19.8. Viewing and Editing Images

digiKam comes with a comprehensive image viewing and editing suite consisting of various plug-ins. To enter digiKam's viewing and editing mode, double-click an image thumbnail. To use the plug-ins, you need to install the digikamplugins package.

Use View to zoom in and out of your image and to insert histograms. Using the Histogram option, you can judge the exposure of your image while viewing it.

Figure 19.5. Checking the Histogram

Checking the Histogram

Use the Image menu to edit the properties, comments and tags of your images and to apply basic effects or to insert text:

Apply Texture

Select the type of texture you want to apply to your image and determine how prominent this texture should be (Relief). digiKam applies the texture and saves the changes to the original copy of your image.

Add Border

Select the type of border. Depending on the type of border you have selected, choose one or two colors to be used for the border and set the width of the border around your image. digiKam creates the border and saves the changes to the original copy of your image.

Insert Text

Enter the text you want to superimpose on the image, choose font, font style and size. Select the text justification and decide whether the text should be rotated and to what degree. Add an optional border and semi-transparency. digiKam adds your text layer to the original image.

19.8.1. Fixing and Tweaking Your Images

Use the Fix menu to address a number of common defects related to digital imagery:

Colors

Tweak various aspects of the image related to colors.

Blur/Sharpen

Tweak the sharpness of your image or smooth it.

Unsharp Mask

Enhance the sharpness of your image.

Refocus

Sharpen your image by trying to refocus it.

Red Eye Reduction

Reduce or eliminate red eyes caused by use of a flash.

Inpainting

Heal” defective areas of your image.

Hot Pixel Correction

Detect and erase problem pixels of your image caused by defective pixels of your camera's sensor.

Restoration

Provides an all-inclusive treatment to images suffering from all sorts of digital defects, such as noise and scratches.

Noise Reduction

Remove artifacts, such as those caused by dust on your lens or sensor. Compensate for pixel noise caused by high ISO settings of your digital camera and reduce noise and artifacts in low quality scans.

Lens Distortion Correction

Compensate for barrel and pincushion distortion of your images caused by the use of strong wide-angle or telephoto lenses.

Anti Vignetting

Compensates circular shades (vignettes) at the edges or in the center of your image that were caused by the use of strong wide-angle or telephoto lenses.

To observe the functionality of the Fix options, look at Inpainting, for example. Assume some dust or scratch on your lens ruined an image. To remove this kind of artifact, proceed as follows:

  1. Open your image.

  2. Use the mouse cursor to select the area to which to apply the fix.

  3. Select Fix+Inpainting or press Shift-I.

  4. Determine the method to use to remove the artifact:

    • Choose one of the preset options (Remove Small Artifact, Remove Medium Artifact, or Remove Large Artifact) and proceed with Step 6.

    • Set the filter parameters on your own. Proceed with Step 5.

  5. If you opted against using any of the preset filters (in the Preset tab), open the Smoothing and Advanced Settings tabs and adjust the settings to your needs.

  6. Click OK to apply your settings and modify the image accordingly.

    [Tip]Creating and Reusing Your Own Filter Settings

    If you need to use the same set of settings more than once, for example, if a scratch on the lens ruined an entire series of images, create your set of filter settings. Save them for later use by clicking Save As and saving them to a text file. For subsequent images, open the Image Inpainting dialog, click Load, then select the text file and apply the filter settings with OK.

Figure 19.6. Using Inpainting to Remove Artifacts

Using Inpainting to Remove Artifacts

19.8.2. Applying Image Transformations

To scale or rotate an image, use the Transform menu:

Rotate, Flip, Free Rotation

Rotate your image to a certain degree. Rotate rotates by multiples of 90 degrees. With Free Rotation, specify any angle you want.

Crop, Aspect Ratio Crop

Crop your image. Crop cuts to any rectangular selection on top of your image. Aspect Ratio Crop crops the image following various sophisticated design principles.

