Image adjustments in Impasto

Adjustments change the colors and tones of the current layer. They live in the Adjustments menu: in the menu bar, or behind the Adjustments button in the title bar when Impasto uses a header bar instead of a menu bar. An adjustment affects the current layer only, and if a selection is active it only changes the selected area.

How adjustments work

Adjustments whose name ends in “…” open a dialog. While the dialog is open the canvas shows a live preview of the result, updated as you change the settings. Click OK to apply it or Cancel to leave the layer as it was. A progress window titled “Rendering Effect” appears while a slow adjustment finishes, and you can cancel it there.

Adjustments without “…” (Auto Level, Black and White, Invert Colors) apply straight away.

An applied adjustment is not burned into the layer’s pixels. It is added to the layer as an editable node, shown as a row marked Fx under the layer in the Layers pad. Right-click that row to:

• Effect Settings…: reopen the adjustment’s dialog and change its values. The layer re-renders with the new values.
• Blend Mode and Strength: choose how the result is mixed back into the image, and how much of it is applied. At a strength of 0 the layer looks as it did before.
• Rasterize: bake the layer’s effects and objects into its pixels, after which they stop being editable.
• Delete: remove the adjustment.

You can also drag the row to reorder it among the layer’s other nodes and objects. See Layers and objects for more on nodes.

Saving as an Impasto project (.ora) keeps the nodes and their settings, so you can still change them after reopening the file. Other formats save the finished pixels. See File formats.

Keyboard shortcuts

On macOS, Cmd takes the place of Ctrl. Every shortcut can be changed on the Adjustments tab of the Keyboard Shortcuts dialog; see Keyboard shortcuts.

The adjustments

Auto Level

Stretches the layer’s tonal range automatically, the same correction the Auto button in Levels makes. It has no settings.

Black and White

Removes all color, leaving a grayscale image. It has no settings.

Brightness / Contrast

Curves

Remaps tones by reshaping a transfer curve.

• Transfer Map chooses what the curve controls: Luminosity (overall brightness) or RGB (the color channels).
• In RGB mode, the Red, Green and Blue checkboxes pick which channels you are editing.
• Click on the curve to add a control point, and drag a point to move it. Right-click a point to remove it.
• Reset returns the curve to a straight line.

Hue / Saturation

Invert Colors

Replaces every color with its opposite, like a photographic negative. It has no settings.

Levels

The Levels Adjustment dialog sets the black point, white point and midtones.

• Input Histogram and Output Histogram show the tone distribution before and after the adjustment.
• Input sets the input values that become black and white.
• Output sets the darkest and lightest output values and the gamma (midtone) value.
• The Red, Green and Blue checkboxes choose which channels the changes apply to.
• Auto picks levels from the image, and Reset restores the defaults.

Posterize

Reduces the number of tones in each color channel, giving flat bands of color.

With Linked checked, moving one channel moves all three together.

Sepia

Converts the image to warm brown tones, like an old photograph.

Adjustments from add-ins

Adjustments installed by add-ins appear in an Add-ins submenu of the Adjustments menu. See Add-ins.