User manual

histogram will evolve dynamically respectively to the current image. All adjusting

possibilities of the pixel dynamics are the same as for a single image. In the case of large

data cubes (several hundreds of megabytes), modifying operations of the initial

threshold can take several seconds before the results gets displayed on all the images of

the cube.

Contrast tuning in the view

Aladin has a contour extraction tool that

lets you generate isophotes for and image.

The “Overlay => Contour plot …” opens a

control window that will let you adjust the

number of isophotes needed as well as their

pixel level with respect to the histogram of

the pixel distribution in the image. It is

possible to smooth or to reduce the noise in

the image before the extraction of contours.

You can also restrain the extraction to the

part of the image that is seen in the view.

This last parameter is useful to reduce the

computing time for very large images.

Contours will be saved in a plane of the

stack, and overlaid to the initial image, but

also to other images (celestial coordinates

are saved). For example, this property lets

you compare easily two images at different

wavelength.