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Spectral Selectivity page
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Hollis Bewley and I have put up a page on Spectral Selectivity with
topics that might be of interest to people using this list. This page
describes ways to combine conventional "pre exposure" color filtering
and film selection with digital imaging "post exposure" masking of
images using raster ops to select out portions of spectrum. These pages
address creation of pseudo color images and 3 component false color
images using selected portions of the spectrum. We hope to expand these
pages with new topics and further applications in the future. You can
look at the page at Philip Greenspun's MIT Photo Net site:
www.photo.net/photo/edscott/spectsel.htm
Since this is a brand new page, there may be some mistakes and we would
appreciate hearing about anything you notice. We would also welcome a
chance to look at digital copies of sets of images done using these
techniques and might want to put a few up. If you are unfamiliar with
the use of digital imaging rasters ops such Photoshop's combine and
apply modes, Hollis will be doing a tutorial page in the near future.
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<H1>Spectral Selectivity</H1>
<ADDRESS>
<H4>by Ed Scott <SMALL><A HREF="mailto:dotted.dog@xxxxxxxxxxxxxxxx">dotted.dog@xxxxxxxxxxxxxxxx</A></SMALL></H4>
<H4>and Hollis Bewley <SMALL><A HREF="mailto:hbewley@xxxxxxx">hbewley@xxxxxxx</A></SMALL></H4>
</ADDRESS>
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<H3><IMG HEIGHT=15 WIDTH=16 SRC="spectptr.gif"> Spectral Selectivity</H3>
Spectral selectivity is a technique for creating images which uses intentionally limited ranges of radiation in the ultraviolet, visible or infrared portions of the spectrum.
It has uses in artistic and scientific photography.
<BR><P>
Early day photographers often needed to work around the inherent spectral sensitivity limitations of the photographic materials available to them.
Their photographic materials were sensitive primarily to blue light.
Rich blue skies photographed much too light while vegetation and skin photographed too dark.
Look closely at the actors and actresses in early motion pictures.
Often the white powder makeup they used did not get applied too close to their eyes and the result can be quite comical in close-ups.
Fortunately, current photographic materials extend well past the approximately 500 nanometer upper limit of early day imaging.
<BR><P>
Modern photographic materials are available with sensitive to a wide portion of the spectrum, ranging from 250 nanometers (ultraviolet) to 925 nanometers (infrared).
There are many applications for the selective use of this spectrum.
Specific characteristics of a subject can be emphasized or selected out by limiting the range of spectrum used to create an image.
Colored filters are the primary tool for selective use of spectrum with conventional photography.
Digital image editors open up some new possibilities for the creative use of spectral selectivity.
<BR><P>
The topics linked below provide an introduction to spectral selectivity, some technical information for making use of it and a few typical applications.
</TD></TR></TABLE>
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<BR><P>
<TABLE BORDER=0 CELLPADDING=1 CELLSPACING=1 WIDTH="600">
<CENTER><A NAME="01"><H2>Contents</H2></A></CENTER>
<TR><TD><HR></TD></TR>
<TD>
<H3>Color Vision </H3>
<UL>
<LI><A HREF="vis00010.htm">Color Vision </A>
<SMALL> - Human perception of different wavelengths of light</SMALL>
<LI><A HREF="vis00020.htm">Color Space </A>
<SMALL> - The color space defined by three color sensors</SMALL>
</UL>
<H3>Reproduction of Color</H3>
<UL>
<LI><A HREF="rep00010.htm">Tri-Color Photography </A>
<SMALL> - Spectral response of tri-color filters</SMALL>
<LI><A HREF="rep00020.htm">Color CRTs </A>
<SMALL> - Spectral response of Cathode Ray Tubes</SMALL>
<LI><A HREF="rep00030.htm">Color Slide Film</A>
<SMALL> - Spectral sensitivity of Kodachrome 25</SMALL>
<LI><A HREF="rep00040.htm">Web Browser Color</A>
<SMALL> - Down coloring an RGB image to 8-bit video</SMALL>
</UL>
<H3>Photographic Spectral Sensitivity</H3>
<UL>
<LI><A HREF="pss00010.htm">B&W Films </A>
<SMALL> - Spectral sensitivity range of B&W photographic materials</SMALL>
<LI><A HREF="pss00020.htm">Exposure Meter </A>
<SMALL> - Spectral sensitivity range of exposure meters</SMALL>
<LI><A HREF="pss00030.htm">Panchromatic Film Ad </A>
