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Functions for Picture Enhancement
Quick Fix
This function automatically fixes a picture based on its available picture information and on an analysis of the picture. It does not interfere in matters of exposure level. This function is good for quick batch edits.
You can reach it via Edit | Adjust | Quick Fix [Ctrl+0] in the Browser, and via Adjust | Quick Fix in the Editor.
There are no settings for this function. It performs automatic contrast stretching, local contrast enhancement (and in some cases sharpening), saturation editing, and noise reduction with the help of the picture’s EXIF information.
Levels
The Levels tool is an important tool for correcting the brightness levels in a picture. You can use this function to, for example, change a picture's "black point" and "white point" using a histogram. You can also use it to lighten or darken the midtones of a picture—to perform gamma correction.
To reach this window, use Edit | Adjust | Levels [Shift+L] in the Browser, or Adjust | Levels in the Editor.
Besides manual editing, you can also use it for automatic edits via the window's Automatically correct colors option. In the left part of the window, you can see a histogram preview and settings for manual edits. The Channel menu lets you choose which color channel to edit. RGB means the brightness channel. You can configure all these settings separately for each channel. The most basic settings when adjusting levels are the input and output levels and the gamma-correction coefficient. The gamma correction slider is located between the input values and output values. It determines colors' brightness in the midtones. All five values can be entered either directly using a number in the corresponding field, or visually, by clicking and dragging the corresponding triangle under the histogram and the brightness scale.
You can use the Black point and White point eyedroppers to select an input level for individual brightness elements by manually selecting a color directly from a preview pane. Clicking the brightest and darkest pixels in the picture generally gives the most useful white and black points.
When you turn on automatic mode, input levels for the individual channels are set automatically. When you use Automatic contrast, they are set the same for all channels. When you use Automatic levels, they are set for each channel independently. Automatic contrast "stretches" the brightness of the whole photograph to the maximum values, while Automatic levels "stretches" individual colors separately, and thus can change the picture's tinting. You can sometimes take advantage of this to remove tinting from a picture. The Target colors and cutoffs controls sets what colors to map the lightest and darkest areas to. The cutoffs aspect of it sets how much of the histogram should be cut off on the left and the right to ensure that the actual effective white and black points are used, rather than one of a few unrepresentative pixels that lie beyond them.
Curves
Curves serve for correcting tone range and color balance. To reach this function, use Edit | Enhance | Curves [Shift+C] in the Browser menu or Enhance | Curves in the Editor menu.
Work with curves lets you very precisely set the individual color channels in a picture. Its conversion function is shaped like a curve that can be reshaped as necessary.
The horizontal axis shows input values. The vertical axis shows output values.
The Channel menu lets you choose which color channel to edit. RGB means the brightness channel. You can configure all these settings separately for each channel. To get a better idea of how the individual RGB channels are responding, it can be good to turn on Show color elements. The Linear option determines whether an interpolation curve should link the nodes you add to the curve, or a series of straight lines should link them instead.
Click Select pixel in image if you would like to use a pixel from the picture itself to set the color for the current node. If you hold down [Shift] at the same time, a node with this color will be added to the curve.
You can easily edit the curve using the mouse. Clicking anywhere on the curve between the red endpoints will add a new node to the curve. You can click any node on the curve to then move it to another position, using either drag-and-drop, the arrow keys, or direct editing via the Input and Output fields. If you right-click on a node, you can delete that node. You can also select a node by left-clicking it and then pressing [Del]. You can keep on deleting nodes until the only two nodes left are the red endpoints. Click Erase Curve to restore the original “curve” for the selected Channel. That curve is formed simply by a straight line leading from the top left to the bottom right. If the curve is erased for all color channels, then the picture will stay unchanged. Clicking Automatic Contrast or Automatic Levels will erase the current curves within the R, G, and B channels and set up new ones corresponding to each button’s purpose. To control the sensitivity of these automatic settings, use the Cropping controls (separate for Lights and Shadows).
Tips
- Shifting the endpoints will change the input values for the white point and black point, just as if you were using the Levels function.
