How do I remove the seams between instruments?
How do I create a custom filter?
How do I make a movie with FESTIVAL?
Each image (EUVI, COR1, COR2, etc.) is scaled independently by FESTIVAL before it is displayed. The minimum and maximum values taken into account are defined in the enhancement GUI. This maximizes the visibility of features in each instrument, but it is sometimes nice to be able to create a seamless composite image of the corona. This can be done by manually adjusting the minimum and maximum values in the enhancement GUI.
FESTIVAL has a set of predefined filters that can be applied to the images, but you can easily build your own filter. A FESTIVAL filter is an IDL expression or function that accepts a matrix as input, applies a transformation, and outputs the result in another matrix. FESTIVAL filters can therefore be built-in IDL functions, but they can also be user written. The filter is specified in the filter dialog box as a command line. As shown below, the input matrix must always be called image.
A filter based on an IDL built-in function could be smooth(image, 3, /edge) for a simple smoothing filter...
A filter based on a user written function could be myfunct(image, box), with myfunc written by the user
function myfunc, image, box
if n_params() eq 1 then box = 5
return, image - smooth(image, box, /edge)
end
The size and position (latitude and longitude) of the filtered image on the sky are never modified by a filter. The filtered image is put at the same location as the original, even though input and output matrices do not have to be of the same size.
FESTIVAL is able to save at once a whole sequence of images. FESTIVAL is also able to encode the sequence in a movie (e.g. an avi or mpeg file) if you have mencoder installed on your machine. mencoder is multiplatform a state of the art movie encoder that produces much better movies than the IDL built-in encoder. You can naturally use your favorite video editing software to encode the individual frames into a movie or an animated GIF. Under Windows, the Windows Movie Maker is an easy way to make movies, even if the encoding options are limited. Photoshop is a possibility if you want to create an animated GIF. FESTIVAL comes with default encoding options. These can be changed in the save sequence dialog but you can naturally call mencoder manually for more advanced manipulations, like double pass encoding. The following command line
mencoder "mf://*.jpg" -o mymovie.avi -ovc lavc -lavcopts codec:msmpeg4v2:vbitrate=3600
converts all jpg images in the current directory into an avi mpeg4 movie. Tip: To avoid the flicker from frame to frame, turn off the autoscale in the visualization enhancement GUI and set the limits to values that work well for the whole sequence.