Basic Effects

Basic Effects

Provides a dialog with some basic effects, common to most image editors.

User filter

This is a mathematical transformation which is applied to the image pixel by pixel. The center value of the matrix designates the pixel (anchor), while the surrounding values are included in the mathematical calculation.        

Morphing

Morphing uses a similar mathematical procedure to remove some details in the image, while accentuating others. The size of the matrix and the number of pixels to be combined are determined by the Window Size.        

Add Borders & Shadows

If you add a shadow to the image, you are also adding a transparent area around the image. Transparency can only be stored in image filetypes which contain an Alpha Channel, like PNG. If you store the file as JPG, you will be asked for a color replacement, where you would usually pick White.

Invert Colors

This feature can come in handy, if you scanned color negatives, i.e. where the colors are inverted.

Convert to Sepia

This feature is similar to the Duotone Image of the Advanced Effects, when using a blend of yellow.

Convert to B/W

An alternative to this shortcut is the Color > HSL toolpanel, where you would set Saturation to 0.

Define Transparent Color

There are several ways to define transparent areas in an image. The transparency tool works best with objects, that have a bounding frame with a distinct color. However, setting this color to transparent would also include areas of the object having the same or similar color (example 2). To overcome this, you would select the object, invert the selection, and use the transparency tool on this inverted selection only (example 3).

A more flexible method is using the Paint or Fill brushes with a transparent color, allowing for more options, like the Inclusive fill mode (example 4). Read about the identical Magic Wand Modes to understand this option. The transparency tool only works in Global mode.

Careful: JPG files don't have an Alpha Channel, so you would have to save the image to a PNG file instead.

Remove Alpha Channel

Does the opposite of the transparency tool above, i.e. removes transparency in an image and asks for a Replacement Color. Transparency is stored in the Alpha Channel of an image.

Remove a Color (Washout)

This tool opens the Color toolpanel in HSL mode and asks you to use the Pipette to select a source color. This color can then be reduced to grayscale by moving the Saturation slider to a value below 0. The washout tool can be used for so-called Colorkey effects, i.e. to enhance objects while blending out the background. It can also help you to remove unwanted Color Stains or to shift color ranges.

Replace a Color

Correct Perspective

Radial Stretch (correct lens distortion)

Radial Stretch uses a mathematical matrix transformation to correct lens distortion. Usually you need to move the sliders only a couple of ticks up or down. Higher values can be used to create a fisheye effect.

Deskew

Deskew uses an intelligent image recognition algorithm to detect horizons in images and automatically correct minor rotations. The algorithm does not work for all images, but the results for scanned text documents are the more better, as required in preparation of OCR. This is why the option is also available in the Scan dialog.

If you want to determine a horizon manually, use the Rotation dialog instead.

Separate Images

Automatic separation of images can become useful for multiple photo scans. Make sure the photos are not overlapped when placed on the scanner. The function tries to detect distinct photos in the scan, which are then automatically separated and rotated.

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