We present corrections for the change in the apparent scalelengths , central surface brightnesses and axis ratios due to the presence of dust in pure disk galaxies , as a function of inclination , central face-on opacity in the B-band ( { \tau } ^ { f } _ { B } ) and wavelength .
The correction factors were derived from simulated images of disk galaxies created using geometries for stars and dust which can reproduce the entire spectral energy distribution from the ultraviolet ( UV ) to the Far-infrared ( FIR ) /submillimeter ( submm ) and can also account for the observed surface-brightness distributions in both the optical/Near-infrared and FIR/submm .
We found that dust can significantly affect both the scalelength and central surface brightness , inducing variations in the apparent to intrinsic quantities of up to 50 \% in scalelength and up to 1.5 magnitudes in central surface brightness .
We also identified some astrophysical effects for which , although the absolute effect of dust is non-negligible , the predicted variation over a likely range in opacity is relatively small , such that an exact knowledge of opacity is not needed .
Thus , for a galaxy at a typical inclination of 37 ^ { \circ } and having any { \tau } ^ { f } _ { B } > 2 , the effect of dust is to increase the scalelength in B relative to that in I by a factor of 1.12 \pm 0.02 and to change the B-I central colour by 0.36 \pm 0.05 magnitudes .
Finally we use the model to analyse the observed scalelength ratios between B and I for a sample of disk-dominated spiral galaxies , finding that the tendency for apparent scalelength to increase with decreasing wavelength is primarily due to the effects of dust .