-- Philip Best (email)

Projection is a physical phenomenon. Microscopes and telescopes project images onto one's retina (or, today, onto a optical sensor array). Stethoscopes project acoustic vibrations from the patient's skin to the listener's ear. Such magnification has affordances and limitations, just like paper and computers do. There are too many limitations and affordances associated with all the methods of information display to discuss here. I'll concern myself with one limitation of projection: resolution. The maximum resolution of an optical system (lenses and mirrors) is limited by the objective element's diameter.

This resolution limit of an optical system is not the same as the resolution limit of the source image the optical system is magnifying. If the source image is the object (a star, a cell, the head of a pin) then the resolution limit of the source image is zero. If the source image is a representation of the object (on paper, film, or a liquid crystal array) then the resolution limit of the source image is a function of the mechanism that produced the representation. The resolution limit of ink on paper is determined by the machine, the ink, and the paper. The resolution limit of emulsion on film is determined by the grain size of the emulsion. The resolution limit of a liquid crystal display is the number of pixels per inch. Indeed, if, inside projectors, we used large plasma screens with the resolution of the tiny arrays, this wouldn't be an issue. Instead, we magnify the limited information on these tiny arrays a hundred or a thousand times and so resolution is an issue. But the projector isn't the problem. We're not pushing the resolution limit of the glass, we're asking for greater resolution from the imaging array. To improve resolution of projected images: 1) use larger source images (talk to medium-format photographers) so the same resolution will take you further, or 2) use an entirely different technology with inherently higher resolution. Film, while perishable, will probably continue to have higher resolution than its digital competitors.

-- Niels Olson (email)

I have used the 11 x 17 handout folded in half and printed on both sides that Dr. Tufte recommends. But my challenge is to have it viewable as an electronic version suitable for a computer monitor but when the user desires a print version, it is printed in the correct format for duplex 11 x 17 for the handout. Does anyone have any recommendation for a software package (e.g. Adobe) that could allow this kind of scripted command on the document to accomplish the above?

-- Sam Perry (email)

While there are software packages that will let you generate slides and handouts from one document, I think to do so is barking up the wrong tree. As the initial post in this topic posits, the design of printed and projected material is different. To take typographic details as an example, the best font for digitally projected material is an even number of pixels wide and may be a sans serif font such as the well known and much maligned Arial. These fonts have the wrong set for printed material and don't look or read as well as say Helvetica or Gill Sans. And for printed material, a serifed font may be a better choice. Other details such as color choice and contrast with background, are perhaps even more important. The design of handouts and slides are better undertaken as separate tasks than as an integrated document. That said, there are packages for LaTeX (such as beamer) that allow the simultaneous independent design of presentation and printed material that allows the document to generate one or the other depending on a switch in the document. The images are common but the formatting is unique for each form, print or slide. I have used this once or twice but the formatting of the printed document is a compromise to keep the use of the tool simple. Because of the compromised nature of the formatting, I keep returning to the strategy of getting my handout right first then constructing my talk to illustrate the cardinal features of the handout. It takes more time than the integrated document approach but for talks that must be remembered well, I think it's a better strategy.

-- John Walker (email)