Re: An IDL cron job, true color plots, Xvfb, Z-buffer, and all sorts of troubles

Kathryn,

below is the scheme that I use. The trick is to map the z uffer plot to
true 
colors. Also, I make a huge plot in the z-buffer and then rebin the plot
to 
a smaller size so my fonts looks decent.

Good  luck, haje



; create spectrogram in z buffer and take snapshot

thisdevice=!d.name

set_plot,'z'

device,set_resolution=[2400,3200],set_font='helvetica',/tt_font,set_character_size=[40,50]



*** plot here what needs to be plotted ***



; take snapshot of z buffer

snapshot=tvrd()

device,/close

set_plot,thisdevice


; convert snapshot from index colors to true colors

tvlct,r,g,b,/get

sz=size(snapshot,/dimensions)

snapshot3=bytarr(3,sz[0],sz[1])

snapshot3[0,*,*]=r[snapshot]

snapshot3[1,*,*]=g[snapshot]

snapshot3[2,*,*]=b[snapshot]


; shrink snapshot

xsize=600

ysize=800

snapshot3=rebin(snapshot3,3,xsize,ysize)


; write jpeg graphics file

jpg_fname=file_basename(fname,'dat')+'jpg'

write_jpeg,jpg_fname,snapshot3,/true,quality=100


<kathryn.ksm@[EMAIL PROTECTED]
> wrote in message 
news:72597909-3fc0-4419-be49-578f37fea7c1@[EMAIL PROTECTED]
> Hi folks,
>
> This newsgroup has been a huge help to me with these sorts of problems
> in the past, and I am hoping once again to draw on your expertise.
>
> My problem is a little complicated.  I have a particular plotting
> routine that uses a color scale to represent signal response over a
> grid of detectors.  I use this a lot and it's really handy.  It also
> took me a really long time to get it to work and to be able to
> write_png files from it without getting goofy colors.  What I would
> like to do is automate this routine and run it with a cron job,
> outputting png files to include in a daily web page.
>
> I have noticed that quite a few people have tried to do similar things
> and run into problems.  I have problems with all of the suggested
> solutions.  Any one of them would be fine but I can't get them to
> work.  So here goes:
>
> option 1) use the Z buffer:  Here I think I am running into problems
> with my understanding of true-color display issues in IDL.  My plot
> routine includes a line  'Device, decomposed = 0' and the Z-buffer
> doesn't work the same way as the X buffer.  That's problem number
> one.  Problem number two is that I can't figure out how to take the Z-
> buffer plot and make a png file out of it with correct colors.
>
> option 2) write to a ps file and convert it to png after the fact.  I
> have similar problems here with my Device, decomposed = 0, and I don't
> understand how to translate my plotting routine so that it will do the
> same thing with the ps device that it does with standard X output.
>
> option 3) use the /pixmap option with an X window, and then use Xvfb
> to run a virtual X session so that I can run this from cron.  I have
> Xvfb installed and with some fiddling, I can get the authentication to
> work out so that I don't get an immediate Xlib: connection to ":1.0"
> refused by server, but even then I still get WINDOW: Unable to connect
> to X Windows display: :1.0 errors, even though the DISPLAY variable
> looks to be set correctly to me.   I really hoped I could get this to
> work, because doing window, 1, /pixmap, running the plotter, and then
> calling write_png, 'file.png', tvrd(/true) works wonderfully and gives
> exactly what I want... just not through cron.
>
> I think the main reason I'm having so much trouble here is I'm trying
> to get something to work with color tables and true-color display
> without really understanding them.  A stripped-down version of the
> plotting routine is below.  I would invoke it with something like
>>plot_test, [0,2,3],[0.2,0.7,1.0].  Before I run this, I have quite a
> few graphics setup calls in my idl_startup file.  Between running it,
> I typically do
> loadct, 0
> !p.color = !black
> !p.background = !white
> to make the display look right each time.
>
> Sorry for the long-winded question.  Sample plotting routine follows:
>
> pro plot_test, indices, color_scale,$
>                title=title
>
> if n_elements(title) eq 0 then title=''
>
> ; example simple grid of 4 points:
> x_pos=[1., 2., 1., 2.]
> y_pos=[1.,1.,2.,2]
>
> ;plot, the center points for each detector:
> plot, x_pos, y_pos,  xrange=[0,3],yrange=[0,3],/xstyle,/ystyle,/iso,$
>  psym = 3, title = title
> Device, decomposed = 0
> LoadCT, 33
> ; determine the color scale to use
> color_scale=float(color_scale)
>
> color_values = ((color_scale - min(color_scale))/(max(color_scale)-
> min(color_scale)))* 255
>
> ;plot circles filled with the colors in the scale
> for i=0,n_elements(indices)-1 do begin
>    polyfill, circle(x_pos[indices[i]],y_pos[indices[i]],0.25),
> color=color_values[i]
> endfor
>
> colorbar, /vertical, format='(F6.2)',$
>          range=[min(color_scale),max(color_scale)]
>
> end
>
>
> - Kathryn
>