*@Tim Holy*: Many thanks for the reference, I completely missed ImageCmap. I'll give it a try.
*@Steven G. Johnson*: Yes, in my everyday work I am actually using my Healpix.jl library together with PyPlot. However, I am looking for a solution which does not require potential Healpix.jl users to install Python. (Part of my colleagues just use IDL under Windows, convincing them to install Julia would already be a tough effort!) Maurizio. On Thursday, August 13, 2015 at 4:38:58 PM UTC+2, Maurizio Tomasi wrote: > > Hi to everybody, > > I am the creator of Healpix.jl, a Julia package ( > https://github.com/ziotom78/Healpix.jl) which implements algorithms > related to the Healpix sphere tessellation scheme ( > http://healpix.jpl.nasa.gov/). The Healpix scheme subdivides a sphere in > patches (pixels) of equal area, and it is widely used in cosmology. I am > writing to julia-user because I would like to implement visualization > functions too, but I haven't figured out what is the best way to implement > them. > > So far, I have used the Healpy (https://github.com/healpy/healpy) library > as a reference for my implementation. Healpy wraps the original C++ Healpix > library in a Python module. It uses Matplotlib to create plots of spherical > projections. Internally, both the original C++ Healpix library and Healpy > produce such plots by calculating a bitmapped representation of the > projection: they convert each (x,y) point in the image plane into a > normalized (u,v) coordinate, which is then spherically projected to a point > on the sphere's surface. The value associated to the point on the sphere > determines the color of the point at (x,y). Here are a few examples of > typical Healpix maps: > http://healpix.jpl.nasa.gov/images/skymaps/ecl53s.gif (Mollweide > projection), http://healpix.sourceforge.net/html/plot_orthpolrot.png > (Orthogonal projection). > > The algorithm is really easy to implement in Julia, but I cannot decide > how to actually do the following: > > 1. How to interactively show the map by e.g. opening a window, or by > displaying the image directly in a IJulia notebook? > 2. The bitmap produced using this algorithm associates a scalar to each > pixel, but one usually wants to convert such scalar through a color map in > order to have a RGB value to be actually drawable. (I am interested in > piecewise-linear maps). > 3. When displaying the map, how to put a color bar under the map, like in > the two links I provided above? > > I have had a look at ImageView, and it look ok for point 1. However, it > seems to me that it is oriented towards "real" image files, because I > cannot find support for color maps and color bars. If it is really so, is > there any other Julia package which would be relevant for my purposes? > > Thanks a lot, > Maurizio. >
