The axes color property can only be set to one solid color.
A workaround is to plot a patch with interpolated colors and to set the patch's size to match the axes' limits. By assigning a LimitsChangedFcn, you can automatically update the patch to match the axes limits any time the limits are changed.
% Create axes
fig = figure();
ax = axes(fig);
% Create interpolated patch
% You won't see the patch until the vertices are updated when the
% axes limits change. If you want to update the vertices right away,
% call updateAxesBackground(p) after creating the patch.
px = nan(1,4);
py = nan(1,4);
pc = [1 1 0 0];
p = patch('Faces', 1:4, ...
'Vertices', [px.',py.'], ...
'FaceVertexCData',pc.', ...
'FaceColor','interp', ...
'EdgeColor','none', ...
'Parent',ax);
% Assign a limitsChangeFunction so that when the axes limits are changed,
% the background patch updates its extents (here's the magic sauce)
ax.XAxis.LimitsChangedFcn = @(~,~)updateAxesBackground(p);
% Set colormap - here's where the colors come from
ax.Colormap = sky(256);
% Add other plots
hold on
area(ax,reshape(magic(10),[],1),'FaceColor',[.8 .8 .8])
function updateAxesBackground(p)
% update background patch to fill axes
% p is a patch handle.
if isgraphics(p) % skip if p no longer exists
ax = ancestor(p,'axes');
% Escape from recursion by ensuring limits don't change
originalLimits = [ax.XLim, ax.YLim];
returnLimits = onCleanup(@()set(ax,'XLim',originalLimits(1:2),'YLim',originalLimits(3:4)));
% Update vertices
px = ax.XLim([1 2 2 1]);
py = ax.YLim([2 2 1 1]);
p.Vertices = [px.',py.'];
end
end
