Define a RGBa color- transparency

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!

[deeksha rastogi]

but what are the exact working of alpha matting and please write down its source code in matlab.

Answer 1

[Rini Varghese]

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!

Answer 2

[Dhanyatha]

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.

Answer 3

[Image Analyst]

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/

Answer 4

[Image Analyst]

You can now use labeloverlay to create transparent overlays.