Scanning fibre prints for digital projection
Until recently, when lecturing, I showed Scala copy slides of my B&W fibre prints. With the demise of Scala and the increasing difficulty in finding optical slide projectors at out of town meetings, I must succumb to a digital solution.
I have access to an Epson 1000XL flatbed scanner and hence can scan 11 X 14" original prints. I can then insert the scanned files into a powerpoint slideshow for digital projection. I speak to groups of up to 450 people and hence the projected size will have to be BIG.
Given my lack of experience with digital scans, I have a simple question. What is the best file type (jpeg, pdf etc) to insert into a powepoint presentation, and at what resolution or file size should the prints be scanned?
I thank you in advance for helping me to make the leap...
With powerpoint I think you will want to work with jpegs. I have had so-so success with pdfs.
The optimal resolution will depend a lot on your projector. If you are going to be doing this a lot, then it may be worthwhile to invest in your own high quality projector. Then you can match your digital files to the projector... they are definitely not created equal.
Another solution may be to scan and make your own overhead transparencies. I have recently started working with pictorico transparency film and I suspect that it may be the best way to get a large image on a screen. A well-made 8x10 overhead can be quite a stunner.
Another (perhaps overkill) solution would be to get dr5 processing, which should rival or exceed scala for many applications. I have been meaning to try that myself.
The file you end up with should be 72 dpi jpegs.
72dpi is screen resolution & that's basically what you will be doing - projecting data on a screen. Any file bigger than 72 dpi jpeg will just be overkill - you won't see the quality on the screen & it might slow down the application.
There may be some advantage to scanning at a higher quality & then downrezzing to the final size.
If you are used to showing optical slides you might want to run a test on this system first. At the place where I teach they put in data projectors & I made up some new shows in Powerpoint to try it out. After doing this for a year I intend to go back to optical slide showings. The data slides always look a bit soft & there are all sorts of calibration issues with colour images. May not be a problem with you if you are just showing B&W images however.
I don't think it's helpful to think in terms of dpi. Just find out what size the projector can handle (e.g. 800x600 or 1280x720 etc.) and size to that.
Very few digital projectors are designed for a colour space optimized for fine art reproduction. Some projectors might have an RGBs setting, but these are just approximations. LCD projectors usually have over saturated colours. DLP projectors tend to have an odd colour space optimized for brightness.
High quality overhead transparencies made with good ink jet materials might be the only way to get a consistent result as you travel from place to place.
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If you have access to a flatbed scanner then that is the best way to convert your pictures for this application. I would use tiff files for storage, but most projectors, or rather the software they use require jpeg files, so you will need to have these on disk too. As has been said the dpi size is irrelevant for this application, it is the image pixel size that is important, so again store your jpeg images in several pixel sizes, the same sizes as computer screen displays as Keith suggests. You will then be able to select those that accord with the projector on offer. The colour output, and picture quality is about equal to a computer screen display, that is to say, not good; but to the average audience conditioned to accept t.v. screen quality it will be acceptable. It may be worth considering displaying some of your prints for viewing after your talk, so that the quality may be enjoyed by those of your audience that may be able to appreciate them.
DPI doesn't mean anything applied to output on a pixel based display device such as a computer monitor or projector. For example: I scan an 8x10 inch negative at 600 DPI producing a 4,800 x 6,000 pixel file. If I set the print output at 300 DPI, the file will produce a 16x20 inch print. However, whatever the DPI is set to, the file is exactly the same on screen. It is still 4,800 x 6,000 pixels in size whether printed at 150 DPI (32x40 inch print) or 600 DPI (8x10 inch print).
Hope this helps,
Last edited by Tom Kershaw; 12-27-2006 at 10:19 AM. Click to view previous post history.
Reason: Edited for clarity
Thank-you very much for the helpful replies.
I will scan at several resolutions, and I now understand that the digital projector output is roughly screen resolution (i.e. a fixed number of pixels Length x Width) and hence low resolution. Large file sizes are not needed for projection. I will insert jpegs into powerpoint.
Most conferences have dedicated computers at the podium (with the projector drivers I assume) into which one inserts one's memory key (USB memory stick) that contains your powerpoint presentation.
Though I make heavy use of photos in my talks, I lecture about a topic that is unrelated to photography. My audience is interested in the stories that my photos depict, and they are not usually a 'photo audience'. I sometimes have the opportunity to display large fibre prints made from my 4 X 5 negs, and most people are seeing large format work for the first time.