritage 4 Bankhead Medway, Edinburgh, EH11 4BY Tel: Fax: Microfilm Quality Control Inspection

2 This guide has been written to assist staff in the quality control inspection of microfilm. It is not a definitive document and as such is subject to change/review/revision from time to time. All information supplied is for reference and should you require more information please use the NPO guide, RLG poster, British Standards and the supervisor for your area to assist you when difficulties arise. If you feel that there should be information added to this guide, please put your suggestion forward and they will be discussed with all staff, if of relevance they will be included in the next draft. This guide for your reference, please use it. UK Archiving 4Bankhead Medway, Edinburgh, EH11 4BY Phone Fax Draft 3: 11 th December 2006

3 Chapter 1 Introduction Quality Control Outcomes 1. Inspect completed microfilms to determine compliance with standards. 2. Make a technical check of completed microforms to determine correct processing, resolution, density and film base. 3. Make a visual check of completed microforms to determine completeness, image legibility and compliance with specifications required. 4. Recording of quality control inspection details. General Information Check of the final product is especially important in preservation microfilming where the aim is to preserve knowledge and cultural heritage for the benefit of future generations. Any errors or omissions will limit the usefulness and authenticity of the microfilm. If the original material has deteriorated badly, it may be impossible to copy it again in the future. Apart from the preservation issues, quality control makes sense from an economic point of view, in checking that there is value for money. After investing all the time, knowledge, skills and work in preparing, filming, processing and duplication microfilm, it makes sense to check that the final product meets the required standards. In essence, a quality inspection program is the test of an organisation s commitment to preservation microfilming. So, whether the microforms are produced by a separate microfilming organisation, or in-house, a regular quality control inspection program should be established. Inspection should be carried out in a logical, structured manner, with specific levels and criteria established before starting the inspection process. Work Area and Equipment It is useful to have a separate area set aside for quality checking. Enough space is needed around the area for staff to look at the microfilms as well as the original documents (if required). Appropriate equipment for quality checking includes. 1. Clean white cotton gloves 2. Pair of film rewinds mounted on a level working surface 3. Light box placed or built-in between the rewinds (or in densitometer) 4. Eye loupe 5. Microscope 6. Densitometer 7. Microfilm Reader 8. Microfiche Reader (if required) 1

4 Technical Inspection of Microfilm: Criteria Use a densitometer to check that film density is within specifications Check the resolution test chart to confirm that the specified level of resolution has been achieved (please be advised that resolution is subjective to eyesight and can vary from person to person, if you are unsure that the resolution of the master film has been achieved ask another member of staff to check the resolution, without telling them what your findings are) Microfilm is visually checked for any defects which will cause the film to fail the Quality check 2

5 Density Chapter 2 Density Inspection The type of film, the exposure levels and how the film is processed influences density. Many preservation-microfilming projects specify minimum density ranges according to the contrast and types of material. Level of contrast Density tests measure the level of contrast achieved between the dark and light areas on the film. On negative films the background density or maximum density (Dmax) is the dark part of the image and the minimum density (Dmin) is the clear part. Positive film is measure for Dmin only. The NPO Guide to Microfilming specifies that the following readings should be taken on every roll of film. Generation Maximum (Dmax) Density Minimum (Dmin) Density Master Negative Yes Yes Working Negative Yes Yes Working Positive No Yes Taking a Density Reading Taking a density reading from a master negative involves the following steps: Step Comments 1. Use a densitometer (calibrated) Use a densitometer which has been properly calibrated using the calibration strip supplied with the densitometer 2. Identify points for background density readings Select the background density readings (Dmax) from a part of the page without text or illustrations (this is usually the dark part of the image area) Avoid taking readings from inner or outer margins as pages may be discoloured around the edges (this may be unavoidable in some films) 3. Take at least 8 density readings Take a minimum of 8 Dmax readings throughout the roll of film, record your results on the QC sheet Ensuring a density range of no more than 0.20 across each roll of film. (E.g. Min Density Max Density 1.30) 4. Average the readings Add all the readings together and divide by 8 to give you the average reading throughout the film, record result on QC sheet 3

