Kview App

[Crystle Rike]

Ihave a PNG file created using libPNG library. The file opens perfectly on Windows picture viewer and MS Paint, but opening with kview (on Linux RHEL5) or QuickTime PictureViewer (on Windows) fails - the former reports a "libpng read error whereas the latter reports the file as being corrupted. A similar problem is seen when trying to process the PNG using ImageMagick library on Linux. Given that the PNG opens fine on some applications, it doesn't seem that the file is really corrupted; I therefore suspect some problem with version compatibility, but I am not sure. I tried searching the web but couldn't find any information on the root cause or a solution to this problem. Can someone please guide me on this?

Judging from the example image you posted in the comments, the problem is that your PNG lacks the ending IEND chunk -something you can test by opening it with tweakpng and inspecting the structure visually, or choosing "Check Validity-F5". It is somewhat predictable that those kind of PNG are displayed by some viewers and rejected by others.

kview and kubes: displaying two data cubesThe kview and kubes programmes can be used to lookat two cubes at the same time. They do not volume render the data,but display the data cube along the three principle planes (typicallyand ). The programmes know about two data sets, one is calledSet 1, the other Set 2. The two datasets may becombined in various ways, and allow you to step through the cubes andcompare the two data sets. One can also loop over a certain range ofchannels or position-velocity diagrams.The original idea behind kubes was to compare a data cubewith a model cube and it is used for this in the modeling software,but of course kview and kubes can be used for anyone or two data sets. The data sets do not have to be cubes even,they can also be single images, or one can be a cube and the other asingle frame. One application of this kind is to overlay the contoursof the channels of an HI data cube over an optical image from thedigital sky survey. If you are using kubes, youwill need to use skyve in aips to regrid to aproper coordinate system) or use skyview to download theimage. If you use kview you don't have to worry aboutregridding.Another application of kubes is that one usesxray to make a movie of a data cube and one of a modelcube, and use kubes to look at the rendered cubessimultaneously (side by side), provided these are not made with theHot Gas Substances or the Hot Gas Continuousshader. This can be very instructive.

kview startupkview should be started with:kviewSee the Karma User Manual section on kview.You don't have to worry about available colours on the screen: ifthere are insufficient colours (perhaps because you have a WWW browseror some other visualisation tools running), kview (and therest of the standard visualisation tools) will automatically create anew colourmap. On most hardware this will mean that you will getcolour flashing when you move from one window the another.

Image SequencesSee the Karma User Manual section on movies.kubes enables you to make movies similar to eg. tvmovie in aips, i.e. a sequence of images played intime. Under the button Loop sits a window that gives thiscontrol. (see the section on sequences). An alternative to step through manually through a sequence is to havethe mouse in the display window and to click with the middle button togo to the previous frame and with the right button to go to the nextframe. This also works when you have set the display modeto blink.Sequences are also possible if you have overlayed eg. the contours ofof a data cube over an 2D image. Stepping through the sequence willchange the image of which the contours are shown.

Extra Colourtableskubes has the same colourtablecontrol as all the other visualisation software. The only differenceis that there are a few extra colourtables compared tokview or xray. There are two tables for theImages combined mode: Two images 1 andTwo images 2. Both are red and green, the difference beingthat the colours are swapped with respect to each other. There is also a colourtable colled Ron&Renzo. Thiscolourtable has 9 distinct colours. The boundary between te blue andthe green colour stays fixed at the zero level in themap.

kview extraskview has the following features over kubes:Axis labelling in the profile window.Co-ordinate grid in axis labelling, and support for mostrotations of the co-ordinate system.Support for native DSS (digital sky survey) co-ordinatesystem, without the need to regrid. Also supports more projectiontypes (CAR, ARC and ZEA).Much faster display of contours.Ability to choose the direction of the profile axis (i.e. notlimited to Z).Interactive controls to set the displayed intensity range (cliplevels).Logarithmic and square-root intensity transfer functions. Thisis especially useful for optical and radio maser data.Ability to export whole dataset or visible subset, in a varietyof formats.Magnifier window.Ability to display 24 bit (TrueColour) images/movies on a 24 bitdisplay. This includes independent colourmap control for the red,green and blue channels.Ability to interactively select and compute boxed profiles,including being able to compute the total flux rather than flux perbeam.Interactive fitting of gaussians to linear and circularprofiles.Overlay of beam.Decimation and subcubing of large datasets to reduce memoryrequirements.Loading of files specifying annotations to be overlayed.Interactive annotation editor.Interactive, graphical setting of image intensity clip limits.

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