在MATLAB中设置colorbar的alpha值R2015b

Question

我想在我的图中设置一些透明度，我可以用alpha来做。这很好，但我也想调整颜色条。以下是一个示例：

subplot(2,1,1) 
A = imagesc(meshgrid(0:10,0:5)); 
alpha(A,1) 
colorbar 

subplot(2,1,2) 
B = imagesc(meshgrid(0:10,0:5)); 
alpha(B,.1) 
colorbar 

该示例摘自here。在这个页面上有两个解决方案，但没有适用于Matlab R2015b。

Answer 1

随着HG2图形（R2014b +），你可以得到一些无证底层情节的对象，并改变透明度。

c = colorbar(); 

% Manually flush the event queue and force MATLAB to render the colorbar 
% necessary on some versions 
drawnow 

alphaVal = 0.1; 

% Get the color data of the object that correponds to the colorbar 
cdata = c.Face.Texture.CData; 

% Change the 4th channel (alpha channel) to 10% of it's initial value (255) 
cdata(end,:) = uint8(alphaVal * cdata(end,:)); 

% Ensure that the display respects the alpha channel 
c.Face.Texture.ColorType = 'truecoloralpha'; 

% Update the color data with the new transparency information 
c.Face.Texture.CData = cdata; 

你必须要小心，这样做的彩条是不断刷新，这些变化不会粘。为了让他们留下来，而我打印的身影，我只是改变了Face的东西的ColorBinding模式除了interpolated

c.Face.ColorBinding = 'discrete'; 

这意味着，当你改变颜色限制或颜色表也不会被更新。如果您想更改其中的任何一项，则需要将ColorBinding重置为intepolated，然后再次运行上述代码。

c.Face.ColorBinding = 'interpolated'; 

例如，以下将与一个透明颜色条保存的图像两个色彩映射表：

c = colorbar(); 

drawnow; 

alphaVal = 0.1; 

% Make the colorbar transparent 
cdata = c.Face.Texture.CData; 
cdata(end,:) = uint8(alphaVal * cdata(end,:)); 
c.Face.Texture.ColorType = 'truecoloralpha'; 
c.Face.Texture.CData = cdata; 

drawnow 

% Make sure that the renderer doesn't revert your changes 
c.Face.ColorBinding = 'discrete'; 

% Print your figure 
print(gcf, 'Parula.png', '-dpng', '-r300'); 

% Now change the ColorBinding back 
c.Face.ColorBinding = 'interpolated'; 

% Update the colormap to something new 
colormap(jet); 

drawnow 

% Set the alpha values again 
cdata = c.Face.Texture.CData; 
cdata(end,:) = uint8(alphaVal * cdata(end,:)); 
c.Face.Texture.CData = cdata; 

drawnow 

% Make sure that the renderer doesn't revert your changes 
c.Face.ColorBinding = 'discrete'; 

print(gcf, 'Ugly_colormap.png', '-dpng', '-r300');