image rotation by application of a 2D rotation matrix

4 次查看（过去 30 天）
Nastassja Riemermann
回答： KSSV 2019-3-27
I'm working on a homework assignment where we have to rotate a .png image using three successive shear transformations with homogenous coordinates, and that worked fine. Next we're supposed to achieve the same rotation using "a single 2D rotation matrix", which I assume means using non-homogenous coordinates, and I got the following error:
Error using *
MTIMES (*) is not fully supported for integer classes. At least one argument must be scalar.
Error in problem0614 (line 20) imge = rotation*imga;
Can someone help me figure out the proper way to do this? My code is below:
function problem0614()
clc;
imga=imread('coins.png');
figure;
% imshow(imga);
theta=pi/4;
a = -tan(theta/2);
b = sin(theta);
shear1 = [1 a 0; 0 1 0; 0 0 1];
shear2 = [1 0 0; b 1 0; 0 0 1];
T1 = maketform('affine', shear1);
T2 = maketform('affine', shear2);
imgb = imtransform(imga,T1);
imgc = imtransform(imgb,T2);
imgd = imtransform(imgc,T1);
% imshow(imgb);
% imshow(imgc);
% imshow(imgd);
rotation = [cos(theta) -sin(theta); sin(theta) cos(theta)];
imge = rotation*imga;
imshow(imge);

请先登录，再回答此问题。

回答（1 个）

KSSV
KSSV 2019-3-27
You cannot work like that...you need to get locations of pixels and then multiply these locations to the rotation matrix. YOu may refer this link for the same question.
https://stackoverflow.com/questions/19684617/image-rotation-by-matlab-without-using-imrotate

类别

在 Help Center 和 File Exchange 中查找有关 Geometric Transformation and Image Registration 的更多信息

标签

产品


版本

R2018b

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by