[英]How can I draw the rectangle including the surfPoints object on the image?
I have a grayscale image I want to extract the regions of interest using detectSURFFeatures().我有一个灰度图像,我想使用 detectSURFFeatures() 提取感兴趣的区域。 Using this function I get a surfPoints object.
使用这个 function 我得到一个 surfPoints object。 by displaying this object on the image I get circles as regions of interest.
通过在图像上显示此 object,我将圆圈作为感兴趣的区域。 For my case I want the rectangular areas encompassing these circles.
就我而言,我想要包含这些圆圈的矩形区域。 To be more clear i have a image 1:
为了更清楚,我有一张图片1:
I want to extract Region of Interest (ROI) using: detectSURFFeatures(), we obtain the image我想使用:detectSURFFeatures() 提取感兴趣区域(ROI),我们获得图像
if you can see we have circular region, and for my case i want the rectangular ROI that contains the circular region:如果你能看到我们有圆形区域,对于我来说,我想要包含圆形区域的矩形 ROI:
It looks like the radius is fully determined by the points.Scale
parameter.看起来半径完全由
points.Scale
参数决定。
% Detection of the SURF features:
I = imread('cameraman.tif');
points = detectSURFFeatures(I);
imshow(I); hold on;
% Select and plot the 10 strongest features
p = points.selectStrongest(10)
plot(p);
% Here we add the bounding box around the circle.
c = 6; % Correction factor for the radius
for ii = 1:10
x = p.Location(ii,1); % x coordinate of the circle's center
y = p.Location(ii,2); % y coordinate of the circle's center
r = p.Scale(ii); % Scale parameter
rectangle('Position',[x-r*c y-r*c 2*r*c 2*r*c],'EdgeColor','r')
end
And we obtain the following result:我们得到以下结果:
In this example the correction factor for the radius is 6
.在这个例子中,半径的修正系数是
6
。 I guess that this value correspond to half of the default Scale propertie's value of a SURFPoints
object (which is 12.0
).我猜这个值对应于
SURFPoints
object (即12.0
)的默认 Scale 属性值的一半。 But since there is no information about that in the documentation, I can be wrong.但由于文档中没有关于此的信息,我可能是错的。 And be carreful, the scale parameter of each ROI is not the same thing as the scale propertie of a
SURFPoints
object.请注意,每个 ROI 的比例参数与
SURFPoints
object 的比例属性不同。
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