Multiple Colormaps, freezeColors won't work
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Hi,
I am trying to use one image as a background, and one image in the foreground with transparency. I have acomplished this, but I need to use colormap(gray) for the background and colormap(jet) for the foreground. These images are arrays of data in an unknown range.
Currently, the code works except that the background is not in grayscale.
I have tried freezeColors, and it does not work.
Thanks
hold on
imagesc(handles.bg,'Parent',movie_scrn)
colormap(gray)
hold off
colormap(jet)
hold on
tmpImg = image(handles.cmosData(:,:,frame),'Parent',movie_scrn);
alphaMap = handles.cmosData(:,:,frame) >= handles.minVisible;
set(tmpImg, 'AlphaData', alphaMap);
2 comentarios
Respuesta aceptada
Oliver Woodford
el 16 de Jun. de 2011
Use real2rgb to convert your data matrices to images, and do the alpha matting in software by combining them as follows:
G = real2rgb(handles.bg, 'gray');
J = real2rgb(handles.cmosData(:,:,frame), 'jet');
A = real2rgb(handles.cmosData(:,:,frame) >= handles.minVisible, 'gray');
I = J .* A + G .* (1 - A);
image(I, 'Parent', movie_scrn);
2 comentarios
Más respuestas (2)
Alex Taylor
el 16 de Jun. de 2011
Hi,
The issue here is that in the MATLAB graphics system, the 'colormap' is a property of the figure, meaning that you can only display grayscale images with one colormap per figure.
The workaround is to use the MATLAB function ind2gray to convert your grayscale images to RGB images. You will then be able to display both RGB image in the same figure with your desired coloring.
2 comentarios
Walter Roberson
el 16 de Jun. de 2011
ind2rgb is not appropriate for this situation, at least not by itself. JRJ has a pure data matrix that is getting converted to a plot via imagesc(), which is doing data range translation and rescaling.
Alex Taylor
el 16 de Jun. de 2011
Walter, yes, you are right. I was focusing my attention on the "why isn't the grayscale colormap being honored" part of the question. I wasn't attempting to provide a complete solution.
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