5.3  Colour to Mono using Gradient Map

One of the least known methods of converting a colour image to monochrome is using Gradient Map. Gradient Map uses an editable gradient to map a colour image in greyscale according to the tonal range of the image and is superior in use to greyscale conversion in that the RGB Channels are retained. In this example we shall use one of the standard black to white gradients provided with Photoshop^® to convert the same colour image used in the demonstration of the Channel Mixer method to monochrome.

Applying a Gradient Map Adjustment Layer brings up the dialogue box shown in Fig 5.3.1. Clicking on the drop down arrow to the right of the gradient shown opens up the gradient selection box containing the default gradients.

Fig 5.3.1 Gradient Map Dialogue Box (left) showing Gradient Selection Palette (right)

Select the third black to white gradient as it is the default black to white gradient and is not affected by the current selection of foreground and background colours in the Tools Palette, as shown in Fig 5.3.1.

Stage 1 : A Gradient Map Adjustment Layer is applied to the Image using the default black to white gradient.  

Fig 5.3.2  Gradient Map Adjustment Layer applied to image

Stage 2 : A Levels Adjustment Layer is applied to the Image and adjustments made for the Sky. The Layer Mask is filled with black. Selective painting back with white reveals only the effect on the Sky.  

Fig 5.3.3  Levels Adjustment Layer applied to Sky

Stage 3 :

A Levels Adjustment Layer is applied selectively to the Foreground by ‘Ctrl clicking’ on the Layer Mask of Levels 1 to select the Sky, inverting the selection and selecting Levels from the Adjustment Layer Palette. Adjustments are then made for the Foreground.

Fig 5.3.4  Levels Adjustment Layers applied selectively to Sky and Foreground