Perspective Adjustment

Adjust the perspective of an image. For example, if you notice some odd angles in shots containing vertical or horizontal lines, use this tool to set them right. Grab any of the four handles to the corners of your image and move them as much as needed. Use the Crop tool to remove the resulting black edges of your image and to trim it down.

Shear

Shift one part of your image to one direction and the other to the opposite direction, either horizontally or vertically. Specify the angles for vertical and horizontal shear and use Crop to trim the resulting image.

Resize, Blowup

Scale your image larger or smaller. Resize offers a simple interface allowing you to manipulate your image size by pixel or percentage. Select whether to keep the aspect ratio. Blowup performs basically the same resizing operation on your image. In addition to a simple scaling operation, you can enable filters to apply to the scaled image to improve the quality of the resulting image. Whenever you need to print the final result, select Blowup instead for a simple Resize. You can save the filter settings to a text file and load and apply them to more images later.

Assuming you have an image that is otherwise perfect, but you are not entirely satisfied with the composition yet or need to crop your image to match a certain paper format for reproduction. In this case, use Aspect Ratio Crop and proceed as follows:

  1. Open your image.

  2. Select Transform+Aspect Ratio Crop.

  3. Determine the orientation and aspect ratio to use:

    None

    Specify a free crop of the image using the X, Width, and Y, Height sliders.

    Custom

    Select a custom ration of width versus height instead of using one of the preset values.

    X:Y Ratio

    These ratios match most of the common paper sizes used to print photographs. Pick the one that suits your purpose best.

    Golden Ratio

    A ratio (1:1.618) that is traditionally used by artists and architects to create harmonious results.

    Use Max. Ratio to set the crop area to the maximum possible size of the ratio specified.

  4. After determining the size of your crop selection, optionally apply compositional rules to it. The Composition Guide helps to create a crop selection that results in a visually pleasing image. Dotted lines are displayed that guide you to a better composition of your image.

    [Tip]For More Information

    For a comprehensive description of the options, refer to http://docs.kde.org/development/en/extragear-graphics/digikam/using-kapp-imageeditor.html.

  5. If the position of your crop does not follow the compositional rule to your satisfaction, move it.

  6. Click OK to apply your crop selection and trim your image.

Figure 19.7. Creating a Custom Crop Using Aspect Ratio Crop

Creating a Custom Crop Using Aspect Ratio Crop

19.8.3. Applying Filters and Effects

You can select from a variety of basic effects and filters to apply to your images to give them a more artistic or over-the-top look:

Black & White

Transform your color image into a black and white one. Choose Neutral Black & White to get a simple grayscale image. Simulate the use of a color filter (green, orange, red, or yellow) that accentuates areas of a certain color in the original image by selecting any of the Black & White with … Filter options. Simulate the tint effect of various chemicals in the dark room by selecting one of the Black & White with … Tone options.

Raindrops

Apply raindrop effects to your image. Determine the size and number of the drops and finally specify the degree of distortion caused by the drops (Fish eyes).

Infrared Film

Simulate the use of infrared film to achieve a slightly surreal effect. The result is strikingly different from the original image. Add additional film grain and tweak the sensitivity (ISO) to achieve a more artistic feel.

Oil Paint

Simulate an oil painting. Determine the brush size and the degree of smoothing to apply to your image.

Emboss

Pretend your image had been embossed to a sheet of paper. Choose an appropriate depth.

Solarize Image

Simulate an overexposure to sunlight.

Distortion Effects

Apply various strange distortion effects, such as fish eyes, to your image. Determine type, level, and repetition.

Add Film Grain

Add film grain to your image to give it a rough look.

Blur Effects

Blur your image to simulate the image being out of focus or to mimic any kind of movement that was not there when you took the image.

Charcoal Drawing

Transform your image into a black and white charcoal drawing. Choose an appropriate pencil size and determine the degree of smoothing to apply to the image.

Figure 19.8. Simulating IR Photography

Simulating IR Photography