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The average color of the New York City sky, updated every 5 minutes. (nskyc.com)
236 points by shashashasha on June 22, 2011 | hide | past | favorite | 37 comments

A clever idea, however his data source is irrevocably corrupted by the auto exposure and auto white balance of his webcam. The result is, sadly, more influenced by the algorithms in his camera than the sky itself.

Notice how there's some outrageous and short-lived tones during sunrise and sunset -- that's the white balance jumping around (Possibly an automatic saturation gain too?)

Then notice how the brightness doesn't peak and fall during the day, instead jumping quickly from darkness to "full" brightness with frequent dramatic shifts far greater than reality would allow. That's because the moving cloud cover is triggering the auto exposure to jump around incessantly.

The ideal fix would be to replace the webcam with a digital camera capable of tethered shooting and fully manual operation. You'd fix the shutter, aperture and ISO values to a level that minimizes clipping, set the white balance to daylight, and point the camera in a direction least likely to be in the sun's path (in the southern hemisphere, that's south).

In order to capture the dynamic range fully, you could allow the camera to automatically choose the shutter speed, then compensate in the algorithm by reading the shutter speed from the EXIF data.

That said, full points for the idea, and for a great web app to visualize the data!

Notice how there's some outrageous and short-lived tones during sunrise and sunset -- that's the white balance jumping around (Possibly an automatic saturation gain too?)

The ones at sunrise are weird (blue throws off the white balance) but the sunset ones are actually accurate-- that's the color of a NY sunset in the summer. Surreal, eh?

I miss New York.

How I wish more grad students dissected empirical data like this!

Some webcams have manual settings, I know mine does. Just enabling those should get you 90% of the way of a tethered digital camera, "all that remains" is getting sufficient dynamic range and fixing the curves/compensating for human perception.

Many cheap/consumer devices let you disable some automatic adjustment, but rarely do they let you disable everything. For example, I've seen webcams that can fix the white balance but have automatic saturation adjustment that can't be turned off.

The cheap option that comes to mind would be an old and/or second hand Canon PowerShot capable of running CHDK firmware. Ask friends and family; you'd probably be able to score one free from a dusty cupboard draw.

I think the word you are looking for is irreparably, not irrevocably.

And it looks like, more than the auto-white balance thing, he's getting washed-out skies from overexposure. This is a very common problem in photography- ever take a photo somewhere with a blue sky dotted with clouds but in the photo the sky comes out solid white or gray? Go back and look at some of your old photos, you will notice it.

There is no easy solution without sacrificing exposure of the lower half (what is usually the subject) however in this case the subject IS the sky, so select a camera that has manual exposure, set it a little lower and you'll be all right.

Good insight... but New York City is in the northern hemispshere.

Yeah, which is why I qualified it. I assume it's the opposite and the sun drops to the south in a northern winter, but I simply don't know if my assumption is right.

Yup, I live in northeast USA and the sun has a distinct southern slant even in summer. In winter it hardly gets over the trees.

The average color of the Seattle sky, updated every 5 minutes: #DDDDDD

#DEDEDE every now and then when a Boeing plane flies over the camera.

It must be hard to sleep at night with all that light.

I'm moving to Seattle in 2 days - looking forward to it, although I'm going to miss Mr. Blue Sky.


I always wanted to make a wall-sized version of this with really bright LEDs-- kind of like a light therapy box, but programmed with the full progression of color and brightness of various locations and seasons around the world - summer in NYC, Paris in the springtime, New England in the winter, LA on a non-smoggy day, etc., with options for real-time data feeds, too.

So you could feel like you were in the best location in the world on the best day of the year. Or just synchronize your work/sleep schedule with some other timezone.

Small versions as nice gifts, big custom versions for the luxury/institutional market. Chumby app. Wall mounted LCD/LED and/or LED dome projection.

Any hardware hackers feel like pairing up? I'm a short flight from Shenzhen. ;)

You could definitely sell these I reckon.

If the size of each block was reduced to a few pixels square you could fit an entire year in a single image (4 pixels * 12 * 24 = 1152 wide, 365 * 4 = 1460 high) - which might be nice way of visualizing what the weather is like in a location.

If you were making the blocks that small, I'd make the axis meaningful and go 365 blocks across -- one column for each day of the year -- then midnight to midnight from top to bottom.

This would be a great visualization of daylight quantity and quality over the year.

A similar visualization to what you're talking about is an old project by Lee Byron: http://www.leebyron.com/what/daylight/

Yeah - that's similar to what I had in mind, I don't know if making it bigger would show the effects of weather more.

What those do show is:

- The huge variations in day length due to latitude

- How those of us in higher latitudes spend in the gloaming - my favourite time of day

When I used to work in building design, I used to create lots of charts of various climate data for projects in new regions where I didn't know much about the climate (and also for eye candy in presentations). One of those charts was very similar to what you suggested. Basically a 2D array of coloured squares, with hour of the day along one axis and month of the year along the other. Then each square would be coloured according to the average solar radiation falling at that time of day in that month (using a blue-green-red type scale usually, but you can do grey scale or anything else you can think of). It was a useful way of visualising lots of stuff - variation in day length, strength of the sun, summer/winter variations, etc.

You can plot other variables like this too - temperature, humidity, ...

Clever idea - I think it would be even better with some thinner lines (either vertical or horizontal) like http://moviebarcode.tumblr.com/

This would more closely match the progression of time, instead of making rows of squares.

Brilliant idea! The site is a little slow, so in case it didn't work for you first time, mouse over each panel to see the actual photo that was used for the avg color calculation.

I'm often looking for color inspiration, so will use this. Would be amazing to have this for Colorado skies, especially as the sun sets over the Rockies.

It would be pretty cool if he it make his could available on github so others could do the same at their cities.

I looked around. and found this http://jsfiddle.net/xLF38/

Hope it's helpful.

a bug fix:

`document.body.style.backgroundColor = 'rgb('+rgb.r+','+rgb.b+','+rgb.g+')';`

should be

`document.body.style.backgroundColor = 'rgb('+rgb.r+','+rgb.g+','+rgb.b+')'; `

Weirdly on that demo it derived an average color of green even though the pic looked to be 80% blue.

hence the fix.

I'd love for a way to interface with this site. Perhaps something that let's me get the current color and update my website's background color with it.


Great idea. Its already gone viral :) It might be better if you provide thin strips of each color rather than whole thumbnails as it can more accurately tell hows the skys colors is changing

Pretty cool. Might base my next color palette off of this.

That looks terribly depressing to me. Just saying.

Should totally add thumbnails. The mouseover would be more convenient for users and bandwidth costs would be lower.

Or maybe they already are thumbnails, and the site is suffering from the Hacker News effect... =o

At which color balance though?

If it's auto color balance, it's completely useless.

Interesting. Not sure why this on the front page unless I'm missing something very important, but interesting

I like it because it is different (Inspiring maybe?), and it is someone's hacky project. Maybe a bit simple, but fits in IMO.

It is on the front page because it got a sufficient amount of upvotes in a short time.

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