Isolated Colour Effect

Isolating a portion of an image in colour may be considered a little clichéd, but nevertheless is an effective way of enhancing the point of focus of an image.

In creating the effect, we will have a look at Photoshop’s Color Range command to make a selection, as well as using masks to fine-tune the selection.

Of course it always helps to work with great imagery! And the image used in this instance can be downloaded from Pexels, and a big ‘thank you’ to photographer Zigmars Berzins for making available on a Creative Commons license.

Making the initial selection

Choose Select > Color Range to open a dialog box.
Click on the red of the dress (the cursor will appear as an eyedropper) and notice how this selection appears in the dialog.

You can shift-click either on the image or within the dialog box preview area to add to the initial selection until the dress appears white (or almost white) in the dialog box.

Use the Fuzziness slider to expand the selection if necessary. When satisfied that a useful selection has been made, click OK to exit the dialog box.

Using Black & White Adjustment

Once the Color Range dialog box is closed, the selection appears as ‘marching ants’ on the canvas.
Choose Black & White… from the adjustment layer menu at the bottom of the Layers panel. 

The colour will be removed from the dress, but the background remains in colour.
Note the mask thumbnail on the adjustment layer – white on the mask indicates the portion of the canvas with the Black & White adjustment is impacting.
With the mask thumbnail selected (white braces at the corners of the thumbnail), press the Invert button in the Properties panel; or choose Image > Adjustments > Invert.

Cleaning the mask

Ensure that the adjustment layer mask is selected.
When a mask is selected, the foreground & background colours (in the Tools panel) should default to black and white.

Paint using a white brush to paint out any unwanted colour which still appears in the background.
Conversely, paint using a black brush to paint in any portion of the dress which does not appear in colour.
Note – the following keyboard shortcuts may prove useful…
‘x’ toggles foreground/background colours
‘[’ reduces brush size
‘]’ increases brush size  

Editing Black & White Adjustment

Once the adjustment layer icon is selected, the Properties panel (Window > Properties) displays sliders which effect the tonality of the greyscale effect.
As this image has a lot of vegetation, adjusting the Greens will impact the lightness/darkness of the background. 

Changing the dress colour

With the Black & White adjustment layer active, choose Hue/Saturation from the Adjustment Layer menu at the bottom of the Layers panel.
This puts the Hue/Saturation adjustment at the top of the layer stack.

Move the Hue slider to change the colour of the image (since only the dress appears in colour, it is area impacted by the adjustment).
Change the blend mode for the Hue/Saturation adjustment layer from Normal to Color – this ensures that the tonality of the underlying image shows through the new colour.
Note – moving the Lightness slider will impact the greyscale background as well as the dress. If you wish to ensure only the dress is impacted: Alt+drag the mask from the Black & White layer to the Hue/Saturation layer (this duplicates the mask); then invert this mask by pressing Ctrl/Cmd+i or by choosing Image > Adjustments > Invert.