Notes of potential interest to instructors interested in image capture or using the WWW for teaching

The production of these on-line course materials was partially funded by The University of Wisconsin-Madison. The Division of Instructional Technology asked us to record our experiences so that others might benefit from our mistakes and discoveries.

(1) How to capture high-resolution color images from objects ranging from a few microns to ~15 cm in diameter:

(i) Single chip color CCD cameras do not provide acceptable resolution.

(ii) Although three chip color CCD cameras would probably provide acceptable resolution, they cost approximately an order of magnitude more than monochrome models.

A diagram of our set up will eventually be available.

The procedure we use is as follows:

  1. Using NIH Image (or similar software), start capturing. This provides a real-time image on the computer screen, allowing focus and positioning of the sample. Lighting of the sample is currently achieved using a pair of fiber optic lights. This system probably could be improved significantly - suggestions are welcome. All image capture is performed with the room lights off to avoid spurious reflections.

  2. The color images are gathered in 3 passes. Hold the red filter (mounted in some type of holder; we use a cardboard holder that resembles a slide frame) under the camera lens. Select 'Stop Capturing'. This immediately results in a captured image. For simplicity (see below) this image is saved as a TIFF? file named 'r' (without the quotation marks). Repeat for green (save as 'g') and blue (save as 'b').

  3. Go to Photoshop (we used version 3.01, the commands should be the same for version 2.5). Open all three filtered images. Under 'Window' select 'Palettes', 'Show Channels', `Merge Channels'. Then select 'RGB' and OK. (If you named your images 'r', 'g', 'b', as above, the correct filtered images should be assigned to the correct channels. The resulting merged image may need to be corrected for brightness/contrast. It is unlikely, in our experience, that the color will have to be modified.

    The sequence of opening the r, g, b images followed by the series of menu options becomes very tedious. It is possible to automate these steps using a macro approach. We did this using a program called Photomatic 2.0 (recently released as freeware). Once this 'macro' is defined, the reconstructed color image can be created by selecting the appropriate routine from under the `Record' menu, option `Play'.

  4. Save as a JPEG document. We use the high quality option. For line drawings that have been modified in Photoshop, save as a GIF file.

(2) Using the captured images:

Insert call outs for figures in text. The text can be written in Microsoft word, saved as text only with line breaks, copied to the appropriate directory with the images (public_html on our UNIX server), and translated to html markup language using the command:

txt2html <"txtfile.txt"> txtfile.html

The file will have to be tidied up, to optimize formatting.

In some cases, in-line images are required. These should be GIF files. It is essential that the file size is small, as they load over the web slowly. The in-line GIF files in the menu page of our document are each about 20K. These were created from ~100 K jpeg files in the following manner:

(3) Web site searches were done using standard web browsing programs.

For the most part, we used `Lycos'.

(4) How we will use the www document in classroom teaching.

A format for the lecture notes has been selected to allow use of the outline for each lecture in the classroom. To ensure that the more detailed information and explanations are available (without cluttering the outlines) we have moved wordy sections to another level linked by active text.

(5) On-line test taking.

We do not anticipate using on-line examinations immediately. However, we have provided trial examinations on-line. These incorporate a feedback mechanism, so that the students learn where the flaws in their understanding lie. The format of the two on-line tests is such that the tests can be taken without immediate feedback - the student receives a score indicating how they did ( x questions right out of y taken; information regarding which questions were answered incorrectly is also available) - or with direct feedback, the incorrect answer results in an immediate link to the part of the notes that explains the correct answer.

The on-line tests are password protected. For more information, contact us using the form on the introduction page.

We are currently investigating the possibility of offering the course by correspondence at some time in the future. Feedback on how much demand for such an option there might be would be appreciated.

Final comment. We gladly share our experiences and would appreciate any comments, feedback, and suggestions.

Thanking you,