how to put all the png image properties?

Hello, this is my first post here, although I've been using matlab for a while. Here is my problem and I hope someone could help me : I want to show some PNG images on axes, within a GUI. I've managed to show it but some colors is changed. This is the original PNG image:

and in the axes I get this:

when I have this code:

axes(handles.walkonly);
elderlywalking= imread('elderlywalking.png');
Wonly=imshow(elderlywalking);
set(Wonly, 'AlphaData', elderlywalking(:,:,1));

The sky picture that you can see on the "background", is set for me, as a background of the whole project, so I prefer to not change it. I thought that may be I'm missing some of the original image datas. So I tried the next code:

% % % axes for "walkandcar" option% % %
axes(handles.walkANDcar);
[walkandcar, ~, alpha] = imread('walkandcar.png');
% walkandcar= imread('walkandcar.png');
WandC=imshow(walkandcar);
set(WandC, 'AlphaData', walkandcar(:,:,1));

but I keep on having the same image. From what I've been looking, combining the image can be an option, but I prefer to work on the axes and not as a single combined picture, because those images are the representation of an icon to be selected afterwards...

How can I solve it? Is it easier to combine the images ? thank you!

[Geoff Hayes]

dafniz91 - what are you calling the line of code

 set(Wonly, 'AlphaData', elderlywalking(:,:,1));

as this adds transparency to your graphics object (see Add Transparency to Graphics Objects for details. What happens if you remove this line of code?

[dafniz91]

hi Geoff I thought that I replied your comment but I think it didn´t load...

so sorry for my absense. I tried what you suggest but no results.... i got this image by adjusting transparency with different values.

as you can see it added "transparency" effectively, but that not what I want and also it added the black background.

do you have another idea of what can be done?

sorry for my english.

dafniz91

Answer 1

[Walter Roberson]

You need to create an ROI from the image that excludes the white parts. Then you need to fill the holes in that ROI using imfill('holes'), like

   BW = imfill(BW, 'holes');

and then

fg_alpha = double(BW);

Then

image(BackgroundImage)
hold on
image(ElderlyMatrix, 'AlphaData', fg_alpha)

this will use everything within the ROI as-is, but everything outside the ROI will show through the background image.

[dafniz91]

thank you! I will try that.