[tweetmeme]At all times no matter how good the picture is, you always have to do color correction.

Sometimes we have jobs where we have to do color correction of a large number of images in a short time for example; an article that has to be publish the next day.

In just 4 quick steps we can greatly improve an image.

Image Preview

Before we get started, let’s take a look at the image we’ll be correcting

Step 1 Curves

The first step will always be correct curves. Image> adjustments> curves

The most traditional way to correct the curve is S-shaped An S-curve adds contrast to the midtones at the expense of shadows and highlights. For doing it, it the upper part we make an anchor point and pull upward. At the bottom we make an anchor point and pull down.

Depending on the image we will pull more or less to get the desired brightness and contrast.

A tricky aspect is that even minor movement in an anchor point can result in major changes in the final image.  Abrupt changes easily induce posterization by stretching tones in regions with gradual tonal variation.  Therefore moderate adjustments, which produce smooth curves usually, work best.

Step 2 Color Balance

The following will correct the color balance.

Image > Adjustments > Color Balance

In this case the picture is a bit green so we will increase the red.

If the image were to red, we can correct the tones, lowering or raising red or green.

Step 3 Exposure

Now adjust the exposure of the photo, particularly the gamma. The Gamma slider works in a similar fashion to the Brightness slider in Adobe Camera Raw. Moving it to the right increases the mid-tone brightness of the image, while sliding it to the left will darken the overall appearance of the image.

Image > Adjustments > Exposure

Step 4 Unsharp Mask

An “unsharp mask” is actually used to sharpen an image, contrary to what its name might lead you to believe.  Sharpening can help you emphasize texture and detail, and is critical when post-processing most digital images.

Filter > Sharpen > Unsharp Mask

  • Amount is usually listed as a percentage, and controls the magnitude of each overshoot.
  • Radius controls the amount to blur the original for creating the mask, shown by “blurred copy”
  • Threshold sets the minimum brightness change that will be sharpened.  This is equivalent to clipping off the darkest non-black pixel levels in the unsharp mask.

The threshold setting can be used to sharpen more pronounced edges, while leaving more subtle edges untouched.  This is especially useful to avoid amplifying noise.

In a 300dpis image the average values are

  • Amount: 50%
  • Radius: 4
  • Threshold: 3

This must always be the last filter applied. If you want to apply another filter or effect you must do it before unsharp mask.

Below are images before and after retouching. This editing should not take you more than 5 minutes to do.

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Javier Cantero

Javier Cantero