The size of any digital image is solely determined by the pixel dimensions of the ﬁle which is totally independent of the resolution setting.
Resolution is only important when you are printing or outputting an image. To explain, a 3000 pixel image printed at 300ppi would be 10" while the same 3000 pixel image printed at 100ppi would be 30" in length.
You can change the images resolution settings in the Image Size dialog box in Photoshop and if you unlink it from the width and height dimensions and you'll notice that the pixel dimension of the image doesn't change when you vary the resolution.
Related: See all the textures in the Photomorphis Texture Store.