RE: slide presentation
Hello Dr. Bucana,
I'm a bit surprised that PowerPoint is unable to fulfill your needs but can appreciate your dilemma. When I made slides
for presentations, I used PowerPoint and published the final product to Ektachrome; however, the online presentation
was quite suitable too.
I think some of the problem stems from resizing the image in PowerPoint rather than resizing in a graphics software
program and then placing the intact image in PowerPoint. When I produced composites, I resampled each *.tif file in
Photoshop to the desired final size (ie. dimension and resolution) and then placed the grouping of *.tif files on the
PowerPoint page. If you just place a huge, high resolution image in PowerPoint directly and then resize it, the hidden
attributes of the file remain. In other words, PowerPoint does not eliminate or resample the original image data...it just
doesn't show it; but the data still exists and this contributes to file "bloat." This may be what bogs down your system.
Also, you lose some control over what part of the image is shown and what is hidden if the image is not resampled.
Further slowing down the system is the compression step. The computer/projector must uncompress the image using
the file format's compression algorithm which can take considerable processing time. Also, when you compress the
images, you can lose data. I'll assume you compress the *.tif s using LZW (which is lossless) so you're probably not
losing data in this instance. But if you use another format, it might be a lossy one. This could contribute to some image
Finally, it is very unlikely that any image you scan will appear the same way on a computer screen and on a projector.
Serious color calibration is required since the hardware used to produce the image is so different. A CRT (cathode ray
tube) is sending the image directly to your eye while a projector is sending the image to an opaque screen which is
redirecting by reflection the image to your eye. Calibrating your online image to a projected image can be a daunting
task and may require extensive tweaking.
Also remember that most projectors do a poor job of reproducing the resolution you are accustomed to on a CRT. A
monitor is capable of producing an image at 72 dpi (dots per inch) which, when projected on a screen 30-50 feet away,
is pretty poor. Compare that to a printed image where 300-600 dpi is not uncommon. The advantage of scanning at a
high resolution is that the original scan allows more options when producing viewable media (photo/paper print, CRT,
projector) as well as zooming in on small regions. Unfortunately, projectors cannot fulfill this zoom very well (as far as I
In conclusion, I would recommend resampling the original *.tif images (~100dpi, no compression, reasonable color-not
unlimited color) in a graphics software program (PhotoShop is superb but Paint Shop Pro gets great reviews, too) and
then placing the images into PowerPoint for "final" publication. This offers a reasonable starting point for manageability
5/14/2002 12:03:41 AM, HistoNet Server wrote:
>Date: 13 May 2002 23:36:35 -0500
>From: "Corazon D. Bucana"
>Subject: slide presentation
>Thank you to all who responded to my request for information regarding
>other software for slide presentation. Some of the suggestions include:
>(a) http://www.irfanview.com I downloaded this tonight and I find it very
>easy to use.
>(b) UPresent from http://www.codeblazer.com/products.html I have not
>tried this yet
>(d) using HTML
>(f) Other suggestions deal with increasing the computer RAM and data
>Our projector has a 1024 x768 resolution and we do paste the full image
>onto the Powerpoint page and then adjust the size of the image but the
>problem comes when we try to paste a composite consisting of more than 6
>images. Quite often the images appear washed out - the images were
>captured originally in Tiff format but as I indicated earlier we had to
>compress the file before pasting.
>Thank you all for the information. I will try some of the other
>Corazon D. Bucana, Ph.D.
>Dept. Cancer Biology
>UT M.D.Anderson Cancer Center
>1515 Holcombe Blvd, Box 173
>Houston, Texas 77030
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