Getting Started

Visualizing your data!

If you have not already, please see see the installation guide for details on how to install NTV

NTV was written to be an extendable application for visualizing data. Although originally intended for visualizing astronomical data sets, NTV is flexible enough to handle visualizing almost any two or three dimensional data-set. Additionally the robust plug-in system allows for easily extending NTV to suit individual needs. What follows is a quick primer for getting up to speed so you can quickly dive into data.

##Loading Data NTV can accept data in a few different ways:

• File > Open will allow selection of a fits file to be loaded, fits file may be either a two or three dimensional array. If additional files are needed please use File > Add Image which will extend a two dimensional array into a three dimensional array with the new image appended in the z-direction. If the image is already a three dimensional array, it will be extended with the new data.

• Drag-And-Drop is supported for loading in a file from a file browser. Currently this only supports loading in one file, if multiple files are needed, use File > Add Image. This limitation will be changed in future versions

• Sending array from outside application. NTV is designed to be interacted with from other programs, for more information please see Embedding NTV. If you are using the included python embedding code, use the showArray(numpy_array) method after creating and NTV object to send a list or array to NTV.

##Adjusting the Image

NTV attempts to show an ideal image directly after loading, but some visualizations may require tweaking the image, the following tools are available to allow robust manipulation.

###Brightness and Contrast Upon loading an image NTV will attempt to identify the best brightness and contrast for the image. Certain feature of the image may dictate changing this. The color bar located to the left of the image not only displays the current values, but also allows changing the value. Left clicking and or dragging will change the grey point of the image, the value which is mapped to grey. Right clicking and or dragging away from the grey point will change the contrast of the image, that is to say how far away values from the value which corresponds to grey will be mapped to black and white. This sounds confusing but a high contrast image will have the values of the image which correspond to black and white points close to each other, with grey in the middle, and low contrast images the values will be spread far apart. An additional more visual way of manipulating brightness and contrast can be found in the levels plugin, for more details please see usage

###Panning and Zooming Sometimes only a region of an image will be of interest, for these cases NTV includes a tool bar underneath the image for manipulation. Here you can find tools for panning, zooming, and stepping through the history of views. Those familiar with the tool bar provided by matplotlib will feel right at home.

###Scaling Scaling allows differentiating values based on various criteria. Currently we support linear scaling, ie the values the image contains, and log scaling, the values are mapped through a logarithm.