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Show HN: API for detecting people, cars, and everyday objects in images

dextrorobotics.com

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Re: Show HN: API for detecting people, cars, and everyday objects in images

#42

Post by cookingrobot »

ahc wrote: post #40

It'd be great if you could use this to detect nudity. Any plans for that? I'm assuming the balls on the "in the works" list are of the sport variety? ;) In the works: Shoes Balls Smartphones and tablets Dogs Keyboards Cups and glasses Doors Keys

https://github.com/pa7/nude.js

Re: Show HN: API for detecting people, cars, and everyday objects in images

#46

Post by tunnuz »

jluan wrote: post #25
tunnuz wrote: post #21

Earlier quoted context omitted.

The browser demo page says "Dextro supports up to 4 objects to be detected concurrently when used via the full API.", I think that's the problem.

Hey tunnuz and limejuice, sorry to hear we only picked up on 4 of the planes. We've biased our service towards precision rather than recall; thus, we try to be wrong about detected objects as little of the time as possible at the expense of perhaps missing a few object instances. I want to clarify: the 4 object concurrent detection refers to 4 classes of objects. On the Experiment page, you can only choose one class…

Ok, so the two 4s have nothing to do with each other. Thanks for the clarification.

Re: Show HN: API for detecting people, cars, and everyday objects in images

#47

Post by ank286 »

This is not Pedro Felzenszwalb's discriminative part-model algorithm. This is simple AdaBoost. The authors have labeled a bunch of datasets (1000s of them) and are able to detect whatever object. AdaBoost (Viola/Jones) is the most popular Yes/No detector, there is an OpenCV api for it. It used for detecting faces and license plates in commercial applications. Full person detector is nothing but a SVM+HOG descriptor.

As a computer vision researcher, I am not impressed by this. It is primarily an api for smartphone app makers who want a binary result for detection. It does not help with scene context analysis. For instance, if I have a big picture of a airplane on a wall, it will detect the airplane.. Does it know that this airplane is in the sky? or on a wall? There are a 1000 failure cases.

Re: Show HN: API for detecting people, cars, and everyday objects in images

#48

Post by apu »

Looks like this is using training data from the PASCAL VOC object detection challenge [1], which is the standard benchmark for evaluating object detection performance in computer vision.

Object detection is an extremely tough problem (some would say it is the computer vision problem ;-)), and while we've made a lot of progress in the past decade, the best methods are still terrible [2] -- average detection precision between 30-50%. For reference, most consumer applications require an AP of 90+% to be considered usable.

So if this is a completely automated solution, it's not going to be able to do much better, unless the creators can make massive (I mean orders-of-magnitude) improvements on the state-of-the-art.

But that being said, there are some applications where lower performance is acceptable. And if you add some manual verification, you could conceivably make this much better (with an increase in latency, though). Another possibility is to specialize on a certain type of input image (e.g., if you're a company taking photos in your warehouse, where all your photos look very similar and/or you can control the lighting and environment).

Still, I'm excited to see companies attempting to take object detection out to the real world. All the best to these guys!

[1] http://pascallin.ecs.soton.ac.uk/challenges/VOC/

[2] http://pascallin.ecs.soton.ac.uk/challenges/VOC/voc2011/resu...

Re: Show HN: API for detecting people, cars, and everyday objects in images

#49

Post by DenisM »

ank286 wrote: post #47

This is not Pedro Felzenszwalb's discriminative part-model algorithm. This is simple AdaBoost. The authors have labeled a bunch of datasets (1000s of them) and are able to detect whatever object. AdaBoost (Viola/Jones) is the most popular Yes/No detector, there is an OpenCV api for it. It used for detecting faces and license plates in commercial applications. Full person detector is nothing but a SVM+HOG descriptor.…

A bit off-topic, but... can you recommend a library or a service to recognize license plates? Thanks!
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