Adjust colors in images

Designers often need to adjust colors for many different reasons for many different styles of image. This series of How-to topics provides examples how the AliasStudio color adjustment tools operate.

The Color Balance, Brightness & Contrast, Saturation & Value, and Color Replace commands change colors or tonal values in a variety of ways. They provide quick and simple techniques to allow global or local color adjustments to an image layer.

Once, the designer was forced to use third-party applications for all color adjustments. The process of copying layer information between applications was tedious and error prone due to the lack of alpha channel support on the windows clipboard. This work can now be accomplished within AliasStudio.

The color adjustment tools in AliasStudio are aimed at designers who sketch, paint, render, or require fundamental photograph manipulation tools.

Balance color

The color balance tool enables you to adjust the amount of different hues in an image by choosing between thumbnails of color alternatives (red, magenta, blue, cyan, green, yellow).

The AliasStudio Color Balance window is not the same as Photoshop's Variations window, which adds and subtracts color based on the HSV color wheel that can cause undesirable color clipping problems. AliasStudio uses a more complex algorithm that improves hue shift while maintaining the integrity of the image.

Original Image

The Color Balance Window

This window is split into two horizontal regions: the preview area and the control area.

By default, this tool modifies the color of all the pixels in the active layer unless a global or local mask provides protection. The amount of color added can be adjusted using the Adjustment Type options, Color Balance Factor value and the number of clicks made on the sample hue thumbnails.

Preview Area

The preview region shows the original image and the current adjustment values that will be applied to the active layer. This technique allows you to see exactly what color changes will be made without the need to remember how the image looked prior to color adjustment. This window region also allows you to zoom and pan into the area of interest; all preview icons update to show the current viewing area.

Adjustment Area

Adjustment Type:

Select what to adjust in the image:

All Color Tones, Shadows, Midtones, or Highlights to indicate whether you want to adjust the dark, middle, or light areas.

Add hue to Gray Scale Areas

This option allows you to only color balance areas of the image with color and will exclude gray (white>black) areas of the image. When turned on, the color adds hue to the complete image.

Color Balance Factor:

Drag the Color Balance Factor slider to determine the amount of each adjustment.

Move the slider to the left to reduce, to the right to increase the amount of color that will be added.

Adjust the Color Thumbnails:

To add a color to the image, click the appropriate color thumbnail. Once clicked, the adjustment value is applied to the preview image on the left and the adjustment thumbnails update to display the next possible color selection. You may repeat this process any number of times, or click Clear at the bottom of the window to restore the original image.

Adjust colors

Import the image (File > Import > Canvas image

) or pick the layer to be adjusted in the Canvas Layer Editor.

Choose Paint Edit > Color correction > Color balance

. The active layer is loaded into the Color Balance window.

In this example we want to add blue to the image - that is, convert the bright rust color to a pure blue color.

First we change the Color Balance Slider to 100%. This shifts all hues to pure color but maintains the current saturation and value (shading range). Note how the thumbnail icons change to preview the possible color balance changes when you click the thumbnail.

Click the More Blue thumbnail and watch the preview window update to the current adjustment value as shown below.

Now click the More Cyan thumbnail and watch the preview window update to the current adjustment value. Also note the rear orange indicator light has changed because no mask layer or selection mask was used.

The hue looks very strong, so click Clear at the bottom of the window to restore the original image.

Adjust the color balance amount to 50% and click on the More Cyan thumbnail. This now adds 50% cyan to the original image. If you click the thumbnail again, it will add more cyan to the current selection.

The color balance window encourages experimentation with color balance, so play and have fun: when you are pleased with the preview, click Accept and the current adjustment values are applied to the active image layer.

Original Sketch

Quick Color Balance modifications of the same sketch

Protect part of an image from color adjustment changes

You can protect an image layer from any color adjustment by using a painted mask layer, a selection tool (marquee or magic wand), or a mask shape. This example uses a mask shape layer.

Choose any curve creation tool. In the paint panel choose Auto-Shape > Type > Mask.

Create the curve around the rear indicator. Note as you draw the curve, a mask is automatically created. In this example we change the layer mask color to blue using the Construction Plane Editor's Canvas > Canvas General Info window.

The rear indicator area is now protected from any color changes.

Choose Paint Edit > Color correction > Color balance

. Adjust the Color Balance Factor to 50% and click any of the thumbnails to adjust the color balance.

Notice how the rear indicator color has not changed because it was protected by the shape mask layer.

Modify gray scale regions of an image

Sometimes you want to add color to the gray regions of an image. First, load the image to modify. By default Add Hue to Gray Scale option is off.

Turn on Add Hue to Gray Scale and adjust the color balance factor.

Click the thumbnail icons to adjust the color balance. In this example we have added small amounts of red and yellow to the overall image (except the rear indicator, which was protected with a shape mask layer).

Although the effect is good, the alloy wheels have been tinted. Cancel the operation, and create another shape mask layer to protect the wheels and tires. Tint the car again.

Modify color saturation and value in an image

This tool allows you to adjust the tonal range of an image by providing sliders for saturation and value. It also lets you compare the original image with a preview image showing the modifications as you change the slider values.

Example Workflow

Import the image (File > Import > Canvas image

) or pick the layer to be adjusted in the Canvas Layer Editor.

Choose Paint Edit > Color correction > Saturation & value

. The active layer is loaded into the Saturation/Value window.

Decide what tonal value to change. In this example, we'll increase the saturation of all the colors in the image to make the sketch more dramatic, and then decrease the saturation for only the midtones.

Make sure the Adjustment Type is set to All Color Tones.

Increase the saturation for all color tones by increasing the Saturation Factor until the bottom image looks correct.

