NY nonresident wage allocation for income earned outside of NY

I live in NJ, and work in primarily in NY and understand I have to pay NY income taxes as a nonresident.

 

My job occasionally requires travel outside of NY.

My W2 shows the income amounts earned in each of these states along with the corresponding state tax withholdings. 

The NY income amount of course still matches my federal taxable amount and there fore includes the amounts earned outside of NY.

 

When completing the NY nonresident form, can I adjust my NY income to account for the income (from my NY job) that was earned outside of NY?

Or does NY require that I pay tax on the full income?