Chromatic aberration: Remove chromatic aberrations without losing any detail

What is chromatic aberration?

Chromatic aberrations appear as red or purple outlines. They are especially visible in areas with strong contrasts. This phenomenon occurs when the lens is unable to converge all the colors in the same point. The amount of chromatic aberrations in a photo depends on the type of lens used as well as other parameters, including the aperture value, focal length, and focal distance.

What types of chromatic aberrations exist?

There are two types of chromatic aberration. The first is lateral — or transverse — chromatic aberration. This occurs when different light wavelengths are focused at different positions on the surface of a camera’s imaging sensor. The second type of chromatic aberration is called longitudinal — or axial — aberration. This is when the different wavelengths of colored light are focused at different distances from the surface of the camera’s sensor.

What Causes chromatic aberration in photos?

White light is made up of a full spectrum of colors, as seen in a rainbow or when light is split through a prism. Each different color has a different wavelength and focuses at a slightly different distance.

Most lenses make a pretty good job of bringing the different colors to focus at roughly the same point, but sometimes, especially towards the edge of an image where there are strong transitions between light and dark, chromatic aberrations can appear as red or purple fringing.

A separate analysis for each chromatic channel

To assess the lateral chromatic aberrations in a lens, images of a dot plot are taken with different focal lengths and distances. At different points in the field, DxO’s experts calculate the maximum distance in pixels between the different color components (red, green, and blue) of the same point.

The resulting measurement makes it possible to establish a maximum chromatic aberration value according to a precise scale. When the value is under 0.03 mm, it is not perceptible. Between 0.03 and 0.06 mm, it is visible. When the value is over 0.07 mm, it becomes problematic.

How does DxO correct chromatic aberration?

DxO algorithms correct chromatic aberrations by aligning geometric positions in the scene being photographed with each color.

Because chromatic aberrations vary depending on the focal length and distance, DxO algorithms take into account these two influential parameters to more effectively correct chromatic aberrations in RAW and JPEG images. As a result, the software removes colored outlines without degrading the photo’s color and detail.

Discover camera and lens corrections with DxO PureRAW  ³ and DxO PhotoLab ⁶