Improvement in image contrast after removal of stray light. Top: sunspot in NOAA AR 10944. The white contour refers to the umbral area chosen for analysis. The dotted white box represents a selected field of view shown in Figure 4. Middle: magnified view of umbra before stray light correction. Bottom: stray light corrected image. The images in the middle and bottom panels have been scaled identically. The white dashed circles enclose short filaments that are described in Section 3.1.