<SMALL> - Photos from an early ad for panchromatic film</SMALL>
</UL>
<H3>Filtering Spectrum</H3>
<UL>
<LI><A HREF="cf000010.htm">Color Filter Absorbtion </A>
<SMALL> - Absorbtion curves for some typical color filters</SMALL>
<LI><A HREF="cf000020.htm">Filter Factors </A>
<SMALL> - Exposure adjustment for B&W photography</SMALL>
<LI><A HREF="cf000030.htm">Light Source Color Temperatures </A>
<SMALL> - Color temperatures for some common light sources</SMALL>
</UL>
<H3>Masking Spectrum</H3>
<UL>
<LI><A HREF="ms000010.htm">Combining Images </A>
<SMALL> - Masking off a range of spectrum by combining images</SMALL>
<LI><A HREF="ms000020.htm">Raster Ops </A>
<SMALL> - Useful Adobe Photoshop raster ops for masking spectrum</SMALL>
<LI><A HREF="ms000030.htm">A Notation For Spectral Selectivity</A>
<SMALL> - A tool to plan and record complex operations</SMALL>
<LI><A HREF="ms000040.htm">A Spectral Selectivity Metric</A>
<SMALL> - The digital image as a spectral selectivity data set</SMALL>
<LI><A HREF="ms000050.htm">Image Color and Tone Mapping</A>
<SMALL> - Altering images in an imaging editor.</SMALL>
</UL>
<H3>Infrared Photography</H3>
<UL>
<LI><A HREF="ir000010.htm">Infrared Characteristics </A>
<SMALL> - Infrared conditions and recommendations</SMALL>
<LI><A HREF="ir000020.htm">B&W Infrared </A>
<SMALL> - Spectral sensitivity of Kodak HS Infrared film</SMALL>
<LI><A HREF="ir000030.htm">Color Infrared </A>
<SMALL> - Spectral sensitivity of Kodak Color Infrared film</SMALL>
<LI><A HREF="ir000040.htm">Infrared Exposure </A>
<SMALL> - Determining exposure for infrared film</SMALL>
</UL>
<H3>Ultraviolet Photography</H3>
<UL>
<LI><A HREF="uv000010.htm">Ultraviolet</A>
<SMALL>Characteristics and techniques of ultraviolet photography</SMALL>
<LI><A HREF="uv000020.htm">Ultraviolet Photographic Materials</A>
<SMALL>Spectral sensitivity plots for UV films and filters</SMALL>
</UL>
<H3>Applications</H3>
<UL>
<LI><A HREF="ap000010.htm">Camouflage Detection </A>
<SMALL> - A WW-II Kodak ad for infrared film</SMALL>
<LI><A HREF="ap000020.htm">Forest Vitality </A>
<SMALL> - Measuring the health of conifers with infrared</SMALL>
</UL>
<H3>Links</H3>
<UL>
<LI><A HREF="http://www.mat.uc.pt/~rps/photos/FAQ_IR.html">Infrared FAQ </A>
<SMALL> - Some useful information on infrared photography</SMALL>
<LI><A HREF="http://www.math.liu.se/%7Ebehal/photo/rit.edu/ARTICLE_IR_UV.txt">IR & UV Photo Info </A>
<SMALL> - A page of technical information on UV and IR photography</SMALL>
<LI><A HREF="http://ruly70.medfac.leidenuniv.nl/~cor/ir-gallery.html">Infrared Gallery </A>
<SMALL> - An infrared photo gallery with some nice IR images</SMALL>
<LI><A HREF="http://www.demon.co.uk/atsf/ilight/">Invisible Light </A>
<SMALL> - A nice infrared photography site with a many links</SMALL>
<LI><A HREF="http://www.the-shak.demon.co.uk/gallery.htm">The Ghostly Gallery </A>
<SMALL> - A nice collection of B&W infrared photos </SMALL>
<LI><A HREF="http://www.netlink.co.uk/users/spear/inred.html">Color Infrared </A>
<SMALL> - A small collection of color infrared photos with filter examples</SMALL>
<LI><A HREF="http://members.aol.com/Waermebild/index.html">Beyond Photographic Infrared </A>
<SMALL>Georg Dittie's Thermal Infrared & Thermography site</SMALL>
<LI><A HREF="http://asp1.sbs.ohio-state.edu/satimages.html">Satellite Imagery </A>
<SMALL> - A collection of interesting satellite images</SMALL>
<LI><A HREF="http://www.kodak.com/productInfo/aerialSystems/TI0274_contents.shtml">Kodak Aero Infrared </A>
<SMALL> - Kodak pages on Aero Infrared film for aerial photography</SMALL>
<LI><A HREF="http://www.kodak.com/productInfo/catalog/genInfo/dcsIRDigitalCameras.shtml">Digital Infrared Cameras </A>
<SMALL> - Product information on Kodak digital infrared cameras</SMALL>
<LI><A HREF="http://www.bhphotovideo.com/photo/navigation.html">B&H Photo </A>
<SMALL> - Mail order photo dealer that stocks infrared films and filters</SMALL>
<LI><A HREF="http://www.freestylesalesco.com/">Freestyle </A>
<SMALL> - Mail order photo dealer that stocks some infrared films and filters</SMALL>
</UL>
</TD>
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<ADDRESS>
<H5>C1997 by Ed Scott -
<A HREF="mailto:dotted.dog@xxxxxxxxxxxxxxxx"><dotted.dog@xxxxxxxxxxxxxxxx></A><BR>
and Hollis Bewley -
<A HREF="mailto:hbewley@xxxxxxx"><hbewley@xxxxxxx></A></H5>
</ADDRESS>
<H4>Return to <A HREF="http://www.photo.net/photo/">photo.net</A></H4>
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