Selective Correction

Global corrections (i.e., those which affect the entire image) usually belong to the initial processing steps, while later fine-tuning often requires us to make local or selective corrections to certain tonal values, colors, or forms within an image. These types of corrections are equivalent to the adjustments made using masks, dodging, or burning in a traditional darkroom.

The spatial limitations of such corrections can be selected manually or by using explicit and implicit masks for:

► Geometric shapes (with or without transitions)

► Specific areas of color, brightness, or saturation

► Pixel masks made with brush tools and techniques

* See section 7.16, page 282 on this ► Control points (a la Viveza)*

technique. These selections can be adjusted later if you are working non-destructively, as described above.

Photoshop still uses its versatile selection tools and layer masks to edit selectively, but creating masks can be a complex (and destructive) process. Photoshop masks are also difficult to alter once they have been created.

Nikon Capture NX [47] introduced the new U-Point control point selection technique. This process allows very selective editing, but it is difficult to judge accurately - which is why Capture NX still includes traditional masking tools such as brushes and gradients. Nik Software [75] also offers U-Point technology as a plug-in (called Viveza) for Photoshop and Lightroom.

LightZone [46] uses geometric techniques to select so-called Regions within an image. These are easy to edit, and the precise image areas they affect are easily identifiable.

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