Press the Accept button.

The changes are applied to the layer and the Saturation/Value window closes.

Choose Paint Edit > Color correction > Saturation & value

again to reopen the window.

Zoom in and pan into the area of the image that has midtone colors (using the buttons at the top of the Saturation/Value window).

Decrease the saturation for only the midtone colors by changing the Adjustment Type to Only Midtones, and decreasing the Saturation Factor until the bottom image looks correct. (You may also lighten the midtones by decreasing the Value Factor.)

Zoom back out to see the overall effect of the change in the bottom image.

Press the Accept button at the bottom of the Saturation/Value window.

The changes are applied to the layer and the Saturation/Value window closes.

Modify brightness and contrast in an image

This tool allows you to adjust the tonal range of an image by providing sliders for brightness and contrast. It also lets you compare the original image with a preview image showing the modifications as you change the slider values.

Example Workflow

Import the image (File > Import > Canvas image

) or pick the layer to be adjusted in the canvas Canvas Layer Editor.

Choose Paint Edit > Color correction > Brightness & contrast

. The active layer is loaded into the Brightness/Contrast window.

Zoom in and pan to see the area of the image that provides the best view (using the buttons at the top of the Brightness/Contrast window).

Decide what tonal value to change. In this example, we'll increase the contrast for all color tones. Then we'll make the shadows darker and the highlights brighter.

Make sure the Adjustment Type is set to All Color Tones.

Increase the contrast for all color tones by increasing the Contrast Factor until the bottom image looks correct.

Press the Accept button.

The changes are applied to the layer and the Brightness/Contrast window closes.

Choose Paint Edit > Color correction > Brightness & contrast

again to reopen the window.

To make the shadows darker, set the Adjustment Type to Only Shadows, then decrease the Brightness Factor, until the bottom image looks correct..

Press the Accept button.

The changes are applied to the layer and the Brightness/Contrast window closes.

Choose Paint Edit > Color correction > Brightness & contrast

again to reopen the window.

To make the highlights brighter, set the Adjustment Type to Only Highlight, then increase the Brightness Factor, until the bottom image looks correct.

Press the Accept button at the bottom of the Brightness/Contrast window.

The changes are applied to the layer and the Brightness/Contrast window closes.

Replace Color

Isolate and change a precise color range without the need of complex masking.

The replace color tool is the most complex color adjustment tool but it is extremely powerful because it allows very fine control of hue, saturation, and value ranges.

Import the image (File > Import > Canvas image

) or pick the layer to be adjusted in the Canvas Layer Editor.

Choose either the Paint Edit > Color correction > Color replace (HSV)

(Hue, Saturation, Value) or Paint Edit > Color correction > Color replace (HSL)

(Hue, Saturation, Luminance) tool. The active layer is loaded into the Color Replace window.

Decide what to adjust: hue, saturation, and/or value, and click the check marks in the right of this window. In this first example, modify only the hue of the sky without changing any other color of the car.

Using the eye dropper tool, select the sky color. Notice how the From hue region changes so only hues that are defined by the from range can be modified. In the image below, the To hue range is set to cyan. You may need to broaden or narrow the From color range using the sliders or by using the eye dropper + or - tools.

Use the center arrow to shift the To hue range to different regions, such as the blue region of the hue spectrum.

Or try yellow:

To see what precise areas of the image are protected from change, switch the preview area to Selection.

Choose Selection to display the mask in the preview box. Protected areas are masked pink, and unmasked areas are white. Partially masked areas (areas covered with a semitransparent mask) appear as varying levels of pink according to their opacity. In this example you can see the car is protected but any sky reflections in the car will change. Note how this image has almost black areas in the floor that contain an orange > yellow hue.

If the replace color range is incorrect, pick the eyedropper + to add areas, or use the eyedropper - button to remove areas.

Adjust the tolerance of the hue mask by dragging the outer slider arrows. This controls the feathering to which related colors are included in the selection. In the example below we have adjusted the tolerance sliders so they feather into the red hue of the car; this means the mask is semi-transparent.

The icons to the right of the color range sliders allow fast alignment of the to and from range.

This example shows From hue and feather. The range has been reset using the eyedropper, clicking the red of the car and the To hue range has been moved to blue.

Zoom into the front of the car and adjust the from outer sliders to remove the red tint from the body panels.

Now turn on the Saturation range and reduce the To range to make it smaller than the From range. This reduces the saturation of the blue car.

This example shows how the hue To range has been restored to the original but the saturation range is dramatically reduced, removing red from the car body panels.

Now adjust the To hue to green, broaden the saturation and turn on the value range, and move the To value to the left to darken the body panels.

The color replace tool is extremely powerful for adjusting the hue, saturation or value of an image and can automatically mask the image.

Remove a color by making it transparent

Select a color then use the Erase Paper plug-in.

This feature is available in all AliasStudio products.

How to make all areas containing a given color transparent

Choose Utilities > Plug-in Manager

and select the erasePaper plug-in in the Paint section (put a check mark in both columns).

The Erase Paper tool plug-in is added to the Paint Edit palette.

In the Canvas Layer Editor, select the canvas and layer you want to affect.

Select the color you want to make transparent. (Choose a Brush tool to open up the color swatch in the upper left corner of the interface, which displays the default brush color.)

The quickest and most accurate way to select a color is by using the eye dropper. Click the eye dropper then click the color you want on the canvas.

Choose Paint Edit > Erase Paper

The color is removed.

In DesignStudio, Studio and AutoStudio, the image layer is duplicated before the color is removed. The new layer contains the original un-erased version, which you can access through the Canvas Layer Editor.

Repeat the process for another color, or another layer, if needed.