5 Guidelines for Success in Image Capture
This project has demonstrated that it is important to attempt to
maximise spatial resolution, colour quality and contrast ratio
in image capture regardless of medium or system. Distinctions
arise between media in the ways of achieving optimal quality in
these areas, but as ideals to be aimed at they are standard to
all media. The values obtained for these three criteria are the
combined product of the effects imposed by the choice of
equipment for capture and manipulation, and the expertise of the
Three main skills areas are indicated for the capture of images:
The same skills are relevant for the post-digitisation
manipulation of images and their incorporation into computer
assisted learning software packages, although it has not been the
remit of this report to consider that stage. On the basis of the
results reported the following guidelines have been drawn up to
assist staff capture high quality images for use in multimedia
Selection of Source material
The first requirement is to select high quality source material
Successful capture depends on the operator having good
photographic skills and an awareness of lighting techniques.
Analogue Choices 1 (35mm Slide, 35mm Negative, Colour Print)
In some photographic areas there is a trade-off between
- Slides which give faithful colour but no opportunity for
manipulation of colour and contrast ratio until after
- Negatives plus prints which allow more control of colour and
contrast ratio before and after digitisation, but require a
reference (such as the Grey Scale chart or the original source
material) for accurate reproduction
Analogue Choices 2 (Rostrum Camera, Still Video, Videotape frame)
Beyond photography, choices for analogue capture require some
familiarity with video operations. These considerations are not
intended to put off inexperienced lecturers who wish to process
images - rather they indicate that an operator who gains
experience processing images regularly should produce higher
- Rostrum Camera
- Immediate access to captured image. Easy to adjust the quality
of the image at time of capture. High quality colour. Superior
contrast ratio. No recurrent costs.
- Generally poorer resolution than scanner. Re-sizing may require
recapture. Needs digitiser board to capture image.
- Still Video and Videotape frame
- Speed of access. Portability
- Overall quality (resolution, colour, contrast
ratio) poor compared with other media.
Digital Choices: (PhotoCD, Digitiser Board, Scanner)
Familiarity with image capture skills are an asset, specifically
familiarity with digitisation software.
Taking account of these guidelines the preferred paths for
capture of specific classes of image were as follows:
- 5 grades of resolution, allowing effective zoom to detail
without return to original image. Excellent resolution colour,
contrast ratio. Excellent results with slides or negatives, but
negatives easier for operator because of inherent flexibility.
- Loss of control for user. Takes longer. Recurrent cost per image.
Requires slides or negatives, no direct capture of source material.
- Digitiser Board Pros and Cons as per Rostrum Camera.
- Generally superior resolution to rostrum camera. Most
straightforward to use. Fast.
- Colour generally poorer than rostrum camera. Inferior contrast ratio.
- Image - Microscope - Video Rostrum Camera - Digitiser Board
- 3 dimensional subjects using natural or artificial light
- Image - Slide/Negative - PhotoCD
- Image - Video Rostrum Camera - Digitiser Board
- Flat Art
- Image- Slide/Negative - PhotoCD