Main Tab Sheet

 

The Main tab sheet contains a curve tool and sliders for adjusting the brightness, contrast, color and saturation of the whole image.

Click on the sub tab bar at the top of the tab sheet to switch between different control groups. The arrow-down button displays a menu with various presets that activate the effects on the selected sub tab. So depending on the selected sub tab a different menu is displayed.

 

The Curve Diagram

There are seven different curves plus five sliders for each curve. One curve is located on the Tone sub tab, two are on the Color sub tab, three on the RGB sub tab and another one is on the Saturation sub tab. Each of them changes different image values. The Tone curve affects all pixel values (thus producing brightness and contrast adjustments), the Color and Bicolor curves colorize the image with one or two colors, the three RGB curves affect the three color channels individually and the Saturation curve changes the saturation of all pixels.

The curve diagram offers an advanced way to change the brightness, contrast, color or saturation of the whole image. The basic idea is to transform certain pixel values into other values. The horizontal axis of the curve diagram represents the original input values from 0 to 255. The vertical axis represents the new output values. The label at the bottom left corner of the curve shows which value is transformed into which other value if you move the mouse cursor over a point of the curve.

As long as the curve lies on the base line, which runs diagonally from the bottom left to the top right corner, no pixel value is changed. If the curve runs above the base line, then the pixel values are increased. If it runs below, the pixel values are decreased, which affects the brightness. The bottom left part of the base line represents the shadows and the top right part represents the highlights. If you use an S-shaped curve, then the shadow values are decreased and the highlight values are increased, which raises the contrast. An inverted S-curve decreases the contrast.

To set a new curve point click at a location in the curve diagram, at which you want the curve to pass through. But you can also click somewhere, hold down the mouse button and drag the mouse to move the new curve point and shape the curve accordingly. To create a more complex curve you usually need to set two or more curve points. To select a curve point simply click on it. To remove a selected curve point press the Del or Backspace key or simply drag it outside of the diagram.

The curve that you shape with curve points is displayed as a black line. If you use the sliders below the curve diagram, you will see a red curve line appear. This red line represents the combined output curve that is shaped by the black curve as well as the slider values.

You can also adjust the curve by activating the eyedropper icon and dragging with the eyedropper tool on the preview. Depending on the pixel that you click on a curve point will be created, which is then moved up or down while you drag your mouse up or down. For more information see the Tools & Reset page.

 

Tone

The Tone sub tab allows you to adjust the image tone, meaning the brightness and contrast of the image.

With activated Sat Fix check box the curve and sliders are applied only to the luminance channel of the image. This usually keeps the saturation constant, which can be an advantage or disadvantage depending on the image. When the Sat Fix check box is deactivated, the curve and sliders are applied to all channels.

The Intensity slider increases or decreases amplitude of the curve and the intensity of the controls on the Tone sub tab. It influences both the black curve as well as the other sliders below the curve. Slider values below zero make the red output curve move towards the base line thus decreasing the Tone effect. Values above zero make the red curve move further away from the base line thus increasing the Tone effect. At a value of zero the Intensity slider does not influence the curve and the sliders.

The Brightness slider increases or decreases the brightness of the image in EV (Exposure Value) steps from -3.0 to +3.0.

The Shadows and Highlights sliders increase or decrease the brightness in the dark and bright areas of the image. Shadow values above zero make the shadows darker whereas values below zero brighten them up. Highlight values above zero brighten the highlights whereas values below zero darken them. If both sliders have similar slider values, then the contrast of the image is changed. To adjust the contrast without having to drag both sliders simultaneously, you can also activate the check box at the left to turn both into a single Contrast slider. Contrast values below zero make some details more visible, but may create a faded look. Values above zero increase the contrast and give the image more punch, but may stretch shadow or highlight details too much.

The Exposure slider stretches the tonal range of the image. It performs a white point adjustment for positive slider values and a black point adjustment for negative values. Please use with care, because it can easily blow highlights or suppress shadows.

 

Color

 

The Color sub tab lets you colorize the image with one or two colors. With the Color option selected in the list box, you have only one color box. Bending the curve above the base line brightens the image with this color. If you bend it below the base line, the color is used to darken the image.

With the Bicolor option you have two color boxes. If the curve runs above the base line, the first color is applied. If it runs below, the second color is applied to the image. To colorize the image with both colors, you need to make the curve run below as well as above the base line. To choose another color click on one of the color boxes. The arrow-down button also displays a menu with different preset items after you switched between the Color and Bicolor options.

