A Photoshop Tutorial – Levels

My friend Kenneth of Investor Blogger and Obblogatory recently requested some basic Photoshop tutorials. Perhaps the best place to start is with a tutorial on Levels. Make sure you click on the images for a larger version – the small ones don’t fully show the details and color.

For most people, the main objective after the picture has been taken is to either have it look good for posting on Flickr or sending as email, or to make an inkjet print at home, or a print at a photolab. The first thing you need to do is to adjust the tonal range so that the photo has a good, full contrast. In general, the biggest concern will be how light or dark the photo is – are the blacks black and the whites white? And for that, we can look at Levels in Photoshop. So lets start with an image that needs some adjustment.

[singlepic id=153 w=500]

We can see that this shot is a little underexposed and lacks contrast. If we look at the histogram display, we see that all the values are over towards the left. The histogram is a graph that displays the tonal levels from dark (black) on the left to light (white) on the right. The graph will look different for every different photo – there’s no such thing as an ideal, one-size-fits-all histogram. In general though, we want to see our graph spaced over the entire histogram, not bunched to the left like the following screenshot.

[singlepic id=154 w=500]

To fix things, we want to go to our Layers palette (F7) and create a Levels adjustment layer, as shown below. We can make the same adjustments directly onto the image without using Layers, but this is destructive – we permanently change the pixels. Using Layers means that we can non-destructively adjust the image without permanently changing pixels. This allows us to revisit the image in the future and make further adjustments as we desire without degrading the image. Non-destructive editing is always a better choice than destructive editing – it’s one of the reasons why we shoot RAW instead of jpg, assuming our camera is capable of it.

[singlepic id=156 w=500]

This will bring up the Levels dialog. To improve the tonal range, we want to use the highlight slider (shown below) and drag it to the left. For finer control, hold down the option/alt (Mac/PC) key while you click on the slider to see exactly where the highlights pop out.

[singlepic id=158 w=500]

You want to drag it closer to where the tonal values are on the histogram.

[singlepic id=159 w=500]

And now do the same with the shadow slider, located on the left. Again, you can hold down Option/Alt for finer control.

[singlepic id=160 w=500]

Once things look good, click ok in the Levels dialog. Notice the difference in both the image and the resulting histogram.

[singlepic id=155 w=500]

You can now save the file as a TIFF or PSD which allows you to preserve the layer structure. As mentioned above, this lets us revisit the file in the future. To make changes it’s simply a matter of double-clicking the adjustment layer icon in the Levels layer.

[singlepic id=157 w=500]

To save it as a jpg for print or the web, simply flatten or merge the layers (Cmd/Ctrl-Shift-E) or choose the option from the Layer menu at the top of the screen.

And there we have it – our finished image. Or, our image that’s ready for any further editing we wish to do.

[singlepic id=152 w=500]

This entry was posted on Tuesday, February 17th, 2009 at 13:30. It is filed under Learn and tagged with Photoshop, tutorial. You can follow any responses to this entry through the RSS 2.0 feed.