- Moving the nodes horizontally to the positions where the histogram for the RGB channel “begins” and “ends” will cause an effect similar to using Automatic Contrast within the Levels filter: the brightness of the whole photo will be “stretched” to the maximum values.
- Moving the nodes horizontally to the positions where the histogram for the R, G, or B channel “starts” or “ends” causes an effect similar to when you are using Automatic Levels: the individual color channels throughout the photo will be “stretched” to their maximum values. If each channel is edited using a different curve, then the picture’s tinting will change.
- If you wish to influence shadows, create and move nodes on the left sides. If you wish to influence lights, work on the right side.
- Moving a node you have created down on the curve or to the right will darken a part of the tones in the picture. Moving a node up or to the left lightens part of the tones in the picture.
- The curve you create should have an ascending path; if it is descending in some section, that section will be tinted.
- But to get the most contrast for a photo, create an S-curve. This will slightly darken part of the midtones, while “stretching out” the remaining midtones and light tones.
In practice, using the Curves tool well simply requires experience. There are no particular settings that can be recommended universally, because each photo has different tonal characteristics and requires specific edits. To gain the experience mentioned above, you mainly need to keep using the Curves window and pay a close eye to the preview pane and to changes in the histogram.
More Information
There’s No Need to Fear RGB Curve Editing. Here Are 4 Practical Examples of How to Use It.
How to Use Curves to Adjust Image Exposure
Enhance Colors
Use this function to adjust a picture's colors, brightness, and contrast. To call up this function, use Edit | Adjust | Enhance Colors… [Ctrl+1] in the Manager or use Adjust | Enhance Colors… in the Editor.
This function offers: controls for editing the R, G, and B color channels, hue, saturation, vibrance, and lightness, and brightness and contrast, as well as a gamma correction control.
The Mode (Normal, Lights Online, Shadows Only) and Preserve colors controls affect gamma correction only. Preserve colors ensures that colors' hues will not change even after major brightening, so that the picture will not start to look "washed-out." During edits to color channels, this option ensures that the picture's overall brightness will be preserved.
This window also contains a function for Automatic Contrast.
Adjust Color Temperature
You can use this function to manually correct pictures that are suffering from tinting due to bad white balance settings during picture-taking.
To reach this window, use Edit | Adjust | Adjust Color Temperature… [Ctrl+2] in the Browser window, or Adjust | Adjust Color Temperature… in the Editor menu. You can define the color temperature by setting a neutral color or by entering a color temperature.
By manually setting a neutral color lets you set a "gray" point. This is a pixel that should have no tinting after the edit. You cannot use for this purpose a point suffering from maximum blowout (a pure white pixel), because no color shift can be determined on the basis of pure white.
You can set a lighting temperature using two sliders. The first slider is for shifting colors based on the picture's current lighting temperature, from blue to yellow. The second slider is for correction from green to purple.
Enhance Exposure
Use this function to adjust a picture’s brightness and contrast.
To access it, use Edit | Adjust | Enhance Exposure… [Ctrl+3] in the Manager or Adjust | Enhance Exposure… in the Editor.
- Exposure – use this to correct exposure by up to +/-3 EV.
- Contrast – use this to control the picture’s overall contrast.
- Lights – use this to darken light areas in the picture.
- Shadows – use this to lightens dark areas in the picture.
- White point – tones brighter than this level are converted to pure white.
- Black point – tones darker than this level are converted to pure black.
- Texture – highlights local contours without any major effect on the photo’s overall contrast.
- Clarity – use this to change local contrast at contours in the picture.
- Dehaze – dehazes a hazy picture or adds haze to a picture.
Sharpen
This function can at least partially repair a picture that suffers from blurring. It is a good idea to use this function after resizing a picture.
To reach this function, in Manager module use Adjust | Sharpen… [Ctrl+5] to sharpen pictures. The most important option in this window is the sharpening type.
- Simple sharpening is a quick way to sharpen fine details in certain situations such as after you have shrunk a picture. For this type, you can choose an effect strength and whether or not to use the Brightness method.
