About our images


Basic serial-focus images
Dual zone images
Composite images

Many of our images are serial-focus images, the display of which we developed specifically for this website.[1] Each is not a single image but rather a stack of images captured serially at different focal levels through the specimen or field. These serial-focus images are presented on our web pages to simulate how you would see the specimen or sample in our microscope as you focussed through it.

Basic full serial-focus images

(1) As you move the cursor anywhere horizontally across the image, you simulate moving the focal plane of the microscope away from you (left-to-right cursor movement) or toward you (right-to-left cursor movement). Valves are oriented so that focussing down always moves you away from the external face and toward of the internal face of the valve, regardless of the valve's orientation on the slide

(2) If you move the cursor out of the image, the image freezes with the optical slice currently being displayed.

• Exit via the top or bottom margin of the image, and the image will freeze the optical slice in the stack currently being displayed.

• Exit via the left or right margins, and you will freeze the image on the first or last image, respectively, in the stack.

Try on image on home page.

Dual zone images

We have modified this basic full-serial-focus pattern in many cases:

(1) In some we have constrained the horizontal focal zone to be limited to two zones, each about 10% of the image height, along the top and bottom margins of the image. We generally use this focal-zone structure when we want to

leave the greater portion of the area of the image free for annotations, and

display both ordinary brightfield (upper focal zone) and Hoffman modulation contrast (lower focal zone) images of the same specimen. Each of these focal zones operates exactly the same way as the full-image height zone.

These zones are only marked in the thumbnail image above, but a readily detectable by a change in cursor shape when hovering over them.

(2) In very large (vertically) images we sometimes extend these focal zones to be up to 20% to maintain full user-access to both focal zones from the entire, or most of, the image. In these cases the arrowheads along the right image margin delimiting the focal zones have indicate this.


[1] A little more than a decade ago (c. 2000) David Mann (University of Edinburgh) developed with colleagues a web-usable visual display of serial focus images using a slider external to the image itself and a downloadable set of Fortran programs to run the image rollovers. [At present I am unable to relocate these pages and files on the web.] Inspired by what I saw there and then, I have tried to achieve the same results in our images using simple javascript code intrinsic to the html file, thus foregoing sliders, downloads and installations. Just move the cursor. [RKE]

Composite images

In some images we have co-opted left or right margins of the image focal zone to display a composite image as the cursor moves nears the margin. A composite image is made by splicing together the in-focus parts of each image in the stack. These images are readily apparent when displayed as part of a serial-focus stack, so they are not specifically marked. They do not occur with all image stacks. We have also, on occasion, coopted a portion of a focal zone to display an image not associated with the stack, as on our opening page.

e on images >

Page created 27 February 2015.
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