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From: Matthew on 7 Apr 2010 15:19
I have two images, one acquired at a resolution of 128*128 pixels, and another sampled at 8*8 with a much lower resolution technique. Both display just fine separately using imagesc, but when I try to plot one, then use "hold on" the 8*8 image just plots in the corner of the 128*128 image. How can I get them to display across the same area? I could just make copies of the small image, but that is upsampling by replicating data, and just seems like a bad way to do it.

Please help. Thanks
From: ImageAnalyst on 7 Apr 2010 15:41
On Apr 7, 3:19 pm, "Matthew"
<matthew.merritt.nos...(a)utsouthwestern.edu> wrote:
> I have two images, one acquired at a resolution of 128*128 pixels, and another sampled at 8*8 with a much lower resolution technique. Both display just fine separately using imagesc, but when I try to plot one, then use "hold on" the 8*8 image just plots in the corner of the 128*128 image. How can I get them to display across the same area? I could just make copies of the small image, but that is upsampling by replicating data, and just seems like a bad way to do it.
>
> Please help. Thanks

---------------------------------------------------------------------
Why is that a bad way? Just do it.
Secondly, you'll have to average the images, or maybe play around with
the alpha channel, to get both to show up, otherwise one will
completely obscure the other.
From: Matthew on 29 Apr 2010 14:09
OK, I have upsampled my data so that it fits. But I am having a really hard time with alpha. I have read the help, but things aren't working the way I thought they would.

For example, I can issue pcolor(image_space) where image_space is a 64*64 matrix. But now these are the results I get of three different commands:

alpha(face_alpha,.3)
??? Undefined function or variable 'face_alpha'.

>> alpha('face_alpha',.3)
??? Error using ==> alpha at 47
Wrong number of arguments

>> alpha('face_alpha','flat')
??? Error using ==> alpha at 47
Wrong number of arguments

How can I use alpha to change the transparency?

Thanks


ImageAnalyst <imageanalyst(a)mailinator.com> wrote in message <8e4fccff-663f-4d1b-a053-fefe7d042a93(a)u22g2000yqf.googlegroups.com>...
> On Apr 7, 3:19 pm, "Matthew"
> <matthew.merritt.nos...(a)utsouthwestern.edu> wrote:
> > I have two images, one acquired at a resolution of 128*128 pixels, and another sampled at 8*8 with a much lower resolution technique. Both display just fine separately using imagesc, but when I try to plot one, then use "hold on" the 8*8 image just plots in the corner of the 128*128 image. How can I get them to display across the same area? I could just make copies of the small image, but that is upsampling by replicating data, and just seems like a bad way to do it.
> >
> > Please help. Thanks
>
> ---------------------------------------------------------------------
> Why is that a bad way? Just do it.
> Secondly, you'll have to average the images, or maybe play around with
> the alpha channel, to get both to show up, otherwise one will
> completely obscure the other.
From: ImageAnalyst on 29 Apr 2010 14:55
Well have you created your transparency array "face_alpha"? It looks
like NOT. It doesn't know what face_alpha is because you haven't
created it yet. Maybe you just want to put in a constant, like in
their example so that every pixel has the same transparency.
From: Matthew on 30 Apr 2010 09:54
OK, thanks for the help.

I have a further question. Is there a difference in between pcolor, contour, and imshow with the way they interact with alpha. I would really like to overlay a contour plot over an image, but I can't seem to change alpha for the contour plot, though I can with 2 images using imshow.


ImageAnalyst <imageanalyst(a)mailinator.com> wrote in message <b3749b87-2bc9-4ba1-93f5-c97905460171(a)k29g2000yqh.googlegroups.com>...
> Well have you created your transparency array "face_alpha"? It looks
> like NOT. It doesn't know what face_alpha is because you haven't
> created it yet. Maybe you just want to put in a constant, like in
> their example so that every pixel has the same transparency.
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