Efx Chromatic Aberration

Posted By admin On 25/11/21
  • EFX Chromatic Aberration. This plugin lets you apply (or remove) the chromatic aberration effect to a layer. Compatibility After Effects; Pubes. Spline generator along the edge of the shape or inside the polygon.
  • CHROMATIC ABERRATION A simulated lens distortion effect that mimics real-world lens aberration, in which there is a failure of a lens to focus all colors to the same convergence point. This effect includes color splitting, lens distortion, blurs and lens textures for added realism.
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In optics, chromatic aberration (CA), also called chromatic distortion and spherochromatism, is a failure of a lens to focus all colors to the same point. It is caused by dispersion: the refractive index of the lens elements varies with the wavelength of light.

Chromatic aberration is an issue that arises from the inability of a lens to focus all colors in the same place. This happens because the focal length (the distance between the lens and the image sensor when the subject is in focus) depends on a property called refraction, which is the bending of a wave when it enters a medium where its speed is different. Since blue and red light have different indexes of refraction, their focal length is also slightly different. Chromatic aberration is clearly visible on photographs or video as the color channels are not perfectly aligned.

Chromatic Aberration in Virtual Reality

When chromatic aberration occurs in virtual reality, a viewer faces two issues. On one hand, the simple presence of this optical distortion can break the suspension of disbelieve as it serves as a constant reminder of the artificial nature of the virtual environment. On the other hand, it can lead to discomfort and headaches that could make longer VR sessions impossible.[1]

Software Correction for Chromatic Aberration

Fixing chromatic aberration in software is usually done by applying the classic 'Brown's model' distortion correction formula to each color channel independently, using slightly different distortion coefficients for each color channel, thus changing the red, green and blue color channel to a different scale.

The drawback of these methods is that they lead to a loss in image quality. For increased accuracy, a subpixel offset has to be taken into account for the different color channels.[2] A correct use of subpixel interpolation enables developers to effectively reduce chromatic aberration below noticeable levels.

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Hardware Correction for Chromatic Aberration

Chromatic aberration can be minimized by using an achromatic lens. This type of lens is usually composed of two individual lenses made from glasses with different amounts of dispersion. The use of a strong positive lens made from a low dispersion glass like crown glass coupled with a weaker high dispersion glass like flint glass can correct the chromatic aberration for two colors, e.g., red and blue.[3]

References

  1. http://blog.qwrt.de/improved-pre-warping-for-wide-angle-hmds/
  2. https://forums.oculus.com/viewtopic.php?t=32
  3. http://hyperphysics.phy-astr.gsu.edu/hbase/geoopt/aber2.html
Chromatic

Efx chromatic aberration mac
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03 White vignette

Next, I’m using Silver Efex Pro’s vignette tools to tone down the background. Most vignettes are dark, but this time I’m using a white vignette to fade out the background towards the edges. I’ve set the Amount value to maximum, adjusted the Circle-Rectangle slider so that the vignette has a slightly square shape, then set the Size slider so that Charlotte’s face is unaffected, but the background fades out progressively.

04 Selenium toner

Efx Chromatic Aberration

I did do one more thing. Many black and white pictures do benefit from a toning effect – it gives them a richness and a depth that simply greyscale images don’t always have. Toner effects generated in other programs can be just too crude, but Silver Efex Pro’s are so subtle that on their weakest setting you hardly notice them – you get a subtle extra ‘depth’ without really realising where it’s come from.

It’s tempting to head straight for the sepia effects section when you’re toning a black and white picture, but I think a subtle blue Selenium toner effect works better here.

05 The finished portrait

This picture is a long way from the one I started with, and I think it shows the benefits of Silver Efex Pro compared to trying to work out how to do it manually in a program like Photoshop. The tonal adjustments have proved much more effective, the vignette effect proved easy to apply and I really like the depth and subtlety of the selenium toner effect.

Efx Chromatic Aberration Mac

See also

More Silver Efex Pro tutorials

Efx Chromatic Aberration

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