📄 imgspectrumexpo.htm
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<!-- This file create by Bob L. Sturm Sept 02 2003, using vi. Originally inspired by the MATLAB Auditory Demonstrations package created by Univ. of Sheffield, UK.--><HTML><HEAD> <TITLE>SSUM: Image Spectrum Explorer</TITLE> <link href="style.css" rel="stylesheet" type="text/css"></HEAD><BODY><table cellpadding=0 cellspacing=0 align=center border=0 width="100%"><tr> <td> <IMG SRC="imgspectrumexpo_t.jpg" WIDTH=137 HEIGHT=146> </td> <td align=center> <H1>Image Spectrum Explorer</H1> </td></tr><tr> <td colspan=2 align=center bgcolor=black> <H6><A HREF="#introduction">Introduction</A> <A HREF="#demonstration">Demo</A> <A HREF="#investigate">Investigate</A> <A HREF="#reading">Reading</A> <A HREF="#credits">Credits</A> <A HREF="SSUM.htm">Home</A></H6> </td></tr></table><br><A NAME="introduction"></A><H2>Introduction</H2><P>The spectral information of an image, or its spatial frequencies, can be exploredin this application.</p><br><A NAME="demonstration"></A><H2>The tool</H2><P>This demonstration has two windows: one to display the image, and the other topresent spectral and pixel information about the image. The larger colorfulplot on the left is the two-dimensional Fourier transform of the entire image. Thetwo plots below this show the spectra in the horizontal and vertical directionsfrom the cross-hairs on the image in the window on the right. One can chooseto either display the spectrum or the pixel values at the position of thecross-hairs.</p><CENTER><a href="imgspectrumexpo.jpg"><IMG SRC="imgspectrumexpo.jpg" width=770 height=740></a></CENTER><br><p>The two-dimensional Fourier transform is a difficult thing to describe. The centerof the plot represents the lowest frequency possible. As one moves further from thecenter, the frequency increases. The angular position of a component roughly corresponds to the angular spectral component in the image. In this particular imagethere is a lot of energy in the angles shown in the two-dimensional Fouriertransform. The tilt of the cameraman's body and tripod create these frequencies.</p><br><A NAME="investigate"></A><H2>Things to investigate</H2> <OL> <LI>Load "cameraman.gif." What happens to the horizontal spatial frequencieswhen the cross-hairs meet the top of the man's head? <LI>Compare the two-dimensional Fourier transform of the images: "stripes.jpg,"and "circles.jpg."</OL><A NAME="reading"></A><H2>Further reading</H2><br><A NAME="credits"></a><H2>Credits</H2><p></p><hr noshade><P class="credits">Produced by Bob L. Sturm and Dr. Jerry Gibson.<br>Release date: February 2, 2004<br>Copyright 2003 University of California, Santa Barbara</p></BODY></HTML>⌨️ 快捷键说明
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