dzvrt's profile - activity

I am familiar with them, but the problem is that I have an object on the image (my ROI) that I want to rotate. If I rotate the image using the above mentioned functions, the object on the rotated image is rotated as well for some strange angle, and not the desired one. This happens because because I'm rotating the image, but how can I achieve to rotate the object for a specific angle? I guess not by rotating the entire image?

Thanks for the ideas, I'll think about them.

Thanks for the code. I'll analyze it to understand how it works.

How does rotation in OpenCV work? I have a ROI in the image that I would like to rotate for a certain angle, and I move it to the top left corner of the image as a center of rotation. Then I move ROI back to the old position to see its new position. But the result I get is ROI under some strange angle. Can someone explain me how the rotation works?

I think that my problem is that once I start working with a big image, I apply the affine transform on the entire image, and then as I result I obtain another big image. Then if I continue applying transformations on the big image, I consider the coordinate system of the big image and that's why the problem happens. Is there a way to translate the coordinate system to the image (or the image is translated to the coordinate system) so that the image can be visible? The problem is that after the affine transform, I don't have any control of the position of the translated image.

I applied all your suggestions and after I reset the ROI, I apply the transformation on the big image. Then, I display the new image which now has the same size as the big image, but I still can't see the results of my transformation (the image is black).

I have an image on which I apply affine transforms (several of them in a row). The problem is that after executing them, sometimes happens that parts of the transformed image go outside of the view window and are not visible (as a result of the transformation). To make things worse, I use the transformed image to apply other affine transforms on it, but since the invisible part is lost, these transforms are not applied on it. Any suggestions how to recover the lost image part due to affine transformation? Thanks

Thanks! :)

If I apply your suggestion, then will the color of the pixels within the shape, correspond to the color of the original image pixels? It is very important to preserve this information.

Thanks, it was a good starting point. Actually I was thinking about something like this http://nashruddin.com/OpenCV_Circular_ROI , where the region of interest can be a circle, ellipse or any shape. The only thing in this solution not suitable for my case, is that the extracted circle patch has a color, and I would like to be just an image part. Do you have any suggestions for this?

Hi,

How can I extract a patch from an image, by knowing the image file to which it belongs? The patch is given with its center (the patch has the shape of an ellipse), its orientation, its scale, and its affine transformation with respect to a unit circle, and a set of descriptors.Any hints or code sample? Thanks!