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[Definition] Chromatic Aberration

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  • [Definition] Chromatic Aberration

    First of all, thanks to Alpage for bringing this to our attention and providing the description and correct word for it.

    A problem that can occur during the scanning process.

    I am used to seeing this type of defect with poor quality wide angle adaptors. It's called chromatic aberration and it's caused because different wavelengths of light are refracted differently. In the case of camera lenses the aberration is typically spherical and therefore is most severe at the edges of the frame where the light is bent at the greatest angle.
    Scanners may bend light through a prism rather than a spherical lens, so the aberration is 'linear'.
    Do a search on Google with keywords 'scanner' 'chromatic' and 'aberration' and you will see quite a few articles on the subject.
    This can be seen in the final scanned results as a color fringe that extends beyond the edge of the image. Example > Check out the scanned image for Restoration Challenge # 23
    You will see the redish edge at the top of the image and also the greenish tinge at the bottom. This is a misalignment of the color channels created during the scanning process