Did you ever use a Photoshop feature on a regular basis—perhaps with the guidance of Deke in a book exercise or video? And although you get the results you want, you have no earthy idea why they’re working the way their working? Or maybe a slightly earthly idea, but much remains a mystery. Possibly this has happened to me with regard to the Levels command. So this week, comfy in the lounge, I dared to reveal my almost complete ignorance and asked Deke to introduce me personally to Photoshop Top 40, Feature #9, aka: the Levels command.

What are “levels” exactly? You find it under the Image > Adjustments menu in Photoshop, so you know it’s one of those global tonal adjustments. But what is it controlling? Well, luminance, yes. But luminance on a channel-by-channel basis. And what does that mean? And how can we harness that control to fix an image? Even those of you who already know what you want to do with levels will have a better idea of why you want do it after this conversation.

Here’s what you’ll learn from this week’s show:

• How to read the histogram in the Levels dialog box or adjustment panel pane.
• What those triangular sliders actually represent, including the mysterious grey (gamma) triangle in the middle. (Hint: it involves exponents.) 
• What those numerical values actually mean.
• How you can think of Levels as a “masterfully implemented Brightness/Contrast command.”
• How you can mentally compare the information in the histogram and image preview to figure out what the heck your Levels adjustments are doing.

And if you’d like to follow along, you can download the very file we’re experimenting with by right-clicking on the image below and choosing Download or Save (depending on your browser).

And all the while you get to hear Deke be his compassionate instructor-self, as tells me I’m exactly right when I naively parrot back exactly what he just said. You get to hear me ask just-intelligent-enough questions that you think I might be faking my ignorance or softballing the guru. (It’s my secret.) If you enjoy those times when I plaintively ask, “Why, Deke?” this is the show for you. And don’t worry, I protect you dear dekeOmaniacs, by telling Deke we’ll have to deal with the individual color channels in the Levels command in a later episode. My beginner’s brain can only take so much.

Where else can you have me ask questions you’re too embarrassed to ask? Here’s the regular-quality (128kbps) audio file. You can stream, or for best results, right-click and choose Download or Save. For you audiophiles out there, here’s the link to the high-quality (320kbps) version. Be sure to download, don’t stream. And don’t forget the usual suggestion to subscribe via iTunes.

Cheers to the Levels command and the microstock sites and photographers who find us sample images that let gurus like Deke deftly explain commands like Levels to rookies like me!