ZELDADZ: Post-Processing: Intro to RGB Curves

I'm definitely not one of those elitists who believes that photoshop is ruining the true art of photography. The opportunities we have for digital photo manipulation in this day and age are really cool. Enhancing highlights, shadows, and colors using the RGB curves tool is one of my favorite ways to post-process photos, and now I'll show you how to do it too!

I won't say post-processing (editing) is completely necessary, but it can do a great deal for an image. I totally admire those among us who can get exactly the shot they have in mind with nothing but their camera, but depending on what equipment is available and what style you're going for, oftentimes that's just not the case for most of us. And although some consider any form of edited photos "fake," I think there's no shame in enhancing your images to make them look the style you want them to. (I like to think of it like makeup- it enhances features, but its not like it makes my face fake unless it's completely overdone!)

**Now, I will take a minute to say that editing is not the solution to most problems. It's still extremely important to know your camera well and get the settings as right as possible while shooting. Editing can make good pictures better, but it doesn't do much for bad ones.**

For this tutorial, I'll be using GIMP, which you can download here, but numerous other programs also have this tool such as photoshop and Lightroom, as well as the iPhone app MagicHour.

First, open your photo editing program and open a photo in it. I'll be using one I took of some tomatoes at a farmers' market. Next, click Colors and select Curves from the drop down menu, as shown in the image above.

Then, this great little curves widget will pop up. (I minimized the other toolboxes to have more space for these on my desktop).

Pay attention to this widget as well as what the adjustments do to the photo.

It will open by default to the value channel, where you can control highlights and shadows. There will be a diagonal line in the middle of the box. Drag it down, like above, to darken your photo.

Or, drag it up to lighten it.

But you can also make more than one curve. If you want to add contrast, darken your shadows and brighten your highlights, like above.

Or, you can reduce contrast by brightening the shadows and darkening the highlights.

Another thing I like to do is to brighten the darkest shadows and tone down the brightest highlights but keep the contrast in between, which can be seen in the above curve.

You can also adjust amounts of different colors. Click the channel button in the curves widget to select another channel. I'll be using red here, but all the color channels work the same way.

Drag the line up to add more red to the photo. This change can be as subtle (above) or as drastic (below) as you'd like.

Drag down to add more cyan (the opposite of red) to the photo. The other channels are like this too:

Green controls both green and purple
Blue controls both blue and yellow

Similarly to the value channel, you can make the dark spots more red and the light spots more cyan (above), or vice versa (below), by making an s-shaped curve.

Above is my final image. I darkened the brightest highlights and lightened the shadows a bit, made the darker parts more red and green, and the lighter areas cyan and purple. I left the blue channel alone.