4.7. IWarp
| 4. Distort Filters |

### 4.7. IWarp

#### 4.7.1. Overview

Figure 16.45. Applying example for the IWarp filter

Original image

Filter “IWarp” applied

This filter allows you to deform interactively some parts of the image and, thanks to its Animate option, to create the elements of a fade in/fade out animation between the original image and the deformed one, that you can play and use in a Web page.

To use it, first select a deform type then click on the Preview and drag the mouse pointer.

#### 4.7.2. Starting filter

You can find this filter through Filters → Distort → Iwarp.

#### 4.7.3. Options

The options of this filter are so numerous that they come in two tabs. The first tab contains general options. The second tab holds animation options.

Settings

  Figure 16.46. “IWarp” filter options (Settings tab)

  The Settings tab allows you to set parameters which will affect the preview you are working on. So, you can apply different deform modes to different parts of the preview.

  Preview

    Here, the Preview is your work space: You click on the Preview and drag mouse pointer. The underlying part of image will be deformed according to the settings you have chosen. If your work is not convenient, press the Reset button.

  Deform Mode

    - Move: Allows you to stretch parts of the image.

    - Remove: This remove the distortion where you drag the mouse pointer, partially or completely. This allows you to avoid pressing Reset button, working on the whole image. Be careful when working on an animation: this option will affect one frame only.

    - Grow: This option inflates the pointed pattern.

    - Shrink: Self explanatory.

    - Swirl CCW : Create a vortex counter clockwise.

    - Swirl CW : Create a vortex clockwise.

  Deform Radius

    Defines the radius, in pixels (5-100), of the filter action circle around the pixel pointed by the mouse.

  Deform Amount

    Sets how much out of shape your image will be put (0.0-1.0).

  Bilinear

    This option smooths the IWarp effect.

  Adaptive Supersample

    This option renders a better image at the cost of increased calculation.

    Max Depth: this value limits the maximum sampling iterations performed on each pixel.

    Threshold: when the value difference between a pixel and the adjacent ones exceeds this threshold a new sampling iteration is performed on the pixel.

Animate

  Figure 16.47. “IWarp” filter options (Animation tab)

  This tab allows to generate several intermediate images between the original image and the final deformation of this image. You can play this animation thanks to the Playback plug-in.

  Number of Frames

    That's the number of images in your animation (2-100). These frames are stored as layers attached to your image. Use the XCF format when saving it.

  Reverse

    This option plays the animation backwards.

  Ping-Pong

    When the animation ends one way, it goes backwards.

4.6. Erase Every Other Row |  | 4.8. Lens Distortion