6 5. Take 1 Dmin reading Select the clear area between frames to obtain the Dmin reading, record your result on the QC sheet This reading is also known as base fog reading Density Levels The NPO guide specifies certain background density levels for different types of materials. These are shown in the table below: Classification Description of Documents Background Density Group 1 High quality, high contrast printed books, periodicals and black typing (usually current material) (UK Archiving Aim Standard) ( ) Group 2 Fine-line originals, black opaque pencil writing, and documents with small, high contrast printing (this will include current newspapers) (UK archiving Aim Standard) ( ) Group 3 Pencil and ink drawings, faded printing and very small printing such as footnotes at the bottom of a printed page (this will include older newspapers, although in some case you will have to use group 2) (UK Archiving Aim Standard) ( ) Group 4 Low Contrast manuscripts and illustrations, graph paper with feint lines; letters typed with worn ribbon; poorly printed, pale or coloured documents (UK Archiving Aim Standard) ( ) Group 5 Poor contrast documents (UK Archiving Aim Standard) ( ) These levels are only a guide We aim to achieve the center point in these levels and try to avoid a variance of less/more than the.10 above and below (allowing for the 0.20 variance on a given page of material). Please be aware that in certain circumstances the film may fall out with these levels and a reason for the variance given. In practice, the recommended density level is a guide only. Many originals are far from ideal, with poor contrast, fine lines, mixture of text types, mixture of background colours and print quality. Simply specifying a high background density may produce an image, which may not be legible. This is one reason why preservation microfilming has been described as an art, as well as a science. Other problems, which materials have, are, a number of contrast levels on one page (e.g. text and photographs) and these may require multiple exposure at different settings. Before filming a step test should have been carried out to determine the best density that suits the material being filmed. It is best practice to check with the camera operator if there is a variation to the above table for a given reason. With time and knowledge it is possible for some operators to be able to determine in advance if material needs to fall out-with the classifications listed above, example: 4

7 Case Study: Group 4: Manuscript original material is only 25% readable due to very dark patches across the page, in some instances it completely unreadable. This had been caused by various factors dirt, poor conditions, water damage etc. Solution: The material was filmed at a higher density level in this case , the master is visibly too dark to view properly on a microfilm reader, but the resultant positive produced gave a clear 95% readable image. This is what we are aiming for, to be able to reproduce material that would otherwise be deemed unfit for the use it was intended. Uniform density target The uniform density target is another of the technical targets that are quality-checked. This target is used to check how well the camera lamps are balanced. The target is nothing more than a white sheet of card or heavy paper. This target is filmed twice at the same exposure level (not necessarily at the exposure level for the material) immediately before the start and end targets. Ideally the target should be the same size as the actual frame to give a more accurate measurement. It should be noted however with camera s that have low level, cool lighting attached, that light balance is a matter of filtration and diffusion not the angle of the bulbs as with older light sources. It should be noted however that low level lighting comes with diffusers fitted and often a light reflector clipped to the middle of the lamps. In some instances the reflector has to be removed to achieve a balanced background density. This is purely dependent on the type of lighting system you use. After processing, the density readings of both uniform density targets are compared for any significant variation, which might indicate lighting, camera or processing problems. Feature of uniform density target Areas to be tested Details All four corners plus the centre (note you may find that the centre reading is slightly higher than the corners) Generation to be tested Master Negative Levels Density of all areas tested should lie between Differences Density of all five areas area s should not be more than 0.10 in the density range Area to be tested Within the circles drawn on the uniform density target 5

