Discover MakerZone

MATLAB and Simulink resources for Arduino, LEGO, and Raspberry Pi

Learn more

Discover what MATLAB® can do for your career.

Opportunities for recent engineering grads.

Apply Today

Thread Subject:
Very strange alphadata problem

Subject: Very strange alphadata problem

From: Patrik

Date: 24 Sep, 2009 12:06:04

Message: 1 of 6

I have a weird problem concerning the alphadata property of an image. If I set the alphadata like:

set(imageHandle,'Alphadata',0.5)

the x- and y-axis labels are mirrored (the numbers are actually mirrored as if you were looking on the screen through a mirror), and only half the image is shown, the bottom half is white. By resizing the figure window the bottom half of the image appears above and slightly ontop of the top half. What the h*ll is going on?

I'm using windows xp sp2, R2007a with an ATI Radeon X1300/X1500 graphics card.

Subject: Very strange alphadata problem

From: Rune Allnor

Date: 24 Sep, 2009 12:18:35

Message: 2 of 6

On 24 Sep, 14:06, "Patrik " <patrik_brynolfs...@yahoo.com> wrote:
> I have a weird problem concerning the alphadata property of an image. If I set the alphadata like:
>
> set(imageHandle,'Alphadata',0.5)
>
> the x- and y-axis labels are mirrored (the numbers are actually mirrored as if you were looking on the screen through a mirror), and only half the image is shown, the bottom half is white. By resizing the figure window the bottom half of the image appears above and slightly ontop of the top half. What the h*ll is going on?
>
> I'm using windows xp sp2, R2007a with an ATI Radeon X1300/X1500 graphics card.

Please post a code example that replicates the effect.

Rune

Subject: Very strange alphadata problem

From: Patrik

Date: 24 Sep, 2009 12:54:01

Message: 3 of 6

Well it isn't very much more than in my first post. The variable "image" can be any 2D image or matrix.

image = rand(384);
h = imagesc(image);
set(h,'AlphaData',0.5)

That's it.

Subject: Very strange alphadata problem

From: Michael Garrity

Date: 24 Sep, 2009 13:00:23

Message: 4 of 6

"Patrik " <patrik_brynolfsson@yahoo.com> wrote in message news:h9fnbc$clp$1@fred.mathworks.com...
>I have a weird problem concerning the alphadata property of an image. If I set the alphadata like:
>
> set(imageHandle,'Alphadata',0.5)
>
> the x- and y-axis labels are mirrored (the numbers are actually mirrored as if you were looking on the screen through a mirror),
> and only half the image is shown, the bottom half is white. By resizing the figure window the bottom half of the image appears
> above and slightly ontop of the top half. What the h*ll is going on?
>
> I'm using windows xp sp2, R2007a with an ATI Radeon X1300/X1500 graphics card.
>
The alpha flipped your renderer to OpenGL. We've seen a particular
graphics card driver version where glBitmap (the command that is
used to implement text in OpenGL) is exactly backwards. I'm sorry,
but I don't remember the details of the version numbers, but I would
suggest upgrading/downgrading your driver. Also, as always, pass
details on to support.

    -Mike Garrity
    -The MathWorks

Subject: Very strange alphadata problem

From: Camille Couzi

Date: 22 Dec, 2010 15:29:07

Message: 5 of 6

Hi Patrik and Mike Garrity,

I know that this is very old post, but I am having the same problem of x and y tick lables mirrored when using alphadata.
Please can you tell me what was the solution, what do I have to do on my renderer?

Thanks in advance for your suggestions and help

Camille.

Subject: Very strange alphadata problem

From: Sim

Date: 21 Nov, 2011 14:02:10

Message: 6 of 6

"Camille Couzi" <camillecouzi@yahoo.fr> wrote in message <iet5g3$knj$1@fred.mathworks.com>...
> Hi Patrik and Mike Garrity,
>
> I know that this is very old post, but I am having the same problem of x and y tick lables mirrored when using alphadata.
> Please can you tell me what was the solution, what do I have to do on my renderer?
>
> Thanks in advance for your suggestions and help
>
> Camille.

I have the same problem with an ATI card. The workaround is the following:

gl = opengl('data');
if strfind(gl.Vendor,'ATI')
    opengl('software')
end

Simon

Tags for this Thread

What are tags?

A tag is like a keyword or category label associated with each thread. Tags make it easier for you to find threads of interest.

Anyone can tag a thread. Tags are public and visible to everyone.

Contact us