You know what is the effect barrel, or cushion effect, photographic?
One of the filters node editor simulating image distortions produced by the lens of a camera and other optical elements is “Lens Distortion“.
The distortions can affect both the way the colors in the image.
Among the most common we:
- Pincushion: Is produced with large angular. The straight lines are curved (eg buildings) towards the outside of the image.
- Cushion distortion: Similar to barrel distortion, but deformation or bending occurs to the inside of the image.
- Chromatic aberration: It is an effect that causes objects present images colored borders.
To understand the above cases depart from a sample image magnifying modify the specific effect.
The image is composed of simple horizontal and vertical lines intertwined.
To be as simple, will allow us to easily see changes.
The effects of barrel and cushion are opposites, affect curving in opposite directions to the image.
The effect is sharply at the edges.
Chromatic aberration behaves like a light diffraction, separating your colors.
Visually appreciate a displacement of the color components of each line, horizontally in the example.
The angle of displacement or aberration may change. In the example the vertical lines are affected by this vertical diffraction while not present.
Last, this filter can affect the sharpness of images, modifying its granularity.
Application of the filter in Blender
From the options find “Distort” that will display a new menu with distortion filters, among which we find the one we want in this case: “Lens Distortion”
- Distortion: The amount of distortion, ranging from -1.0 (cushion) can assert 0,0 (none) and reaches 1,0 (barrel).
- Dispersion: chromatic aberration, separating the RGB channels and smooth to the mixture to a stronger effect of the spectrum at the outer edges of the frame.
- Restlessness: Staggers random RGB channels, giving an effect of noise instead of a smooth mixture.
- Adjustment: Scales up the image to fit the frame, instead of leaving black areas around the corners (as a great fisheye lens)
- Projector: Disables the lens distortion and RGB channels overlap with a displacement on the horizontal axis, (as an uncalibrated projector). The dispersion value determined controls the channel spacing.