Pixel-by-pixel correlation between dust emission and atomic gas column density for field V1 and V2 in the IRAS, SPIRE, and Planck-HFI 850 μm bands. For the LVC (IVC) gas component, the dust surface brightness is corrected to exclude the fitted contribution of the IVC (LVC) component; also, the offset and ecliptic latitude component is removed. Contours of constant pixel density enclosing 99.9, 75, 50, and 25% of the pixels are plotted. The gray-scale filled contours show the same correlation after masking regions that are deviant from the model by more than 3σ_R at 250 μm. Solid and dashed lines show the fitted correlation before and after the masking, respectively. Small changes in the fitted O_ν before and after the masking result in slight displacements of the line and filled contours. Orange crosses in the 250 μm panels refer to pixels within the isophotal ellipses of object 6 (in V1) and 14 (in V2). Magenta circles in the V2 250 μm panels show the region “N” of negative residuals (see Sect. 6 for details).