Image resolution

Screengrab doesn't cut it for seismic (or most other things), especially if you save as a JPG (see image formats).

Forget dpi
It is very common to be asked for a certain number of dots per inch, or dpi (which should really be ppi, or pixels per inch). For example, I've been asked by journal editors for images 'at least 200 dpi'. However, image files do not have an inherent resolution — they only have pixels. The resolution depends on the reproduction size. So, if your image is 800 pixels wide, and will be reproduced in a 2-inch-wide column of print, then the final image is 400 dpi, and adequate for any purpose. The same image, however, will look a little grainy at 4 dpi on a 16-foot-wide projection screen.

Rule of thumb: for a computer screen or projector, aim for enough pixels to give about 100 pixels per display inch. For print purposes, aim for about 300 pixels per inch. If it really matters, or your printer is especially good, you might be safer with 600 pixels per inch.