- Unsharp mask has its roots in film-camera technology. It sharpens only highly visible edges and borders. For this type, you can choose an effect strength, a radius, and a threshold, and toggle the Brightness method.
- Gaussian sharpening is a method for removing Gaussian blur. For this method, you can choose an effect strength, a radius, and noise suppression.
- Overall sharpening gets rid of overall blur in a picture. For this method, you can choose an effect strength, a radius, and noise suppression.
- Soft sharpening sharpens a picture’s fine details while suppressing rough structures, making it useful for sharpening e.g. portraits. You can adjust the effect strength.
- Smart Sharpen lets you restrict sharpening to just the places where it’s really needed. The Preserve Contours option makes sure that the sharpening ignores contours that are already sharp enough and applies only to the picture’s less sharp areas instead.
The Brightness Method setting means that the filter will only be applied to the picture’s Lightness element within the HSL color model. This prevents the shifts in color that can otherwise happen around borders when you are sharpening strongly.
Differences Among Sharpening Methods
The various sharpening methods have considerably varying effects on pictures. While the Unsharp mask sharpens mainly highly visible edges in a picture, the other methods always sharpen the whole picture, thus emphasizing all details. In practice this means that in low-quality photos – whether they suffer from noise or excessive compression – the Unsharp Mask is the most advantageous of the methods, since the remaining ones would overly emphasize the less attractive parts of the picture.
Use the unsharp mask method to eliminate unsharpness that arose while taking the picture, scanning, etc. This method is very appropriate for photographs because it uses the details of the picture itself for its decisions. The basic idea behind this method is simple. A blurred copy of the original picture is created, and then that copy is “subtracted” from the original. The new copy that results from this has highlighted edges. This new copy is then “added into” the original. The Radius sets how much the mask is blurred, so its size is very important. Too high a value will cause oversharpening, which will show up as bright (or even shining) contours around any edges in the picture. The Threshold determines how different two brightness values should be before they are treated as an edge. A value of 0 means that the effect will be used on all pixels in the picture. If the effect overly emphasizes noise, then we recommend that you experiment with values in the range from 2 to 20.
The Gaussian sharpening and Overall sharpening methods are designed to remove concrete types of blurring using what is called a convolution matrix. The Overall type can rescue pictures damaged by unsharpness during picture-taking itself. Gaussian sharpening helps pictures that became blurred during processing – e.g. during shrinking. Radius sets how much of each pixel’s surroundings will be included in calculations. A larger radius will be subjectively perceived as a much stronger sharpening effect. The Noise suppression can prevent oversharpening without preventing sufficient sharpening.
When you shrink a picture using supersampling, this causes overall blurring, not Gaussian, but this is somewhat of an exception. Blurring that arises during picture-taking tends to lie on the border between Gaussian and overall blurring.
More Information
How to Sharpen Your Photos: Beat the Blurry Blues
[Infographic] How to Sharpen a Photo
Blur
This function offers several methods for blurring photographs, both to enhance them photographically and for artistic purposes.
To reach this window, use Edit | Adjust | Blur… [Ctrl+6] in the Browser, or Adjust | Blur… in the Editor.
The filter offers six types of blurring: Fine, Gaussian, Overall, Directional, Rotational, and Zoom. The first type is good for creating weak blurring. For a stronger effect, use Gaussian or Overall. The other blurring types have some extra settings. For Directional blurring, you can set the Direction. For Rotational and Zoom blurring, you can set the X and Y Center of the blurring. (You can also select the center directly from the picture, using an eyedropper.) The first slider, Strength, is shared by all blurring types. The High quality option increases the precision of calculations at the price of increased time for calculating the blurring.
Remove Noise
To remove noise from a photograph, use Edit | Adjust | Remove Noise… [Ctrl+Shift+N]. Zoner Studio’s noise removal function can be used to remove both the noise typical for long exposure times (sometimes called “hot pixels” noise; called “salt and pepper” in the program) and additive noise. Both of these removal types can also be applied at the same time.
Remove “salt and pepper” noise – for this type of noise reduction there is just one control; use it to set the Noise type in the picture.
