0 Replies Latest reply on Feb 20, 2004 6:23 AM by (Phos±four_dots)

    Controlling Contrast - A Quick Tutorial by Mathias Vejerslev

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      Controlling Contrast - A Quick Tutorial


      Originally posted by Mathias Vejerslev - 03:27pm Jan 29, 2004 Pacific

      Managing the contrast in a photograph must be one of the most important tasks in post processing. These are just a few quick tips for the workflow of contrast enhancements.

      At minimum, Levels or Curves or perhaps both, are applied. We should get used to use Adjustment Layers instead of 'hard-copy' adjustments.

      A quick way of determining shadow and highlight burnouts in the Levels dialog is to Alt-drag the Levels end point sliders. The preview will clearly show when burnouts or blow-outs appear, even in which color.

      Users of Curves should be alerted that the Curves interface can be enlarged via a small icon in the lower right of the Curves interface. This allows more precise control when applying curve points.

      You can identify and define your shade on the curve directly in the image (one click in the image to preview, one ctrl-click to apply point to curve), then you can use the arrow keys to tweak the curve point, shift-arrow for 10x movement. The arrow keys can be used for many of Photoshop dialog screens with much efficiency and accuracy, although not all filters are equally optimized for them.

      One of Photoshops few features that I never personally use is the Brightness/Contrast adjustment. Many professionals agree that there are smarter way of controlling these
      factors than a pure linear approach.

      Here are two techniques broadly used amongst photo professionals, these are 'the old school of contrast':

      1) Increasing contrast with USM

      Duplicate layer
      Settings for web sized image: 1-20, 50, 0
      Settings for larger photos: 1-20, 70, 0

      Adjust duplicate layer blending to your liking

      I call this method 'Contrast Coating'. It can create a subtle contrast enhancement such as you know from very expensive camera lenses.

      2) Decreasing contrast with Contrast Masking

      Duplicate layer

      Set Image blend mode: Overlay or Soft Light

      Filter>Blur>Gaussian Blur:
      You can either choose a very low blur or a very large blur (0.3 or 30+ radius), if you choose a low blur radius, then you must decrease the layer opacity to a very low level (Which is what I did in the example below). If you choose a large radius, you must control the halo effect to a minimum.
      Contrast Masking can even be used as a 'fill flash' effect to rescue over-contrasty or backlit photos.

      {Below is an animated GIF] of these two effects, when aggressively applied to a neutral image of a domestic animal:

      I should note that there are effects to the colors of the image with both methods, but I had to restrict my palette to 256 shades to use an animated GIF, and the effect is better experienced first hand.
      In both of these recipes, you are left with a layer that you can blend and mask any way you like, so you can easily combine the two effects in an image, say to lift shadows, but increase highlight/midtone contrast if you like.