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Earth Observing System Data Visualization

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Earth Observing System Data Visualization

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28 Oct 2002 (Updated )

Read Earth Observing System (EOS) data products in HDF format and visualize them in MATLAB(R).

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colorscale(varargin)
function varargout = colorscale(varargin)
%COLORSCALE Add a color scale bar using part of the figure's colormap.
%   COLORSCALE creates a color scale for use with an integer-valued image
%   which has been encoded and quantized via a monotonic transformation
%   from a real-valued array.  The original array has physically meaningful
%   units, but the image does not.  The transformed image has been displayed
%   with a direct mapping to the figure's colormap. (That is, the IMAGE object
%   has a CDATAMAPPING of 'direct'.)  The image and/or color scale may not
%   use the entire colormap.  The colormap may contain special values for
%   null data areas, and these special values may be excluded from the
%   scale bar.  Or, the colormap may be deliberately partitioned and shared
%   with a different image in the same figure, and that image may have its
%   own entirely distinct color scale.  In these cases, unlike the COLORBAR
%   function in MATLAB, COLORSCALE can limit the displayed colors to the
%   appropriate interval within the figure's colormap.
%
%   H = COLORSCALE(CMAPLIM,DATALIM,DATAINC,ORIENTATION,'Position',RECT)
%   adds a color scale to the current figure.  The color scale uses the part
%   of the figure's colormap specified by limits in the 1-by-2 vector
%   CMAPLIM.  The ticks on the vertical axis are in physical data units which
%   may be scaled and shifted with respect to the colormap indices and are
%   controlled by DATALIM and DATAINC.  DATALIM is a 1-by-2 vector such that
%   DATALIM(1) and DATALIM(2) indicate the physical values corresponding to
%   the colors in rows CMAPLIM(1) and CMAPLIM(2), respectively, of the
%   colormap.  DATALIM and DATAINC are in physical data units.  DATALIM(2)
%   must exceed DATALIM(1), but CMAPLIM(2) may be less than CMAPLIM(1).
%   ORIENTATION should be either 'horiz' for horizontal or 'vert' for vertical.
%   RECT = [left, bottom, width, height] specifies the location and size of
%   the axis box containing the color scale (i.e., the 'Position' property
%   of the axes containing the color scale).  Unlike COLORBAR, COLORSCALE
%   does not automatically decide where to place the axes.  COLORSCALE
%   optionally returns the axes handle.
%
%   H = COLORSCALE(...,PROP1,VAL1,PROP2,VAL2,...) sets additional
%   properties of the axes containing the color scale.
%
%   Example
%   -------
%       % Create a figure with a jet colormap
%       figure
%       colormap jet
% 
%       % Create a standard colorbar
%       set(axes,'Visible','off')
%       bar = colorbar;
%       set(get(bar,'Title'),'String','Standard Colorbar')
%       pos = get(bar,'Position');
% 
%       % Create a terrain height scale using part of the colormap
%       colorscale([31 54], [0 9000], 1000, 'vert',...
%                  'Position',pos - [0.7 0 0 0])
%       title('Terrain Height')
%       ylabel('elevation above sea level, meters')
% 
%       % Create a bathymetry scale that uses a different part of the
%       % colormap and runs in reverse (i.e., CMAPLIM(1) > CMAPLIM(2)).
%       colorscale([24 1], [0 12000], 1000, 'vert',...
%                  'Position',pos - [0.35 0 0 0],'YDir','reverse')
%       title('Bathymetry')
%       ylabel('depth below sea level, meters')
%
%   See also COLORBAR, COLORMAP, COLORMAPEDITOR, AXES.

%   Rob Comer 7-3-2002
%   Copyright 2002 The MathWorks, Inc. 

error(nargchk(6,inf,nargin));

cmaplim = varargin{1};
datalim = varargin{2};
datainc = varargin{3};
orientation = varargin{4};

% Determine tick labels
tickvalues = datainc * [ceil(datalim(1)/datainc) : floor(datalim(2)/datainc)];
for i = 1 : length(tickvalues)
  ticklabel{i} = num2str(tickvalues(i));
end

% Determine tick positions and image array
if cmaplim(1) < cmaplim(2)
    tick = cmaplim(1) + (tickvalues - datalim(1)) * diff(cmaplim) / diff(datalim);
    I = cmaplim(1):cmaplim(2);
    ilim = cmaplim;
else
    tick = cmaplim(2) - (tickvalues - datalim(1)) * diff(cmaplim) / diff(datalim);
    I = cmaplim(1):-1:cmaplim(2);
    ilim = [cmaplim(2) cmaplim(1)];
end

% Create the color bar axes and image object
h = axes('Visible','off');
if ~isempty(strmatch(lower(orientation),'vertical'))
    % Vertical scale
    image(I','CDataMapping','direct','YData',ilim);
    set(h,'YTick',tick,...
          'XTick',[],...
          'YTickLabel',ticklabel);
else
    % Horizontal scale
    image(I,'CDataMapping','direct','XData',ilim);
    set(h,'XTick',tick,...
          'YTick',[],...
          'XTickLabel',ticklabel);
end

% Set axes additional properties
set(h,'YDir','normal'); % Override the default YDir set by IMAGE
set(h,varargin{5:end}); % Separate in case we have {...,'YDir','reverse',...}
set(h,'Visible','On');  % Always make it visible

% Set return value, if any
if nargout == 1
    varargout{1} = h;
end

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