Levels and Color

This basic transformation lets you adjust the saturation, color balance, dynamic range and brightness and contrast of an image. Since brightness, contrast, color balance, and saturation interact with each other in ways that are difficult to pre-visualize, it can be useful to adjust all these variables at once. Levels and Color is a simplified version of the Adjust transformation which is more powerful, but more complicated.

Levels and Color starts out by analyzing the input image to determine the dynamic range of the input image, i.e. its darkest and lightest points. These points are represented as tic marks below the gray scale for Dynamic Range (see below).

Amount

The Amount control lets you control how much of the Levels and Color transformation is applied to the input image. You can apply a percentage of the transformation to the entire image, or you can specify an amount mask to restrict the effects of the transformation to only part of the input image.

Midtones

Adjusting this slider lightens or darkens the mid-tones of the image without affecting its shadows or highlights. You can control the brightness levels of the shadows and highlights using the Contrast and Dynamic Range controls (see below).

Contrast

Adjusting this slider increases or decreases the mid-tone contrast of the image at the expense of some loss of shadow or highlight detail. You should recheck your contrast setting after making a change to the Dynamic Range control since these two settings are closely related.

Dynamic Range

Adjusting this dynamic range slider alters the highlight brightness and shadow darkness of the input image. The original light and dark points in the input image are marked with small tic marks under the slider. You change the highlight brightness of the image by dragging the white slider and you change the shadow darkness by dragging the black slider. Moving the black and white sliders toward each other reduces image contrast; moving them apart increases it.

Setting the black (shadow) slider to 0% forces the darkest parts of the input image to be pure black while still preserving shadow detail. If you move the black slider beyond this point to the left into negative values, the result image will continue to become darker by making more and more of the shadow areas black as well. The effect is often more dramatic at the expense of shadow detail.

Setting the white (highlight) slider to 100% forces the lightest parts of the input image to be as bright as possible while still preserving highlight detail. The effect depends considerably on the color space you have selected (see above). If you move the white slider beyond this point to the right to values greater than 100%, the result image will continue to become lighter by setting more and more of the highlight areas to maximum brightness as well. This creates an effect of intense brightness at the expense of highlight detail.

As a shortcut, Shift-Clicking on the slider sets the range to 0% .. 100%. Ctrl-clicking on the slider resets the black and white points to line up with the tic marks.

Saturation

Adjusting this slider alters the saturation of the image. Moving the slider to the right increases the saturation; moving the slider to the left decreases the saturation. Moving the saturation slider all the way to the left yields a black and white image. Moving it all the way to the right produces an image with unnaturally intense colors. Placing the slider in the middle leaves the saturation of the input image unchanged. The saturation slider is not displayed if the input image is black and white.

Color Balance

This control alters the color balance of the image by applying a color filter to it. You can set the color balance in two ways: by clicking on the input image window or by selecting a color using the color picker.

Clicking on the input image window samples the color of the input image at the point you click and sets the color balance to the complement of that color. This has the effect of neutralizing in the result image the color you select in the input image. Thus, if you can find a spot in the input image that should be a neutral gray, clicking on it will automatically compute the correct color filter to apply to the image to achieve this effect.

If you prefer, you can click on the small square that makes up the Color Balance color control bring up a color picker . You can use this control to specify a filter color directly from the color wheel or the filter bank.

If the input image is black and white, you can use the color balance control to tint it. For a more powerful way to tint black and white images, see the Tint transformation

Color Space

If the input image is color then this control lets you select whether you want to work in the HSV or HSL color space. When you lighten an image using HSL, it becomes whiter and may appear washed out. When you lighten an image using HSV, it retains the relative proportions of its red, green and blue color components, but is limited in how bright it can get by the value of the largest RGB channel.

If the input image is black and white, then the Color Space control is not displayed.

Saturation

Adjusting this slider alters the saturation of the image. Moving the slider to the right increases the saturation; moving the slider to the left decreases the saturation. Moving the saturation slider all the way to the left yields a black and white image. Moving it all the way to the right produces an image with unnaturally intense colors. Placing the slider in the middle leaves the saturation of the input image unchanged. The saturation control is not displayed if the input image is black and white.

Settings Menu

Full Dynamic Range -- aligns the black and white markers with the ends of the gray scale. This is equivalent to Shift-Clicking the Dynamic Range slider.

Reset Dynamic Range -- toggles the Reset Dynamic Range setting.

When checked, this aligns the black and white markers with the tic marks below the slider gray scale, causing the dynamic range of the input image to remain unchanged. If unchecked, the dynamic range of the input image is stretched from its initial range to the range indicated by the Dynamic Range slider. Reset Dynamic Range it automatically unchecked if you change the dynamic range.

When some upstream transformation changes the input image or when you load a saved script file that includes a Level and Color transformation, its black and white points are recomputed. If Reset Dynamic Range is checked, the black and white dynamic range markers are then set to the range of the new image, causing its dynamic range to be left unchanged -- otherwise, the black and white markers remain at their previous positions, causing the dynamic range to be stretched.

Reset (Brightness/Contrast/Color Balance/Saturation) -- resets a single setting to its neutral value, leaving the others unchanged.

Probe Size (1x1/3x3/5x5/7x7/9x9)

These options let you control the sample size used by the color balance probe. Larger probe sizes are useful for obtaining an average reading of any area of the image that does not have a smooth texture; smaller probe sizes let you get precise readings of very small areas.