ATV: Notes on the 2.0 beta release.

The 2.0 beta version of ATV was released in 2007.  There are a lot of new features here, and because the program has grown fairly complex, it may contain bugs.  But it's generally pretty stable and works well, and should be ready for everyday use.

If you're using ATV 2.0, make sure you have the most recently updated version of the IDL Astronomy User's Library.   There are a couple of library routines used by ATV that have been modified in 2007.

The major new things in ATV 2.0 include:

• Asinh scaling.  This idea comes from Robert Lupton's SDSS work (take a look here), and it's really excellent- I think this is the best new feature in ATV.  It works so well that I've made it the default scaling mode.  If you work with images having a very high dynamic range (things like quasar host galaxies or debris disks around bright stars), looking at your images with asinh scaling can be a revelation. 
  
• Along with the asinh stretch, the autoscaling behavior has been changed.  Now, ATV measures the sky mode and sky sigma for each image and determines the minimum autoscale value from these parameters.   This is much better than how ATV used to do its autoscaling, and the result is that for most normal kinds of images, it will automatically display the image in a way that looks pretty good.
  
• Now, the autoscaling parameters are different in asinh, log, linear, and histeq modes.
  
• A new lineplot window with interactive user control over plot ranges, and postscript output
• A new vector plot mode to plot pixel values along an arbitrary line through the image
• A new rotate/zoom menu
• New overplot options, including region overplots (circles, ellipses, boxes, lines)
• A pixel table widget that shows pixel values around the cursor position
• Easy downloads of DSS and FIRST images.
• More keyboard shortcuts, for SetBlink (Shift-1, Shift-2, Shift-3) and changing mouse mode (m)
  
• A new "atv_activate" command that's useful when you need to display a sequence of images from another IDL program, and useful for debugging
• The ability to use ATV with the IDL virtual machine: in other words, you can run ATV without an IDL license.  I hope this will be useful to some people. 
  
• A simple way to make RGB composite images.
  

See the instructions page for details on how all of this works.  Most of it should be pretty easy to figure out- just give it a try.  

 
I'm continuing to add new features when I have time to work on this.  Right now the to-do list includes better photometry options, the ability to load image stacks, and a bunch of other stuff.
 

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