Remove additive noise – with default settings, when you are removing additive noise, you can use the Luminance and Colors sliders to set the noise reduction level independently for the picture’s luminance and color elements.
Advanced
Use Advanced to display the more advanced noise-reduction controls, intended for experienced users.
For better, though slower, noise reduction, or vice-versa, use the Quality setting.
Besides making global changes using the Luminance and Colors sliders, you can also selectively adjust the amount of noise reduction for individual colors or image luminance levels. For this, use the controls under Local correction, by color and Local correction, by luminance. The core of each of these controls is a color or luminance gradient, beneath a curve with several nodes. Drag the nodes to reshape the curve and thus increase/decrease noise reduction for individual colors/luminance levels. Click anywhere on the curve between existing nodes to add a new node. To delete a node, press [Del]. Use the eyedropper to select a color or luminance level directly from the picture.
Very strong noise in a picture often creates distracting color stains that persist even after noise reduction. Use Color stain removal to eliminate this problem. Choose the intensity of color stain removal carefully. Too much intensity leads to excessive loss of detail in the image.
To reduce noise smartly, so that noise is removed as much as possible, but only a few details are lost, the program must determine the picture’s noise level correctly. Therefore, a rather detailed noise analysis is performed before noise reduction starts. However, in some cases this analysis can still guess the noise intensity level incorrectly, causing either incomplete or overly-aggressive noise reduction. In such cases, under Image noise intensity , change the detection method to Set manually and adjust the detected noise intensity. It can be adjusted independently for colors and luminance. We recommend setting both noise reduction sliders to 100% and adjusting the noise intensity while watching the preview, until the intensity is at a level where noise reduction is strong, but loss of image detail is still acceptably low. Then put the noise reduction level sliders back to the values you want.
Just after you call up the noise reduction filter, it analyzes the noise in the picture and then runs noise reduction. This process can take a long time on large images. However, changing most settings does not demand running the process again, and so is significantly faster.
More Information
Say Goodbye to Noise—How to Get Rid of Noise in a Few Clicks
Chromatic Aberration
To fix photos that are suffering from chromatic aberration, use Edit | Adjust | Chromatic Aberration [Ctrl+Shift+A].
Chromatic aberration can have any of several causes; one cause is different refraction of rays of light with different wavelengths. Its most common effect on a picture is to add a purple, sometimes also green or blue blurred contour in places with high contrast. Zoner Studio offers a very easy-to-use tool for eliminating this problem.
Zoner Studio offers several possibilities for correcting photos with chromatic aberration. To reach the correction feature in the Manager, use this top-menu item: Edit | Adjust | Chromatic Aberration [Ctrl+Shift+A]. In the Editor, use Edit | Adjust | Chromatic Aberration instead.
In the Develop module’s Camera and Lens controls, two differing chromatic aberration correction approaches are offered:
- Automatic correction, which is only offered for RAW files, and
- Manual correction.
Two options are available for automatic correction. If a lens profile is available, and that profile contains the necessary data, then you can use correction Based on Profile. If no profile is available, or it does not contain the data, you can use Based on Image Analysis instead.
Manual correction offers controls for suppressing colors along two scales: Red–green and Green–blue. These shift the mentioned colors against each other to suppress the defect. This approach is most useful when the chromatic aberration is absent in the middle of a picture and grows towards its edges. If it takes on some other form instead, try eliminating it using Defringe in the Develop module. Outside of the the Develop module, you can try this:
When there is no chromatic aberration in the center of a picture and it becomes gradually stronger towards the edges, you can fix it using the “Red–green” and “Blue–yellow” sliders. By using these to “push” the color channels towards each other, you will fix the defect.
But if the chromatic aberration manifests itself in another way or if the mentioned controls are not enough to suppress it, you can turn on the Desaturate a particular color controls. These let you selectively suppress colors in the picture, with a tolerance level of your choice.
Barrel Distortion
You can fix photos suffering from barrel or pincushion distortion using Edit | Adjust | Barrel Distortion [Ctrl+Shift+D].
