The Color Purple and the Digital Camera

By now most of you have caught on that this isn’t a technical photography blog, but that I’m not above putting out a little know-how if I think it could be useful.  With wildflower season approaching, I think you flower shooters will like this one – purple flowers looking blue and how to fix it!  This drives me crazy and I’ve actually gotten into arguments with people about it, with them usually insisting the flower actually was blue.  Uh, no folks it wasn’t – they’re called violets, not blues ok?  That’s a different topic though – what we’re going to tackle now is a wicked easy way to color correct your flower pictures.

Now, without getting all techy on you a hell of a lot goes into managing color in digital photography and I’m not going to get all preachy about it.  Let’s assume you have calibrated your monitor to the best of your ability.  Let’s take it as read that you’ve selected the proper white balance when you were shooting.  Still have blue flowers?  It’s not your fault.  It’s the sensor.  In a nutshell, digital sensors have a difficult time seeing, rendering and processing purple and often put out pure blue instead.  If you want the techy reasons Google is your friend and there is no shortage of articles about it.  Even film had trouble reproducing purple accurately.  Mostly it has to do with the color purple itself being made up of red and blue, two colors on opposite ends of the color spectrum and digital sensors, even very modern ones, have trouble.  It’s been a thorn in our collective sides for years.  A quick Google search pulls up a ton of people asking why their purple flowers look blue.

I find it’s most obvious when shooting in the shade, which, let’s face it, is where a lot of us prefer to shoot wildflowers.  Harsh sunlight is not our friend.  Shots in sunlight are more accurate, but often can be a bit off, too.  Some people also report that using an IR or UV filter makes the problem more extreme, so if you’re using one on your camera, remove it when photographing purple wildflowers.

I’m going to use this shot of chicory to illustrate my process.  I was shooting in the shade of a tree on a sunny day, I have made some changes like contrast, sharpening and cropping and kept those all the same, only varying the adjustment I want to highlight in each example.  Here’s the starting shot –

A lot of people will tell you that all you need to do is adjust your white balance and you’ll be all set.  Well, yes and no. If your purple flower is basically purple, just a little cool, changing the WB will probably work a treat.  If your flower looks really blue like the shot up there, adjusting ONLY white balance may get to a color approaching what you saw in your purple flower, but it won’t be exact.   And just look what it does to the rest of the shot –

The quick and easy fix for this lies in your HSL panel (I’m using Lightroom, but many other robust editors also have this functionality, you just need to find it). Each color has a control with the cool end of the the range to the left and warm to the right.  To make blue purple we need to increase the amount of red which means sliding to the right (warm). How far you drag your slider depends on how off your color is.  You could also use the targeted selection tool (that little bullseye under Hue) and put your mouse right on the blue color and then use the arrow keys to make the adjustment, but it’s not necessary for most shots where the color you want to change is clearly differentiated.

Here’s the finished shot with the color dialed in as close as I can come to what it was IRL (and I kept the flower handy to compare which is great if you can do it). Remember, all other factors are equal; overall saturation, white balance, sharpening, contrast, all of it the same.  Only the color slider is changed –

You eagle-eyed folks will have spotted some chromatic aberration where the purple and the green meet.  I’ve found this occurs fairly often with this combination even with lenses that don’t throw color aberration at any other time.  Yep, there’s a wicked techy explanation for it, but I won’t give it to you here (Google is your friend if you want to know why).  Using LR 3 I could probably correct this, but Adobe in their wisdom decided to make this correction tied to lens profiles only in LR 4 and they can’t be bothered to include a single piece of Olympus hardware in their application.  Thanks guys.  I love being given short shrift.  But anyway, you folks with mainstream cameras can probably fix this easily.

Here’s one more comparo for you and it really shows why they’re called Violets and not Blues (and how even in bright sun digital sensors can be confused by purple). All  I did was adjust the hue and luminance values with the blue and purple sliders and although that makes it seem like I adjusted the green channel, I didn’t.  Scout’s Honor.

That wasn’t so bad, was it?  Easy peasy.  Use the technique with that other bane of the digital sensor – magenta and dark pink.  It never looks right out of the camera and it’s always HSL panel to the rescue!