Define a RGBa color- transparency

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Simon
Simon 2014-7-3
回答： Image Analyst 2022-11-8
Dear all,
is there a workaround to create, for example, a transparent yellow? Apparently Matlab colormap only works with RGB notations, not RGBa. My idea was: trans_yellow=[1 1 0 0.5] I want to define a transparent color, just changing the alpha value for the whole plot does not work for me.
Thanks!
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deeksha rastogi
deeksha rastogi 2016-12-31
移动：DGM 2022-11-8
but what are the exact working of alpha matting and please write down its source code in matlab.

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回答（4 个）

Rini Varghese
Rini Varghese 2016-4-5
You can modify most object colors with 4 input arguments (RGBa notation) in MATLAB (2015). E.g. rectangle(x,y,w,h,'facecolor',[0 1 0,0.08]) will yield a transparent green box. Hope this helps!
Dhanyatha
Dhanyatha 2014-7-3
编辑：Dhanyatha 2014-7-3
Currently, the colormap function does not accept more than 3 arguments. However,you can use the TIFF class in MATLAB to specify the alpha parameter for the image.
Refer to this link for an example on how to create a TIFF object with transparency.
To read RGBA image, you can use readRGBAImage(),readRGBATile() or readRGBAStrip() functions. These functions reads image data as RGB, with associated alpha parameter.
Image Analyst
Image Analyst 2014-7-3
Perhaps - take a look at Steve's blog and see if it's what you want: http://blogs.mathworks.com/steve/2009/02/18/image-overlay-using-transparency/
Image Analyst
Image Analyst 2022-11-8
You can now use labeloverlay to create transparent overlays.

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