Real time logo detection in live camera preview with OpenCV on Android

Question

I am new to computer vision but I am trying to code an android app which does the following:

Get the live camera preview and try to detect one logo in that (i have the logo in my resources). In real-time. Draw a rect around the logo if found. If there is no match, dont draw the rectangle.

I already tried a couple of things including template-matching and feature detection using ORB.

Why that didnt work:

Template-matching: Issues with scaling and rotation. I tried a multi scale variant of it but a) the performance was really bad and b) the rectangle was of course always shown trying to search for the image. There was no way to actually confirm in the code if the logo was found or not.

ORB feature detection: Also pretty slow (5-6 fps) but it worked ok-ish. The other problem was that also i never could be sure if the logo was in the picture or not. ORB found random matches even if the logo was not in the picture.

Like I said, I am very new to this. I would appreciate the help on what would be the best way to achieve:

• Confirm if a picture A (around 200x200 pixels) is in ROI of camera picture (around 600x600 pixels).

• This shouldnt take longer than 50ms per frame. I dont know if thats even possible though. So if a correct way to do this would take a bit longer than that, I would just do the work in a seperate thread and only analyze like every fifth camera frame or so.

Would appreciate any hints or code examples on how to achieve that. Thank you!

Answer 1

With logo detection, I would highly recommend using OpenCV HaarClassifier. It is easy to generate training samples from a collection of images of the logo, or one logo image with many distortions.

If you can use a few rules like the minimum and maximum size of the logo to be detected, and possible regions on the image where it can appear, you can run the detector at a speed better than you mention with ORB.