8 Chapter 3 Resolution Inspecting Resolution Resolution is the degree to which fine details can be distinguished. The higher the resolution, the finer the detail reproduced. The resolution test chart appears in the start sequence. The resolution targets are five individual charts. One is in the centre of the frame; the other four are placed in the corners so that they correspond to the corners of the largest documents being filmed. Each pattern on the resolution chart has a rating. Sample It should be noted that there are several different types of resolution chart available, the standards states that 5 individual charts be used to ensure a more accurate placement of the targets. The resolution chart used is: PM-1 3½ x4 Photographic Microcopy Target, NBS 1010a ANSI/ISO #2 equivalent. Calculating Resolution The test patterns on ISO resolution chart #2 should be examined with a microscope, to determine the smallest pattern that can be resolved, i.e. the smallest in which all five individual lines in the pattern can be clearly distinguished in both directions. All five test charts must be read noting the smallest pattern which can be read for each. Resolution is the worst reading which is obtained from the five results commonly in the corner patches. (source: NPO Guide to Preservation Microfilming BS ISO 3334:2006 Micrographics ISO resolution test chart No.2 Description and Use ) Steps Comments and Examples 1. Inspect under a microscope Inspect the filmed image of the resolution chart under a microscope Handle film carefully with cotton gloves Lift and move the film do not push across microscope plain as this will scratch the image 2. Examine pairs of line patterns and move from larger to smaller Ensure that both horizontal = and vertical lines can be clearly distinguished Keep on looking down the patterns to the smallest line pairs, it is possible to clearly distinguish (1.0 largest, 18 smallest) 3. Select the smallest pair of line patterns that can be resolved The fine lines should be clearly distinguishable in both directions 4. Record Line Pairs per Millimetre (LPM) Record your results on the QC sheet provided for the film 6

9 5. Check all 5 charts All five charts must be checked in this manner to determine which chart has the smallest pattern resolvable (this would be the worst one readable) 6. Calculate the resolution Using a calculator to determine the resolution of the film. I.e. reduction ration x lpm Example: Smallest pattern resolves = 6.3 Reduction Ratio used = 18x Resolution outcome = 6.3 x 18 = 113.4lpm 7. Record resolution Record your results on the QC sheet provided for the film Guide to British Standards for Resolution The following is the standard for LPM at a given reduction ratio: RR X LP = LPM 9 x 9.0 = 81 lpm 10 x 9.0 = 90 lpm 11 x 8.0 = 88 lpm 12 x 8.0 = 96 lpm 13 x 8.0 = 104 lpm 14 x 7.1 = 99.4 lpm 15 x 7.1 = lpm 16 x 7.1 (6.3) = lpm 17 x 6.3 = lpm 18 x 6.3 = lpm 19 x 6.3 (5.6) = lpm 20 x 5.6 = 112 lpm 21 x 5.6 = lpm 22 x 5.6 = lpm 23 x 5.0 = 115 lpm 24 x 5.0 (4.3) = 120 lpm 25 x 4.5 (4.0) = lpm 7

10 Resolution Levels In preservation microfilming a minimum level of resolution is often specified. The following are levels that are commonly achieved, but will vary from camera to camera and chart to chart. Generation Master Negative Recommended Resolution 100lpm minimum Working Negative Should not be more than one level lower than the master generation Working Positive Should not be more than one level lower than the working negative. It is common in most place that the working positive is not tested as it is generally the access copy 8

11 Chapter 4 Visual Inspection Unless the microfilm is a complete, accurate and legible copy of the original material, it fails to meet preservation requirements, even if its technical quality is excellent. If the microfilm meets all the technical standards, it should be visually checked for defects. This involves placing the film on a reader and inspecting it, frame-by-frame. This should be compared with the original material (if available). How many and how much should be checked? Experience suggests that the only reliable method of confirming that the microfilm is a complete and accurate record is to carry out a frame-by-frame inspection of the Master Negative. As many organisations do not have the resources to do frame-by-frame checking, the question of how many should be checked becomes an individual risk management issue. It is our opinion that every film should be checked to guarantee the preservation microfilm. Checking for completeness and compliance to standards The film should be checked for completeness, legibility, physical condition and compliance with the standards. It should be a complete, accurate and legible copy of the original material. The following is a typical list of feature to check in a detailed visual inspection. Always refer to the RLG poster for a full list of defects if required Check for Completeness Comments Original Material has been filmed in its entirety There are no missing pages/issues Information has not been lost due to gutter shadow Targets (see examples at end of manual) All of the Technical and bibliographic detail targets have been filmed All of the targets appear correctly and in the correct order All of the targets are in the correct orientation for the film Alignment The Image is aligned correctly within the frame, with no more than a 5 skew from the vertical Orientation Image orientation is according to specification e.g. single or double frame, Broadsheet or Tabloid Image orientation is according to specification for digitisation Reduction Ratio The reduction ratio used nearly fills the frame, with all the edges of the document visible Legibility All of the information is easy to read (regardless of resolution and density levels) Density There are no major variations in density Photographs or other features are neither to light nor too dark Multiple exposure are used to film originals with variations in density Focus There are no blurred images especially near splices (this is relevant to the duplicate copy only) 9

