The Gradient Tool

The Gradient Tool is found in the tools pallet. It is used to paint a band of colours onto an image. The band of colours is selected in the Gradient Editor which is described in another note.

Figure 1 above, shows the tool bar that pops up when the gradient tool is selected. It consists of a reset option that restores the defaults, a band showing the current colours, five options for how the colours are painted, a drop down box to choose a blending mode, a choice of opacity, a reverse option, a dither option and a transparency option. The operation of these selections is described below in the order that they appear in figure 1.

Reset

Click on the reset icon to reset the default conditions.

Current colours and Edit

Clicking on the band of colours or on the Edit button will bring up the Gradient Editor. This is described in a separate note. Clicking on the small arrow at the side of the band will also bring up a small selection of gradients.

Painting Modes

Figure 2 below shows examples of using the five different modes of painting the colours. Each mode is used by dragging a line across the image. The small white box around the Default mode, in Figure 1 above, shows that it is selected.

The default produces a band of colours in this case from blue to yellow through red. The colours change from the start of the line to the end and the end colours are used to “fill in” any excess.

With the circle, a straight line dragged across the image will produce a continuous series of coloured circles with their centres at the start point of the dragged line. The length of the line defines the radius of the circle and beyond this the last colour is used to fill in.

For the sweep round, the line merely defines a direction and the colours sweep around the start point, as if being left by the hand of a clock.

The mirror image is similar to the default but it produces a second set of colours reflected about the start point.

The squares mode is similar to the circle except that squares are formed rather than circles.

Try experimenting it will be a lot more informative than my explanations.

Blending mode

It is possible to blend the painting with the underlying image. The effects are the same as those between layers.

Opacity

As with any painting tool the opacity can be changed. The level of opacity chosen affects all of the colours as they are painted. It should not be confused with the transparency (see below).

Reverse

Reverse simply reverses the colours. So a red to green band would be changed to a green to red band.

Dither

Dither mimics intermediate colours by introducing either random or patterned groups of colours to approximate intermediate colours.

If you want to see the effect of dither then make the foreground colour close to a mid grey say Red =134 Green = 134 blue =139. Make the background colour say Red=130, Green=125, Blue=125. Toggle the dither on by clicking on its tick box until a green tick appears. Use the gradient tool with the default gradient using the foreground and background colours (see gradient editor) to paint a gradient on blank file. In the layers pallet select a Hue Saturation Lightness adjustment layer and set the saturation to 100%.

Repeat the process with the dither turned off and compare the two results.

The top of this picture is with no dither and the bottom is with dither turned on.

The reason for the patterns is that near grey there are very few hues available. When they are saturated this becomes obvious. With no dither the red and yellow in this example compete for dominance giving bands of colour. With dither on the result is a smoother transition but a much grainier picture.

Transparency

In the gradient editor it is possible to alter the transparency, or its opposite opacity, of different parts of the band of colours. The tick box labelled transparency turns the transparent mode on and off. If the box is ticked then the transparent parts will have the predetermined transparency, so the image underneath will show through. If the box is not ticked then the transparent parts will appear coloured. (Note that with the Gradient Map adjustment layer, transparency is not supported at all.)

Some Uses for the Gradient Tool

As with all tools there is an unending list of uses for the gradient tool here are just four.

The default gradient can be used to produce a graded colour from sky blue to almost white for adding colour to a grey sky.

The circle and square effects can be used to create a vignette by applying a white to black circle or square to the layer mask of an adjustment layer that darkens the image.

A default gradient on a layer mask can be used to lighten or darken progressively across an image.

Two images can be blended together by grouping one image with a clipping layer. (If you have a full version of Photoshop you can use a layer mask.)