House of a Different Color, part 2


We left off our home improvement project with cobalt blue dahlias and a ruby red driveway. What else can we do but paint the house green?

Here’s the house of someone who is planning to re-paint.

It’s not a great photo, just above camera phone quality, but that’s OK. I can relax and not feel like I have to treat each pixel as though it were my last. The folks who own this house picked some swatches at the paint store and gave them to me, along with the photo.

With the swatches, I could either scan them or try to swipe them from the paint manufacturer’s website. I originally tried the scanning method, figuring that, properly tagged with a profile, the scan should be fairly accurate. It wasn’t. I think my scanner needs to be calibrated, but since I don’t feel like going through that procedure right now, I went to the website and swiped the swatches. The site uses Flash, so I had to do a screen grab to capture the swatches. I opened them up in Photoshop and checked the LAB values.

Ah, LAB color. Telling someone you prefer to work in LAB is like saying you do your taxes with an abacus. Usually they’ll say, “Oh…” and then start talking about something else. LAB can be a real conversation ender. If you were dating another publishing geek, it might be grounds for a break-up.

“I’m sorry, it’s not you, it’s your colorspace.”

Actually, LAB is easy to use once you get the hang of it. The numbers are more intuitive to me than RGB ones. Coming from a prepress world, I still can’t look at RGB numbers and tell you what basic color they represent, like I can for CMYK and LAB. The thing I like most about LAB is that it breaks the lightness value completely away from the color value. Unlike CMYK, where the fickle nature of the black channel means several different sets of numbers can equal the same color, each LAB value is a unique and unambiguous (and some times imaginary) color. Note to self: do some posts on the fundamentals of LAB in the future.

I became a fan of colorizing with LAB after reading Dan Margulis’ book Photoshop LAB Color. Well, “read” is too strong of a word. I attempted to read it, like my son attempts to read the newspaper. He’s 8, so some of the news sails right over his head (thank goodness). I’m the same way when it comes to reading Dan Margulis books. I know there’s really deep stuff there, but it’s often so dense (or maybe I am) that I have a hard time reaching it. I sometimes have to read the same sentence two or three times to really get it. It’s Photoshop as a foreign language and my accent isn’t totally there yet. I’ve taken a few classes by Dan at conferences, and he seems like a decent guy. But he scares the hell out of me in print.

I can still cut myself some slack, though. I first started using Photoshop in 1995, so that makes me a Photoshop teenager. Not old enough to drive or vote in Photoshopland, but I’ve learned a thing or two. I started using LAB only three years ago, so I’m just a LAB toddler. I can walk and talk but occasionally fall down and drool all over myself. Mostly I just have fun playing.

Here’s the first swatch I was asked to try out on the house. It’s called Moss.

More like Dead Moss. The moss that grows on my lawn is a tauntingly vibrant green. Ten times greener than the grass. I couldn’t make it look this dead with a 50 gallon drum of Round-Up and blow torch. Maybe this is fossilized moss. Mossil?

Anyhow, it might be a nice color for this house, so let’s put it on.

The game plan is to drag the Moss swatch into the Photoshop file containing the image of the house, then add an adjustment layer over the house to mimic the color of the swatch. Margulis’s tool of choice is Curves, but if you’re playing along at home, I think you can get useful results from any one of several tools, even our pal Hue/Saturation that we used on the dahlias. So choose your weapon.

But here comes the hard part. You knew there was a hard part coming, didn’t you? The hard part is picking the right spot on the house to match to the swatch. You don’t want anything in the shadows. Nor do you want anything totally washed in sunlight. Ideally the photo would be taken around noon on a day with uniformly neutral gray, but not too-thick cloud cover. The kind of light you find in a MacBeth booth. Since the odds of this are zilch, and there isn’t a MacBeth booth big enough to jam a house into, we may have to hunt and peck around till we get the sweet spot of most “average” lighting.

Our photo was taken on the exact wrong kind of day for our purposes, perfectly clear with the sun casting strong shadows over most of the house. You’ve heard of “Luck of the Irish?” Well I have “Luck of the Scottish.” Let’s leave it at that. That cats with lightsabers job might have been easier. But, no guts, no glory. Take your best guess and drop a color sampler on it. That’s why we’re working on an adjustment layer. Just make sure you have something in the range of a 5 x 5 sample size selected.

Anyway, if I do a crummy job, I can always offer the home owners some free graph paper as a consolation prize.

To proceed, either stick a color sampler on the paint swatch or write down the numbers on a scrap paper or whatever you have handy.

Next, stick a sampler in your best guess of neutral lighting. Then play with your adjustment layer controls till that spot matches the swatch.

That’s it. You’ve perfectly simulated painting the house with Moss. Nothing to do zoom out and admire your craft.

Send it on to the homeowners, who will no doubt reward you with praise and/or beer and salty snacks.

Yup, that’s it……..

OK, there is the slight matter of the entire picture looking like hell. Don’t worry, we can fix it.

To select or extract just the walls of the house away from the tree branches, shrubs, car, trim, and roof is going to he one nasty job. I am far too lazy for that. Especially when I can flip one switch and have Photoshop pretty much do it for me. You’ll find that switch by double-clicking (remember the joys of double-clicking???) on the layer thumbnail to reveal the Layer Style dialog.

This is where our choice to work in LAB is really going to pay off and the person who dumped you for that RGB hotshot is going to come crawling back. The Blend If controls are going to act like Moss-B-Gone. Switch from Lightness to the B channel, and start dragging the slider on the blue end to the middle.

This hides everything that is more blue than yellow from Mossification.

Remember that extra copy of the background layer we created at the start of this job? Turn it on and let the original sky, car, roof, pine trees, and grass show through.

The taillight and some of the grass and mulch is still bad, so a quick and sloppy job with the brush tool to paint some black over those areas on the adjustment layer’s mask will finish the job.

From here, you can paint the house any other color by duplicating the adjustment layer and tweaking the values therein. And while you’re at it, water the grass (or moss), will ya?

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One Response

  1. The bright green tail light at the intermediate step is hilarious!

    So I would have used “Replace Color” to paint the house walls, and ended up with the wall in shadow looking equal to the wall in sunlight. Your approach looks a lot better.

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