12 Foreign objects There are no additional objects in the images e.g. operators hands, tape, pencils etc Fogging There is no fogging or extra light which may cloud the image Splicing Only the master has been spliced Splices have been made using an ultrasonic splicer Adjacent frames are not scratched or blurred There are no more than 6 splices per film There are no splices between the technical target and the first ten frames of the material being filmed Defective frames have been removed/replaced where necessary At least two pages before and after the page being refilmed are included in the retake Scratching The film is free from scratching (see RLG poster for what is acceptable and unacceptable) Marks/Abrasions (Physical condition) The film is free from blemishes, dust, fingerprints, water spots and other defects Quality Check Inspection Record Any quality problems that have been identified should be recorded systematically. Clear and accurate records of problems will help in the next stage of deciding on the actions to take. Most organisations create their own quality inspection record sheets. We use a job record envelope, which follows the film through the entire process from preparation to duplication. All information should be recorded fully on the envelope to give the camera operator a clear set of instruction to rectify any errors there may be. Problems: causes and actions Once problems have been identified, the next stage is identifying the causes. This will help in determining what to do next. The original text should always be checked in this process. For example, a stain on the original. No further action can be taken in this case. In other cases where the cause is likely to be a problem with the equipment or the operator, further action needs to be taken to prevent the problem recurring. If any of the problems are found within the inspection list above, the film needs to be sent back to have the problems rectified, spliced in and rechecked before in can be considered as being to preservation standards. 10

13 Chapter 4 Summary Unless the microfilm is a complete, accurate and legible copy of the original material, it fails to meet the preservation requirements, even if its technical quality is excellent. Check the resolution and density of every roll of film. Every roll of film produced should be checked in its entirety. All relevant information should be recorded to give a complete and accurate assessment of the film being checked. Any retakes are checked before duplication commences You are aware of all the standards and other relevant information required to carry out quality control You have all the equipment and associated materials to carry out quality control Cotton gloves must be worn when handling microfilm You must handle microfilm gently and with care to avoid causing damaged 11

14 Chapter 5 Appendix 1. Example of Quality Assurance Sheets 2. Example of Start Sequence 3. Example of Bibliographic Targets 4. Example of Copyright Statement 12

15 2 Examples of Targets used In the Start Sequence All the boards shown in this example form part of the Start Sequence. Along with these there are the standards ISO targets that are used. The following is a typical start sequence layout. Start Filmed by Copyright Title Board (bibliographic target) Best Copy Available Reel Contents Any other as needed targets Resolution Target Material End Board End of Reel Please be aware that when filming of material that is owned under copyright by the client, they may supply their own start sequence. The sequence should be filmed in the order that they have specified. 13

16 3 Dumfries Dumfries & Galloway Standard (Wed) 14

17 3 REEL CONTENTS 2342 Start Date: January 4 th 2005 END DATE: June 29 th 2005 FILMED: REDUCTION: FILM SIZE: 35 mm FRAME COUNT: FILMER: PRESSMARK:

18 3 END OF REEL PLEASE REWIND Dumfries & Galloway Standard (Wed) Dumfries 16

19 4 COPYRIGHT STATEMENT This film has been supplied by UK Archiving Ltd a division of SNMU Ltd, 4 Bankhead Medway, Edinburgh EH11 4BY, on the condition that neither it nor any part of it is further reproduced, copied, digitized, processed or made available in any form or media without the express written permission of the SNMU Ltd. Please note that the material filmed has itself copyright and similar rights, and therefore the permission of the owners of that copyright will also be required for such reproduction. Under certain conditions specified by law, libraries and archives are authorized to furnish private users with a photocopy or other reproduction, on the condition that the photocopy or reproduction is not to be used for any purpose other than private study, scholarship, or research for non-commercial purposes, Only limited copies are available under these provisions and no other uses are permitted without written permission. Any use of this film without these permissions and/or in excess of the Fair use provisions may result in prosecution for copyright infringement and/or a claim for damages. 17

20 MICROFILMED BY UK ARCHIVING LTD 4 BANKHEAD MEDWAY EDINBURGH EH11 4BY