Wednesday, March 4th, 2009

Sharpening in Lightroom 2

Sharpening is the last step in editing an image. If you’re working in Lightroom then you have a very sophisticated Sharpening tool at your disposal. It’s hard to determine what the coolest part of the process is – the Detail and Masking sliders or the fact that sharpening is applied to only the image luminosity so it doesn’t mess up the image colors.

To sharpen in Lightroom, open the Develop module and the Detail panel to show the sharpening tools. A good starting point for most images is to set the Amount to 100, set the Radius to 1.0 and the Detail to around 25. As an aside, it’s nice to see that Lightroom is realistic about the appropriate radius to use and it limits you to a value between 0 and 3 which takes some of the guess work away from determining what value you should use.

Now you have a starting point, adjust the Detail and Amount sliders to see how they affect the sharpening. To see the before and after, press the backslash (\) key. The Detail slider is unique to Lightroom – it doesn’t appear in Photoshop. What it does is to remove halos around the sharpened edges. Low values for Detail reduce halos and higher values allow them.

The Masking slider is a way cool tool. It lets you remove the sharpening from texture areas of the image and areas that you typically would not want to be oversharpened such as skin tones. To use it, drag the Masking slider to around 75 and compare the results. You should see less sharpening in areas that don’t typically need it the larger the Masking value. To see what the mask looks like, hold the Alt key (Option on the Mac) as you drag on the slider and you’ll see a grayscale mask in place of your image. The white areas of the mask are the areas that will be sharpened – they are the edges in the image – and the black areas are those that will not be sharpened or which will be sharpened with less intensity.

The mask gives you a lot of control over how the sharpening is applied to the image and it prompts the question “why isn’t this in Photoshop too?”

Helen Bradley

Wednesday, February 25th, 2009

Photoshop: Fixing photos shot from airplanes

One of the cool things about getting a window seat in an airplane is that you get a unique opportunity to photograph things from a high vantage point. On the flipside, when you get them home you often find photos taken from the air look washed out and the colour is poor. Luckily there is not much that Photoshop can’t recover provided the photographs are in focus. So if you scored a window seat lately and if you have images that fix, I’ll show you the Photoshop tools you need to fix them.

Understand the problems
Most airplane photos look washed out and they don’t have the richness of colour that you might expect them to have. The first step in fixing them is to boost the tonal range in the image using a levels adjustment – a by product of this is that the colour gets a boost.

Step 1
Start by making a duplicate of the background layer so that you’re working on a copy in case you need to refer to it later on. To do this, right click the background layer in the layers palette and choose Duplicate Layer.

Step 2
Select the background layer and choose Layer > New Adjustment Layer > Levels and click Ok. The Levels histogram tells you a lot about the state of your image. In most cases you’ll lack white whites and black blacks and most of the image content will be around the middle of the image. Drag the right and left sliders below the chart so that there are below the points where the chart data begins. This should give the image an immediate boost in contrast and some boost in colour too. Adjust the midtone slider if desired to fix the midtones in the image and click Ok to confirm your settings.

Step 3
Colour fixes: Often the image will contain too much blue and you can adjust this using a Curves adjustment. Choose Layer > New Adjustment Layer > Curves and click Ok to display the curves dialog. Click the Channel list and choose the Red channel. Drag up on the middle of the Red channel line to add some red to the image. Repeat with the Green channel adjusting it as required – drag down on the middle to remove green and up to add it. Finish with the Blue channel.

If you’re unsure which way to go with the adjustment, give the line a good pull in one direction or the other to see what happens, back off the adjustment to get something less intense. Different places on the curve line will give you different effects so experiment either side of the midline. Click Ok when you are done.

Step 4
Fixing uneven contrast: Photographs shot from high up are generally display better tonality in the areas closer to you and poor tonality in areas farther away. To fix this add another layer by choosing Layer > New Layer and click Ok. Fill this layer with a gradient by selecting the Gradient tool and select the Black to White gradient. Choose the Linear option and drag the gradient to fill the layer. You want black at the top of the layer and white at the bottom – if you get it wrong, drag in another direction till you get it right. Don’t worry that your photo has disappeared in the process!

From the Blend modes dropdown list choose Color Burn. This will darken the image considerably particularly in the areas where the black colour appears. Adjust the layer Opacity in the layer palette until you get an acceptable result.

Step 5
Final touches: To finish the colour fixing, boost the saturation using Layer > New Adjustment Layer > Hue/Saturation and increase the Saturation a little. If the image needs a little lightening and if you’re using Photoshop CS3 or CS4, use a Brightness/Contrast adjustment layer. If you’re using Photoshop CS2 or earlier, use a Curves adjustment and this time drag the composite RGB curve upwards to lighten the image. The Brightness/Contrast tool in earlier versions of Photoshop is to be avoided at all costs as it damages good pixels in the image – the new tool that first appeared in Photoshop CS3 is much different and much better.

step 6
Sharpening: The final step is to apply some sharpening to the image. To do this, you need a single image layer so press Ctrl + Alt + Shift + E to create a composite layer. Select this layer and use Filter > Sharpen > Unsharp Mask to sharpen the image. Set the Radius to between 0.5 and 1 and set the threshold to under 10. Adjust the Amount until you get a good sharpening of the image.

Helen Bradley

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