How do I find Waldo with Mathematica?
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How do I find Waldo with Mathematica?
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Re: How do I find Waldo with Mathematica?
#2At the time of writing this, the top answer has exactly 1337 upvotes.
Re: How do I find Waldo with Mathematica?
#3And here is the discussion mentioned https://news.ycombinator.com/item?id=3367865
Re: How do I find Waldo with Mathematica?
#4it makes me incredibly happy that the top answer is just a simple correlation - building a boltzman machine or svm is completely overcomplicating the problem. In the other thread the top comment echos that this is a common problem in CV (as in object detection) and goes into that process. But an important thing we ML practitioners should remember is that we're building toward a goal, and exercises like this can help put us back in our place when we see that simple is usually better.
Re: How do I find Waldo with Mathematica?
#5it makes me incredibly happy that the top answer is just a simple correlation - building a boltzman machine or svm is completely overcomplicating the problem. In the other thread the top comment echos that this is a common problem in CV (as in object detection) and goes into that process. But an important thing we ML practitioners should remember is that we're building toward a goal, and exercises like this can help…
It's important to note that the top answer is hand-tuned to work with that specific image. It probably doesn't generalize well.
Re: How do I find Waldo with Mathematica?
#6You could also prioritize your search area, assuming you're searching official Wheres Wally? images.
"53 percent of the time Waldo is hiding within one of two 1.5-inch tall bands, one starting three inches from the bottom of the page and another one starting seven inches from the bottom, stretching across the spread."
http://www.slate.com/articles/arts/culturebox/2013/11/where_...
Re: How do I find Waldo with Mathematica?
#7Interestingly, even though the top answer has 1337 upvotes, it appears none of those people checked whether the answer actually works. Either that, or Mathematica's algorithms have changed since Jan 2012.
Another commenter got me curious about just how hand-tuned the answer was, so I fired up Mathematica 8 and put their solution in. I had to dig up the original image using Wayback Machine (thanks, archive.org!) but then, to my surprise, their answer didn't actually work. It merely darkened the image uniformly, meaning it wasn't able to find any potential Waldos.
I fiddled around with their solution for a bit, and then finally just hooked their parameter up to a slider. I thought maybe the "level" parameter just needed a bit of tweaking. But surprisingly, it still doesn't work as advertised: http://i.imgur.com/XWNTvYU.jpg
Their "level" parameter was originally 0.12, but like I said, that didn't work at all. It doesn't work until the parameter is bumped up to 0.18, at which point it gives the wrong solution (the lower-left circle). Then, 0.19 gives another incorrect solution (the lower-right circle). Finally, 0.20 identifies Waldo.
So this solution is a nice way to filter out potential targets, but I wish I could figure out whether the original poster was being shady or whether Mathematica's internals changed since they posted their answer. I'm inclined to give them the benefit of the doubt, but that has me burning with curiosity about what exactly must've changed in Mathematica's implementation.
EDIT: I didn't do the most basic of checks: to make sure I didn't introduce any changes in the original experiment. It turns out by rehosting the image on imgur, it compressed the resulting image, introducing artifacts into the color channel. Their solution no longer worked as advertised due to this. That shows how brittle the solution is, though! I wonder if we can make it more robust without fundamentally rewriting it?
Re: How do I find Waldo with Mathematica?
#8You could also prioritize your search area, assuming you're searching official Wheres Wally? images. "53 percent of the time Waldo is hiding within one of two 1.5-inch tall bands, one starting three inches from the bottom of the page and another one starting seven inches from the bottom, stretching across the spread." http://www.slate.com/articles/arts/culturebox/2013/11/where_...
"53% of the time, Waldo appears in an empirically determined 25% of the page"
If you repeated this with random data, I expect you could find the same results: this does not constitute evidence that Waldo is placed in those bands with priority.
You can mathematically say that 100% of the time, Waldo appears in 0% of the page (defined by individual points rather than areas). This equivalent statement clearly has no predictive power.
In my opinion, it would not be reliable to use this on novel Waldo images.
Re: How do I find Waldo with Mathematica?
#9Interestingly, even though the top answer has 1337 upvotes, it appears none of those people checked whether the answer actually works. Either that, or Mathematica's algorithms have changed since Jan 2012. Another commenter got me curious about just how hand-tuned the answer was, so I fired up Mathematica 8 and put their solution in. I had to dig up the original image using Wayback Machine (thanks, archive.org!) but t…
The code works as-is in Mathematica 9 (though with the URL modified to point to archive.org), so there's likely a difference between your version of 8 and 9.0.0.0.
Re: How do I find Waldo with Mathematica?
#10Interestingly, even though the top answer has 1337 upvotes, it appears none of those people checked whether the answer actually works. Either that, or Mathematica's algorithms have changed since Jan 2012. Another commenter got me curious about just how hand-tuned the answer was, so I fired up Mathematica 8 and put their solution in. I had to dig up the original image using Wayback Machine (thanks, archive.org!) but t…
The code works as-is in Mathematica 9 (though with the URL modified to point to archive.org), so there's likely a difference between your version of 8 and 9.0.0.0.
Can you try http://i.imgur.com/WwQ8P5R.jpg instead of the archive.org link? I rehosted the image on imgur, but it looks like imgur re-compresses the jpg, resulting in differences in the image. If so, then that demonstrates just how brittle this solution is.
