  We present a new method to photometrically delineate between various
sub-types of type Ia supernovae (SNe Ia). Using the color-stretch parameters,
$s_{BV}$ or $s_{gr}$, and the time of i-band primary maximum relative to the
B-band or g-band maximum it is demonstrated that 2003fg-like, 1991bg-like, and
2002cx-like SNe Ia can readily be identified. In the cases of these extreme SNe
Ia, their primary i-band maximum occurs after the time of the B or g band
maxima. We suggest that the timing of the i-band maximum can reveal the
physical state of the SN Ia explosion as it traces: i) the speed of the
recombination front of iron group elements in the ejecta, ii) the temperature
evolution and rate of adiabatic cooling in the ejecta and, iii) the presence of
interaction with a stellar envelope. This photometric sub-typing can be used in
conjunction with other SNe analysis, such as the Branch diagram, to examine the
physics and diversity of SNe Ia. The results here can also be used to screen
out non-Ia SNe from cosmological samples that do not have complete
spectroscopic typing. Finally, as future surveys like LSST create large
databases of light curves of many objects this photometric identification can
be used to readily identify and study the rates and bulk properties of peculiar
SNe Ia.
