We report on a photometric study of a sample of 22 disk galaxies in the Hubble Deep Field South NICMOS parallel field .
The redshift range of the galaxies is z = 0.5 - 2.6 .
We use deep NICMOS J and H band and STIS open mode images , taken as part of the HDF-S project , to construct rest-frame B -profiles and ( U - V ) color profiles of the galaxies .
Before fitting isophotes , images are deconvolved with PSF .
Derived surface brightness profiles are approximated by Sérsic luminosity distribution .
Significantly large population of disks can not be represented by an exponential disk , but this can be well done by Sérsic law , if n < 1 .
This might be the same phenomenon which has earlier been referred to as truncation of disks .
Parameter n does not vary significantly with redshift .
Galactic sizes decrease with redshift as r _ { e } ( z ) / r _ { e } ( 0 ) = 1 - 0.26 z .
The rest frame ( U - V ) color shows a clear decrease at z \approx 2 , concordantly with the understanding of more intense star formation at earlier epochs .
Color gradients \Delta ( U - V ) / \Delta r are small and roughly constant at z < 2 .
At z > 2 , dominantly positive gradients appear , possibly indicating centrally concentrated star-formation .
On the basis of ( U - V ) color and chemical evolution models , the disks observed at z \sim 2.5 have formed between z = 3.5 - 7 .
Scale radii r _ { e } of the galaxies correlate with the scale surface brightnesses \mu _ { e } for the sample .
None of the studied parameters shows clear dependence on absolute B luminosity for the galaxies .