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matlab 学习之一

花匠小妙招
2024-12-13 19:34

关于在自然图像上画散点的操作

显示首先得显示图像

figure

imshow（‘img’）

hold on %这个很重要，要不然接下来的画图操作就不会画在自然图上了。

for i=1:numel(x)
a(i) = floor(x(i)/640);
b(i) = x(i) - a(i)*640;
end
plot(a,b,'r.');
set(gca,'xlim',[0,639]); %设置x方向的坐标
set(gca,'ylim',[0,479]); %设置y方向的坐标
hold off

关于获得图像的句柄(handle)

昨天上网查了好久也没对获得图像的句柄看出个所以然来，忽然灵机一动原来可以这样获得句柄

handle = imshow('img');

然后再对这个句柄去操作。

我接下来的操作是进行鼠标在图像上滑过可以实时显示图像的坐标，

代码如下：

可以采用调用下面的函数来实现这一功能

dypoint(handle); %只需要传递一个参数

（转载的）

function dynpoint(arg,h)
% Show the coordinates of a plot dynamically
%
% To start use:
% dynpoint(h)
% where h is a handle to a figure, axes or e.g. line.
%
% To delete use:
% dynpoint('delete',h)
% where h is a handle to a figure, axes or e.g. line.
% (you may also use: dynpoint delete)
%
% There can only be one dynamic plotter in a figure at a time.
%
% Example:
% subplot(211), hline = plot(sin(1:10))
% subplot(212), plot(sin(1:100))
% dynpoint(hline)

% 2002,6.29

if ~exist('arg','var')
arg = gcf;
end

if ~isstr(arg)
handle = arg;
arg = 'init';
end

switch arg
case 'init'
if ~ishandle(handle)
error('h is not a handle')
end

[h,ax] = h2hax(handle);

% delete old dynamic text object
ht = findobj(h,'tag',[mfilename '_text']);
if any(ht)
delete(ht)
end

% text window at the bottom left corner
% text in centred
uicontrol(h,...
'style','text',...
'pos',[2 2 200 15],...
'tag',[mfilename '_text'],...
'userdata',ax(1))

% do the dynamic thing...
set(h,'windowbuttonmotionfcn',[mfilename ' move'])

case 'move'
ht = findobj(gcbf,'tag',[mfilename '_text']);
ax = overobj('axes');
if ~any(ax)
ax = get(ht,'userdata');
end
p = get(ax,'currentpoint');
set(ht,'string',sprintf('(%g, %g)', p(1), p(3)));

case 'delete'
if ~exist('h','var')
h = gcf;
end
[h,ax] = h2hax(h);
set(h,'windowbuttonmotionfcn','')

ht = findobj(h,'tag',[mfilename '_text']);
delete(ht)

end

% ----------
function [h,ax]=h2hax(handle)

typ = get(handle,'type');
if strcmp(typ,'figure')
h = handle;
ax = findobj(h,'type','axes');
elseif strcmp(typ, 'axes')
h = get(handle,'parent');
ax = handle;
elseif strcmp( get(get(handle,'parent'), 'type'), 'axes' )
ax = get(handle,'parent');
h = get(ax,'parent');
end