Readme PTViewer 3.1 For a description of basic PTViewer features please see the documentation for PTViewer 2.5 at . This document describes new additions in versions > 2.5. (1) Display of high dynamic range images (HDR). PTViewer reads two formats: A lossless format developed by Ward for the Radiance system (see http://radsite.lbl.gov/radiance/) and a highly compressed version of this format suitable for low bandwidths (fjpeg, see documentation at ). Radiance files are recognized by the extension ".img", ".pic" or ".hdr" while fjpeg-files should be named with extension ".fjpg". These filetypes can be used as equirectangular source for panoramic images, and as rectilinear source in ptzoom (i.e. also for cubic panoramas). (2) HDR-images can be used together with the following three new applet parameters: name: exposure type: floating point numeric constant default: 1 description: This value sets the initial factor for brightness adjustment. Example: displays the image 2x brighter than the stored pixel values. name: gamma type: floating point numeric constant default: 1 description: This value sets the gamma factor for brightness adjustment. Since the floating point formats typically store linear luminance data, a gamma transformation may be used to compress dynamic range.Example: name: autorange type: floating point numeric constant, range 0-100 default: 100 description: This value is used for the automatic brightness adjustment loop. autorange=0 fixes the average pixel value within the center region of the viewer window (width/2 X height/2) to the value encountered in the initial view, i.e. the viewer exactly delivers the same average brightness. autorange=100 turns autoadjustment off. Values between 0 and 100 partially correct brightness. Example: (3) The viewer window may be sharpened using a highboost filter (a modified unsharp mask). Sharpening is useful for zoomed-in views which usually become quite soft. Therefor, this feature is set by a zoom-dependend parameter. It is available for all types of images (low and high dynamic range). name: fovsharp type: floating point numeric constant, range 0-180 default: 0 description: The viewer window is sharpened when horizontal view becomes smaller than fovsharp. (4) Compatibility issues. PTViewer 3.1 is designed to replace existing previous versions of PTViewer and provide all previous features, i.e. it should work with low dynamic range images equally well. Additionally, some math routines have been optimized and debugged, and some minor errors been corrected. One bug which caused PTViewer to stutter under certain viewing conditions has been removed. However, not all extensions have been thoroughly tested with the new version, and it is advisable to first test the new version before replacing it in working installations. PTViewer 3.1 no longer runs as single class file as did PTViewer 2.5. You can still downsize PTViewer by removing unneeded extensions from the jar file, but you have to provide at least the class files ptviewer.class and the new class file ImageData.class. Only very outdated browsers have problems with jar files so this should be no limitation. Copyright C 2004 H. Dersch