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Layers and Layer Masks – Part 3

Non-destructive Image Editing in Photoshop

Layers & Layer Masks – Part 3


In Parts 1 & 2 the basic concept of Non-destructive Image Editing using Adjustment Layers and Layer Masks and some of the techniques involved were outlined. In this article we shall look at ways of using an Image Layer as a pseudo Adjustment Layer and Layer Masks on Image Layers.


Cloning Non-destructively

Cloning directly on the Image Layer is destructive in that the pixels in the original image are replaced with the pixels from the clone source. To clone non-destructively insert an empty layer above the Image Layer by making the Image Layer active by clicking on it and then clicking on the ‘Create a new layer’ icon at the bottom of the Layers Palette (Fig 1).


            Fig 1 Empty Layer

With the empty layer (Layer 1) active select the Clone Tool from the Tool Box and in the toolbar at the top of the Photoshop window check that the Mode is ‘Normal’, Opacity is 100% and from the Sample dropdown list select ‘Current and Below’. Recheck that Layer 1 is active and clone as required. The cloned pixels are placed on the empty layer and mask out the equivalent pixels on the Image Layer which is untouched. This may be confirmed  by turning off the Image Layer to reveal the cloned pixels on the empty layer.

If a mistake is made during cloning turn off the Image Layer by clicking on the ‘eye’ icon in the Layers Palette and use the Eraser tool to remove some or all of the cloned area revealed on Layer 1; turn the Image Layer back on, highlight (make active) the empty layer and clone again as required. In this technique the empty layer is used as a pseudo Adjustment Layer in that it contains the cloning information in just the same way as a Levels Adjustment Layer contains the tonal information applied to the Image Layer.

At times it is advantageous to clone at less than 100% opacity, e.g. to insert a little texture into burnt out areas in a sky where it is not possible to recover detail by other means. Set the opacity to, say, 5-10%, select a point in the sky as the clone source and clone into the highlight area to give a little texture. If the opacity setting is too low i.e. the texture cloned in is not sufficient, simply clone into the area a second time; if the opacity setting is too high, i.e. too much texture is cloned in either reduce the opacity of the clone layer or start over at reduced opacity.


Non-destructive Sharpening

Sharpening using Filter > Sharpen > Unsharp Mask/Smart Sharpen is a destructive process in that the sharpening effect is applied directly to the image and once applied cannot be adjusted. To sharpen non-destructively apply the sharpening to a duplicate image layer created by dragging the Image layer to the New Layer icon shown in Fig 1. This non-destructive method of sharpening has the added bonus that the degree of sharpening can be varied ‘after the event’ by either reducing the opacity of the layer and/or applying a layer mask and masking out certain areas fully or partially as shown in the following example of sharpening a portrait (Figs 2-4).



Fig 2  Unsharpened


Fig 3  Layers Palette



Fig 4  Eyes, Lips Sharpened


Fig 5  Sharpened Area


The unsharpened image is shown in Fig 2.

Drag the Image Layer to the New Layer icon to create a duplicate Image Layer which by default is named Back-ground Copy, but has been renamed Sharpen in this example for clarity. Sharpen the image by applying Unsharp Mask; the degree of sharpening can be reduced if necessary by reducing the Opacity of the Sharpen layer and if the sharpening is unsatisfactory the Sharpen layer can be dragged to the Trash Can and the sharpening process repeated. For most images global sharpening is quite satisfactory, but in some cases it is preferable to sharpen only parts of an image or to vary the degree of sharpening across the image. In the case of a portrait an overall sharpen will tend to reveal all the pores and imperfections in the subject’s skin – an undesirable situation, especially from the subject’s point of view! The areas requiring sharpening are the eyes, eyebrows and lips. Add a Layer Mask to the Sharpen Layer (Fig 3), click on it to ensure it is active and then fill it with black – Edit > Fill. This masks out the sharpening over the entire image; with the mask still active zoom in to the eyes on the image on the monitor and select the Brush Tool. Using a soft brush paint on the eyes and lips at 100% opacity to reveal the sharpening in those areas. Reduce the opacity to, say, 75-80% and paint on the eyebrows and – maybe surprisingly, the nostril(s). The result is shown in Fig 4 and if the underlying Image Layer – the Background Layer is turned off the sharpened areas are revealed (Fig 5). If the Sharpen layer is turned off completely the original image is revealed in it’s original unsharpened state – in other words the sharpening process outlined above is non-destructive.


Add a Layer Mask to an Image Background Layer

By default when an image is opened in Photoshop it appears in the Layers Palette as a Background Layer with limited properties – e.g. the layer cannot be moved within a stack of layers nor can a Layer Mask be added. To move or add a Layer Mask the Background Layer must first be converted to a Layer by double clicking on the layer which brings up the New Layer Dialogue box (Fig 6). By default the New Layer is Layer 0 – change this if you like, but leave all the other options at default and click on OK (Fig 7).




Fig 6 New Layer Dialogue Box.

Fig 7  Background Converted to Layer and Layer Mask added.

Clicking on the Add Layer Mask icon – inactive for Background Layers, adds a Layer Mask to the Image Layer. The occasions on which this action is necessary are rare, but the explanation is included for completeness. At least one Third Party sharpener, Photokit Sharpener, will only operate if a Background Layer is present and there may be other software programs with the same requirements. The most likely scenario in which the original Background Layer has been converted to a Layer is in the case of images based on multiple images. If the bottom layer in the stack is a Layer it can be converted to a Background Layer by making it active (click on it to highlight) and then Layer > New > Background from Layer.


And finally ….


Mixing Colour and Monochrome

You may have wondered how to produce an image in which the main subject matter is in colour and the background in monochrome.

Duplicate the original Image Layer by dragging it to the New Layer icon and add a Layer Mask by clicking on the Add Layer Mask icon. With the duplicate image active – the Background Copy add a monochrome conversion Adjustment Layer and clip it to the duplicate image layer as described in Part 2 of this series. In this example (Fig 8) a Black & White Adjustment Layer (CS3,CS4 only) has been added, but Channel Mixer or Gradient Map would be equally satisfactory in CS2 and below. Click on the Layer Mask and paint on the area on the screen image that you want to see in colour using black at 100%. The colour of the original image is revealed where the monochrome conversion is masked out on the Layer Mask (Fig 9)



Fig 8  Layers Palette for Fig 9

Fig 9 The Part Colour Image


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