Daniel J Sebald skrev:
Søren Hauberg wrote:
John W. Eaton skrev:
It would be helpful to me if people who have been using the new
graphics features could check that I haven't broken too many things.
Please report any problems that you find to this list.
I've actually used octave today for some real work so I hit a few bugs:
*) The axis when showing images isn't correct. This was fixed in
previous version after some discussions on the behaviour. I think you
just have to flip the y-axis. The problem can be illustrated by the
following code:
im = zeros(50, 50);
im(30, 5:15) = 1;
im(25:35, 10) = 1;
imshow(im)
hold on; plot(10, 30, 'r*'); hold off
This should show a black image with a white cross. In the center of
the white cross a red * should appear.
Well, there may be an error there. I see some inconsistency using the
image(x,y,im) form. Not sure what the convention is. Note however
that the baby example of image comes out correct. Also, location
(x,y) in the matrix representation of the image doesn't necessarily
have to mean (x,y) in the plotting space. Many conventions have the
image with reference point at the top left (and some have bottom left,
unfortunately). If you can't supply a patch, let me know what the
convention should be.
I'm not quite sure I understand what you write, but I'll answer anyway :-)
I've executed the following commands in Matlab:
>> im = ones(40,60);
>> image(im)
>> xlabel('X')
>> ylabel('Y')
>> hold on; plot(0, 0, 'r*'); hold off % This plot doesn't show
>> hold on; plot(1, 1, 'r*'); hold off & This plot shows
This generates the image you can see at
http://hauberg.org/wiki/lib/exe/fetch.php?cache=cache&media=mlimplot.png
As you can see the vertical axis is the Y-axis and it corresponds to the
row coordinates in the "im" matrix. And the horizontal axis corresponds
to the column coordinates in the matrix.The origin of the coordinate
system is at the top-left point in the image. I'm plotting a * in both
(0,0) and (1,1) but only the one in (1,1) actually shows on the plot. So
the axis start in (1,1)
Did that answer you question?