Microsoft yesterday released a series of fixes to its Surface Pro 4 and Surface Book Touch and Pen drivers that appear to have resolved a long-standing problem with pen stroke tapering and smoothing.
The issue was first reported by Brad Colbow in November and I reported about it here. Brad started a thread on the answers.microsoft.com site detailing his findings and Microsoft responded November 25 that it was aware of the problem and working on a fix. That thread had since grown to over 9000 views without a further update or resolution until yesterday.
After installing the driver updates, which include firmware fixes that require restarting the machine, the easiest way to see the stroke improvement is in the Surface app (below). The aliasing or stairstepping visible in Brad's tests are now properly smoothed.
I did a quick test in Photoshop CC 2015.5, the software that most suffered from the smoothing issue, and it appears to be working well now. As I test the Surface Pro 4 and Surface Book with other software, I'll update this post if necessary. In the meantime, if you encounter any remaining issues with strokes, please leave a comment below.
For more information about the July 14 drivers and to see the entire Surface Pro 4 update history, visit https://www.microsoft.com/surface/en-us/support/install-update-activate/surface-pro-4-update-history