Interestingly, viewers are mostly disturbed if they see a photo with converging lines that they know or assume to be vertical in reality. Parallel lines are an essential feature of most types of architecture when photographed at an angle parallel lines get transformed into converging lines that meet at some vantage point within or outside the image frame. Note the converging lines of the vertical architectural features.Ĭonverging lines are a special case of perspective distortions frequently seen in architecture photographs. Taken with 14mm (APS-C) the two sculptures cover different areas in the image although they have the same size. Once again this is not an effect of the lens but an effect of the perspective (distance) of the viewer or camera to the scene. As lenses with a short focal length force you to get closer to your subject, photos taken with wide angle lenses are more prone to show strong perspective distortions than telephoto lenses. The closer you get to a subject the stronger the effect. Perspective distortions cause objects close to the viewer to appear much larger than objects further away in the background. As such they are not to be confused with lens errors which can be corrected in darktable’s lens correction module. Perspective distortions are a natural effect when projecting a three dimensional scene onto a two dimensional plane photographically. The GUI of the perspective correction module. The underlying mechanism is inspired by the program ShiftN developed by Marcus Hebel and published under the GPL. To overcome these limitations a new “perspective correction” module has just been added that is able to automatically correct for converging lines. Although the principle is simple and straightforward, there are cases where it can prove difficult to get a convincing correction, especially if no distinct vertical or horizontal features can be spotted in the image.
#Darktable lens correction manual
Since many years darktable offers a versatile tool for manual perspective correction in the crop & rotate module.
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