Change specific colours in pcolour

Hi, i'm trying to change the background of my graphs so that NaN values come up as black.

I have tried putting the following commands in various places through out the plot program such as:

whitebg([0 0 0])

set(gca, 'Color', 'Black')

but nothing seems to work. I also need to change the colour of the 0 values to white. here is the plotting part of the program

figure('Visible','off')   % observation u 
    plot1=pcolor(times, heights, obsArrayU);       
    set(plot1,'edgecolor','none');
    title(['Observation of u for station: ' radarStr ' from ' ...
            sDayStr '-' sMonthStr '-' sYearStr ' to ' eDayStr '-' eMonthStr '-' eYearStr ...
            ' for ' model ' model'], 'FontWeight','bold')
    set(gca, 'Clim', [-50, 50]);      colorbar;       
    colormap(jet(20));                xlabel(['Time ' timeLabelName]);    
    ylabel('Height (km)');            set(gca, 'XTick', xTickPoints);  
    set(gca, 'XTickLabel', date);     %xticklabel_rotate;     
    n=get(gca,'YTick');
    set(gca,'yticklabel',sprintf('%.1f |',n/1000'));        
    print('-djpeg', ...
         ['Images/obs__u_radar_' radarStr  '_' model '_frm_' sYearStr sMonthStr sDayStr...
         '_to_' eYearStr eMonthStr eDayStr])

here is a link to the outcome: https://www.dropbox.com/s/0rzlcrxl6ex3h4g/obs__u_radar_03019_ukv_frm_20110101_to_20110107.jpg

any help would be appreciated, thank you

Answer 1

[Image Analyst]

You need to modify your colormap. What color are nan's coming up as now? You're setting CLim to [-50, 50] so what element of jet(20) shows up as 0? jet(1) is -50, and jet(20) is 50, so is 0 then jet(10) or jet(11)?

myColorMap = jet(20);
% Set 0 to white.
myColorMap(10,:) = [1 1 1];
colormap(myColorMap);

But why are you using pcolor in the first place? Why not use image() or imshow()? Why do you want to lose a row and a column of your data by using pcolor()? Did you not know that? Then just run this to prove it to yourself: pcolor(rand(4,4)).

Answer 2

[Jason Baxter]

ah i figured it out, the background wasn't changing because figure('visible', 'off' was stopping it for some reason.

I will try using image or imshow now, i've never used them before, I was aware that I was losing column but didn't know how to fix it thanks again