How to remove everything that is grey (127, 127, 127) from an image?

Hi,

I want to remove everything with the rgb color (127, 127, 127) from an image. I am using

externalMask = planta.img(:,:,1)==127 & planta.img(:,:,2)==127 &...
        planta.img(:,:,3)==127

to know where the grey pixels are.

I want to show the image and that the grey parts doesn't appear.

How can I do that?

Thanks in advance!

PS: I am using R2016a version.

Answer 1

[Walter Roberson]

mask = all(planta.img == 127, 3);
image(planta.img, 'AlphaData', 1-mask)

[Oliver Lestrange]

Is there a way of the grey parts just disappear intead of become white (0)?

[Walter Roberson]

Observe.

t = randi(250, 25, 2);
fill(t(:,1),t(:,2),'r');
hold on

img = imread('cameraman.tif');
mask = img < 32;
image(img, 'AlphaData', 1-mask);
colormap(gray(256))
hold off

In other words, the parts do just disappear, and what-ever is beneath shows through. What happens to be beneath in your experiment was white, possibly from the 'color' of the axes.

The figure has a color that is underneath any axes. The axes has a color that is underneath anything you draw. You might potentially also have one or more uipanel between the figure and the axes, and they each can have a color. You can set the 'color' of each of those to 'none'... but I doubt you will be able to get your desktop window underneath to show through.

[Oliver Lestrange]

Ok.

Thanks a lot!

[Image Analyst]

Need double equals:

mask = all(planta.img == 127, 3);

[Walter Roberson]

Good point