The Intensity slider increases or decreases amplitude of the curve and the intensity of the controls on the Color sub tab. It influences both the black curve as well as the other sliders below the curve. Slider values below zero make the red output curve move towards the base line thus decreasing the color effect. Values above zero make the red curve move further away from the base line thus increasing the color effect. At a value of zero the Intensity slider does not influence the curve and the sliders.

The Color slider increases or decreases the brightness of the color in the image.

The Shadows and Highlights sliders increase or decrease the brightness of the color in the dark and bright areas of the image. Shadow values above zero make the shadows darker whereas values below zero add a brighter color. Highlight values above zero add a brighter color the highlights whereas values below zero make them darker. If both sliders have similar slider values, then the color contrast of the image is changed. To adjust the contrast without having to drag both sliders simultaneously, you can also activate the check box at the left to turn both into a single Contrast slider. Contrast values below zero make some details more visible, but may create a faded look. Values above zero increase the color contrast and give the image more punch, but may stretch shadow or highlight details too much.

The Amplify slider stretches the tonal range of the image according to the chosen color(s). Please use with care, because it can easily blow highlights or suppress shadows.

 

RGB

The RGB sub tab also adjusts the color of the image. But it works quite differently from the Color sub tab. You have to adjust three curves instead of one curve plus a color box. This requires an understanding of how the three red, green and blue color channels are combined to create a certain color look, but it also offers more possibilities. The RGB sub tab lets you switch between the Red, Green and Blue curves, which represent the three color channels of the RGB color model. So you can independently adjust the red, green and blue color channels of the image. You can switch between the three curves with the list box at the top left corner of the tab sheet.

The Intensity slider increases or decreases amplitude of the curves and the intensity of the controls on the RGB sub tab. It influences both the black curve as well as the other sliders below the curve. Slider values below zero make the red output curve move towards the base line thus decreasing the color effect. Values above zero make the red curve move further away from the base line thus increasing the color effect. At a value of zero the Intensity slider does not influence the curve and the sliders.

The Color slider increases or decreases the brightness of the selected color channel. Negative values add the antagonistic color of the color channel (cyan for the red channel, magenta for the green channel and yellow for the blue channel) to the image whereas positive values add the color of the color channel.

The Shadows and Highlights sliders increase or decrease the brightness of the color channel in the dark and bright areas of the image. Shadow values above zero add the antagonistic color (cyan for the red channel, magenta for the green channel and yellow for the blue channel) to the shadows. Values below zero add the color of the color channel to the shadows. Highlight values above zero add the color of the color channel to the highlights. Values below zero add the antagonistic color (cyan for the red channel, magenta for the green channel and yellow for the blue channel) to the highlights. If both sliders have similar slider values, then a bicolor effect occurs, which consists of the color of the color channel and its antagonistic color. To create this effect without having to drag both sliders simultaneously, you can also activate the check box at the left to turn both into a single Contrast slider.

The Exposure slider works similarly to the Color slider, but creates a more extreme effect.

 

Saturation

The Saturation sub tab can be used to change the saturation of the image.

Normally a certain saturation value is transformed into another saturation value according to the curve. If you activate the Tonal check box then the saturation value is increased or decreased at a certain brightness level, so that you can adjust the saturation in the shadows, midtones and highlights differently. That means at a certain brightness level a certain saturation increase or decrease takes place.

The combo box below the Tonal check box defines the method with which the image saturation is processed. The Normal option uses classic saturation adjustment via the HSL color space whereas the Mild option stays in RGB space, which avoids color artifacts at extreme settings. The remaining option protects a certain color from the saturation adjustment. For example, the Red option keeps the saturation of the red image areas more or less constant, even if it is increased in the rest of the image.

The Intensity slider increases or decreases amplitude of the curve and the intensity of the controls on the Saturation sub tab. It influences both the black curve as well as the other sliders below the curve. Slider values below zero make the red output curve move towards the base line thus decreasing the saturation effect. Values above zero make the red curve move further away from the base line thus increasing the saturation effect. At a value of zero the Intensity slider does not influence the curve and the sliders.

The Saturation slider increases or decreases the saturation of the image.

If the Tonal check box is deactivated, the Low Sat. and High Sat. sliders increase or decrease the saturation in the low and highly saturated areas of the image. If the Tonal check box is active, the same sliders, now named Shadows and Highlights, increase or decrease the saturation in the dark and bright areas of the image. To adjust both sliders simultaneously activate the check box at the left to turn both into a single Balance slider. Positive Balance values increase the saturation in highly saturated or bright areas (depending on the Tonal check box) and decrease it in low saturation or dark areas. Negative Balance values do the opposite by decreasing the saturation in highly saturated or bright areas and increasing it in low saturation or dark areas.

The Exposure slider works similarly to the Saturation slider, but creates a more extreme result.