Technically photoshop invents (adds) or subtracts pixels from your photo; this usually involves an increase in the size of the file or. Respectively. A decrease in it. We talk about upward resampling when we increase the density.from 72 ppi to 300 ppi for example; instead we talk. About downward resampling when we. Subtract pixels by r ucing their relative density. Resampling. To resample a photo in photoshop just go to the image>image size menu menu-image. Size-image-photoshop in the dialog box you. Will see a “ resolution ” field express in pixels per inch.