`   == What is DPI dependent on? ==  ``The DPI measurement of a printer is dependent upon several factors, including the method by which ink is applied, the quality of the printer components, and the quality of the ink and paper used.``  This is not true, or at least is confusing.  The DPI in the printing direction is dependent on the head firing frequency and the linear print speed. The DPI in the advance direction (perpendicular to the printing direction) is dependent on the spacing of actuators (e.g. nozzles for inkjet) on a head, and the angle of the heads. Each of these can be multiplied by use of interleaving/``weaving`` using multiple passes and/or multiple heads.  What the original sentence may have been trying to get at is that different print modes can use different firing frequencies, linear speeds, interleaving factors, etc., and the effect of ink and media settings in print drivers is often to change the print mode (possibly in addition to other software settings that don't affect DPI). Also, different print head technologies may improve at different rates in terms of firing frequency, actuator spacing, etc.  On the subject of advertisements, I strongly suspect that some of the dpi figures quoted in printer adverts are inflated. You can inflate a dpi figure by:  - counting different colors as more than one dot (this may be what ``4800 x 1200 color dpi`` means  I expect it is really 1200 x 1200 in 4 colors)  - counting each dot printed by a variable-dot head as more than one dot  - saying ``equivalent dpi`` and making up a random number.  This kind of creative arithmetic is all the result of trying to munge various resolution and quality factors into a single number for marketing purposes. It's similar to how clock speed used to be used to indicate how ``fast`` a processor was. At its worst, it can lead to distorted technical decisions that maximize DPI with no improvement in, or even at the expense of quality (just as the Pentium 4 design was distorted to maximize clock speed).  It's unlikely that someone could see a visible improvement in resolution above about 1000 dpi with the unaided eye at a normal reading distance. The extra quality that you can get from a higher dpi than that is not due to an increase in resolution; it's due to a reduction in ``graininess`` (and possibly better hiding of head defects) from using smaller drop volumes, which requires you to use more dots in a given space to achieve the same ink density.  To meaningfully compare printers, you need at the very least to know the volume of ink in a drop (for inkjet heads as of 2006, this can vary from about 2 to 80 picolitres), including what ``subdrop`` volumes are possible in the case of variable-dot heads, as well as the real dpi figure in each direction. The overall quality will also depend on halftoning algorithms, the gamut of the inks used, color management, positioning accuracy of the printer mechanism and any encoders, head defects and how well the print mode hides them, etc. The intended application is also significant: to give an extreme example, there's no point in achieving ``photographic`` resolution in a printer that will be used to print billboards  although color gamut would still be very important for the latter.    (employed by, but not speaking for, a printer manufacturer)`