tiff export problem

[Josè Campoy.]

I don´t know if it´s me and not the program

i have an image made with 3ds max the file size is 3000 X 2250 pix at 300 dpi.

y edit the contrast with photoshop and i save the file (still same res).

i and need to add a tree, i add the tree ans its shadow with xara, but when i try to export the .tiff file.

first i can´t save the alpha channel. and i choose 300 dpi and the file size is now more than 10 000 pix.

How can i export the file at the same size as original?.

under xxp 3.2

[Josè Campoy.]

done!, the problem was not the software.

Just reduce the image at around 30% annd export as 300 dpi, and i save the alpha chanel in a png file.
I forgot the psd export.