Fine-scale features in the straight part of the eastern ribbon as outlined by the cyan rectangle in Fig. 3e. Upper row: CRISP images in the Ca II 8542 Å and Hα red wings. Bottom row: Colour maps computed by subtracting the wing intensities at the spectral positions shown in the titles. Both colour maps are saturated symmetrically around 0 so that pixels in white show no excess emission in either red or blue. Cyan contours in all panels outline bright features from panel (a). Contours surrounding pixel (a)–(d) were detected by the FWHM method, while the contour surrounding pixel (e) was manually selected. The green pixels highlight the centre of the blobs and the magenta pixels are located in regions between the blobs. Pixel (f) is selected below the lower-most blob in a region where brightening is evident for Ca II 8542 Å and Hα. All pixels are labelled with a letter a–j that corresponds to the panel titles in Figs. 7 and 8.