A previous Instructable showed how to measure the horizontal resolution of Ember 3D prints. That resolution is ultimately limited by the size and spacing of the mirrors in Ember's DMD and the filtering applied to the image of each slice to convert them to the DMD's diamond pixel array. The focus of the projected slice images, the properties of the resin, and the settings (e.g. exposure) that control the printing process may further limit resolution. While the number of distinct line pairs per mm that can be printed cannot be increased beyond these fundamental limits, it is possible to represent some features with greater detail than these limits might otherwise suggest.
In the field of lithography, e.g. for semiconductor manufacturing, a variety of such resolution enhancement techniques are used. One of the most well known is Optical Proximity Correction (OPC). In this Instructable we'll see how OPC may be used to improve the fidelity with which fine details may be printed. While printed text is used as an example here, the same technique could be applied in any case where it was desired to make the corners of printed objects sharper.
The image above left (in blue) shows how an L-shaped lithographic mask (top) leads to a printed image (bottom) in which the corners are rounder and the lines are shorter than in the mask, due to optical proximity effects. On the right (in green) it shows how adding "serifs" and cutouts to correct the mask leads to a printed image that better represents the original desired shape. Thus OPC provides a way to compensate for errors introduced in the lithographic process, regardless of their specific causes.
While OPC may be applied manually, as in this Instructable, there are also algorithms that may be used to automate the correction process. See Fast Optical and Process Proximity Correction Algorithms for Integrated Circuit Manufacturing, for a good discussion of those techniques.