We’ve all seen the effect where strange lines or colours appear in digital images. It’s called moiré, and it usually occurs in material or surfaces with fine lines. The reason for its appearance has to do with the frequency of the lines compared with the pixel count on a camera’s sensor. If the lines closely match the width of a pixel (or exactly match the width of a group of pixels) then you get moiré. It’s hard to remove completely but Lightroom’s Adjustment Brush can help. Paint with the Brush, then use the Moiré slider to tone down the colour pattern.