Why space matters: Imaging satellite operations, part 18—“Look at the stars, look how they shine for you…”

“…Yeah, they were all yellow.”

So, a small confession before continuing:  One of the reasons you haven’t seen any lessons for the past few weeks regarding the imagery colors is because I’ve been stuck on this color thing for a little while.  I think part of dilemma is just going through, color by color, has been rather boring for me.  Sometimes, what seems like a great idea at the beginning, sort of turns into a dud.  It’s all a part of a process.  So obviously I’ve continued writing, but about things more interesting to me than the colors used in a satellite imagery payload for pictures.

I will try to finish it, though, which is why I made that desperate reference to Coldplay in the title.  But just in case there are some pop-culturally illiterate people reading this, we’ll be talking about the color yellow for a little while, and figure out how DigitalGlobe may use it for their products.  I guess the answer is easy enough here.

Yellow is used for vegetation applications, at least that’s what DigitalGlobe say in this presentation (slide #16).  Also, they say it’s used to identify the “yellow-ness” (their word, not mine) of what’s being imaged.  So not much information there.  But FAS.org does have a pretty good posting on the whole “remote sensing” thing (which is synonymous for imagery satellites taking pictures) regarding the vegetation applications.  They don’t call out yellow specifically, but the upshot is the author advises using a little common sense with figuring out what colors help to identify what’s going on below.

That advice means, think about your experiences with yellow when you’ve interacted with plants.  Lawns, for example, when they go dormant turn a sort of brownish yellow.  Wheat turns brownish yellow or gold when ready for harvesting (I think).  Of course, unhealthy/underwatered plants turn yellow.  The examples go on.  So, maybe that’s what DigitalGlobe means about the “yellow-ness” of what they’re observing.

But they also mention yellow helps with the development of “True Color” for human vision.  According to the wiki, a true color picture is an image that’s rendered to look as natural as possible.  The way an object or landscape looks in an image would be the way it looked if the viewer saw the object or landscape in real life.  The Wikipedia article has a great few examples of true color vs. false color (true color image example is shown below), so go there if you’re interested in reading more about True Color.  Besides, according to Ms. Lauper, it comes shining through–and that’s why she loves you.

True Color image from wiki

Why is true color important?  It just makes it easier for the person viewing the image to understand what’s being depicted.  Why not use the same colors in a picture for the things we’re used to looking at in real life?  That actually makes sense, right?  And the less time you have to spend figuring out what colors mean, the more you can concentrate on what’s really important in the picture.

So there’s yellow for you.  Just watch out where the huskies go and don’t eat snow of that color.

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