Barrel and pincushion distortion are frequent lens defects that have unpleasant effects on photographs of architecture and objects with straight edges. Use the slider here to set how strongly the photo's contents should be "pushed in" or "pushed out." When correcting barrel distortion, the Auto-crop option here is quite useful. You can set a quality level for this function; this sets what algorithm is used by the function. The low-quality but fast Nearest neighbor method is good while seeking the right amount of correction to use. The high-quality but slow Bicubic method is best once you are ready to apply the correction.
You should remove barrel or pincushion distortion from a picture before making any other edits to it
(and especially before cropping it or correcting collinearity or perspective).
Vignetting
To remove vignetting from a picture or add vignetting, use Edit | Adjust | Vignetting… [Ctrl+Shift+V] in the Browser or Adjust | Vignetting… in the Editor.
Vignetting is uneven exposure throughout a photo, with darkening towards the corners. Typical causes of vignetting are add-on lenses and filters for wide-angle lenses, and low-quality lenses.
The mask is created based on the Radius setting, which sets how quickly the picture darkens towards the corner. This second antivignetting mode is only useful for uncropped pictures, because it always places the center of the correction in the center of the picture. Use the Effect strength slider to set the amount of vignetting to add or remove. (To add vignetting, use negative values.)
More Information
Vignetting—An Issue and a Blessing
Interlacing
This window helps you fix problems surrounding interlacing, a common phenomenon in pictures obtained from video.
Digital cameras and other video equipment work, for historical reasons, with interlaced pictures. Such picture contain two "fields"—half-pictures—that can each come from different scenes, especially if the source video sequence contained a large amount of motion. The first field is stored in the odd rows of the picture; the second field is stored in the even ones. lf the scene is static, without movement, then the picture has full resolution, and no deinterlacing is needed. (The same applies for pictures taken from classical film video, which also usually contains two fields in each picture.) If the scene changes fundamentally between frames, then the picture will contain two fundamentally differing fields. The vast majority of camera stills are somewhere inbetween: some parts are moving; others, static.
Use Edit | Adjust | Interlacing… in the Browser window or Adjust | Interlacing… in the Editor window to reach the Interlacing window, or press [Ctrl+Shift+L].
Zoner Studio can help you adjust and fix photos containing interlaced fields. Different methods are the right solution for different pictures—sometimes you will want to only deinterlace a part of a picture; sometimes you will even want to use different (de)interlacing tools for different part of a picture!
- Blended clipping—this method is the one generally recommended. It tries to intelligently join both fields in areas without motion, so as to increase the picture's final resolution. In areas with motion, the program needs advice on a "preferred" field that should be kept (and the other thrown out).
- Blend fields—this method joins both fields into one picture. In places with motion, the picture will be "double" and blurry.
- Interpolate field—only the preferred field will be used for calculations; the other field is thrown out and replaced with lines determined via interpolation.
- Duplicate field—only the preferred field will be used for calculations; the other field is thrown out and replaced with lines determined via duplicating lines from the preferred field.
- Subsample field—only the preferred field is used. Instead of filling in lines between it, it is shrunk using interpolation (subsampled), so that the ratio of sides in the final picture remains correct. The resulting picture will have 1/4 the resolution of the original.
- Swap fields—This method is not a deinterlacing method at all. It swaps the two fields instead. This is useful because some programs erroneously save fields in the opposite of the correct order. Swapping solves this.
The Prefer first field checkbox sets which of the two fields is the "preferred" one. The right setting for this checkbox will vary from case to case.
Joining threshold—this sets the minimum amount of difference that is judged to be motion when you are using Blended clipping. If you set it too high, then blended clipping may not catch and remove all interlacing artifacts in the picture. If you set it too low, you will effectively be needlessly reducing the picture's resolution, because more of the non-preferred field will be thrown away and replaced via interpolation than is necessary. We recommend values from 10 to 25.
Test brightness, not color—motion detection when using Blended clipping is based on differences in either color or brightness for each pixel in the first and second field. Detection based on color is most useful for drawn pictures or other scenes with large areas of one color (above all animated films). Brightness-based detection works well for parts of a picture with transparent elements (like television graphics, or logos).
You should de-interlace a picture before making any other edits to it (and especially before resizing it).