Go ahead and submit the bug report. Also let me know what ImageView does with it. (I never use colormap images myself, so this is less well-tested.)
A pull-request fixing the problem would be even better, of course! --Tim On Friday, August 14, 2015 06:54:19 AM Maurizio Tomasi wrote: > Tim, does ImageCmap works with latest Julia? I cloned the latest Julia > repository (0.4), added the Color, Images, and ImageView package and run > this code (adapted from > https://groups.google.com/forum/#!searchin/julia-users/%22ImageCmap%22/julia > -users/T-i1JdwB4zk/f7FEsh4En4oJ but using PBM format in order not to rely on > ImageMagick) with no avail. > > using Images, Color > > # build a sample image > datafloat = reshape(linspace(0.5, 1.5, 60000), 200, 300) > # convert the raw 0.5:1.5 data to a integer type, so we can index > dataint = iround(Uint8, 254*(datafloat - 0.5) + 1) # ranges from 1 to 255 > # build our colormap > b = RGB(0,0,1) > w = RGB(1,1,1) > r = RGB(1,0,0) > cmaprgb = Array(RGB, 255) > f = linspace(0,1,128) > cmaprgb[1:128] = [(1-x)*b + x*w for x in f] > cmaprgb[129:end] = [(1-x)*w + x*r for x in f[2:end]] > > img = ImageCmap(dataint, cmaprgb) > > imwrite(img,"image.pbm") > > The error is the following: > > ERROR: MethodError: `mapinfo` has no method matching > mapinfo(::Type{Images.ImageMagick}, > > ::Images.ImageCmap{Color.RGB{T<:Union{AbstractFloat,FixedPointNumbers.FixedP > ::oint}},2,Array{UInt8,2}}) > Closest candidates are: > mapinfo(::Type{Color.RGB{FixedPointNumbers.UfixedBase{UInt8,8}}}, ::Any) > > mapinfo(::Type{Color.AlphaColorValue{Color.RGB{FixedPointNumbers.UfixedBase{ > UInt8,8}},FixedPointNumbers.UfixedBase{UInt8,8}}}, > ::Any) > > mapinfo{CT<:Union{Color.AbstractAlphaColorValue{C<:Color.ColorValue{T},T<:Re > al},Color.ColorValue{T}}}(::Type{Color.RGB24}, > ::AbstractArray{CT<:Union{Color.AbstractAlphaColorValue{C<:Color.ColorValue{ > ::T},T<:Real},Color.ColorValue{T}},N}) > ... > in imwrite at /home/tomasi/.julia/v0.4/Images/src/io.jl:585 > in anonymous at /home/tomasi/.julia/v0.4/Images/src/io.jl:576 > in open at iostream.jl:114 > in imwrite at /home/tomasi/.julia/v0.4/Images/src/io.jl:573 > in imwrite at /home/tomasi/.julia/v0.4/Images/src/io.jl:186 > > Before submitting any bug report, I would like to be sure I'm not getting > something totally wrong. > Maurizio. > > On Thursday, August 13, 2015 at 6:36:44 PM UTC+2, Tim Holy wrote: > > Images (on which ImageView is based) has an ImageCmap (= "image colormap") > > type. You could play with it and see how far you get. > > > > Also, see the "MapInfo" section of > > http://timholy.github.io/Images.jl/function_reference.html. It's a crazy- > > powerful mechanism for on-the-fly changes in how data are mapped to screen > > pixels. > > > > --Tim > > > > On Thursday, August 13, 2015 05:44:16 AM 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.
