Overview

The pressure dead zone is an area of a pressure curve that is deliberately designed to ignore a bit of the lower end of the pressure range. The pressure dead zone effectively increases the IAF of the pen.

Visualization

Visually the pressure dead zone can be seen whenever the lower left corner of the pressure curve is displaced to the right

Uses

We often prize having extremely low initial activation force with our EMR pens because it makes them more sensitive to lighter strokes.

But that sensitivity comes at a cost. It can introduce several kinds of problems. And a pressure dead zone can address these problems

examples of problems that pressure dead zone could be applied to:

• drawing while hovering

• strokes having tails

Default dead zones in tablet drivers

When you look at the default pressure curve and a tablet driver for most of the EMR pens you will encounter, you will notice that they almost always do not have a dead zone predefined.

There are a couple of notable exceptions (as of 2025-03-18).

• The default pressure curve for the Wacom pro pen 2 (KP-504E) has a pressure dead zone

• The default pressure curve for the Huion PW600 pens also has a small pressure dead zone.

Testing results

I've tested 4 Wacom pro pen 2 units by using them without the default pressure dead zone. Of the four two did not have any drawing while hover problems. The other two did in fact draw while hovering. It appears that the Wacom pro pen 2 is a bit oversensitive and some units by default do draw on hover. So this explains why Wacom defaults to a small pressure dead zone for these pens. Note that the Wacom pro pen 3 does not have a default pressure dead zone.

For the Huion PW600 series of pens, without the pressure dead zone I did not encounter any drawing while hovering problems.

Recommendation

the pressure dead zone is intended to solve a problem. But not all pens have that problem. I would suggest that when you get a new tablet or a new pen you take a look at the tablet driver and verify whether a pressure dead zone is set by default.

If it is try using the pen without the pressure dead zone. And if you don't notice any problems then leave it that way. Because that will give you a more sensitive pen with a lower initial activation force.

Links

• 2025-03-18

Overview

Your pen senses pressure and encodes it as a number. You can think of the number as ranging from 0 to the maximum number of pressure levels of your pen. In many cases its easier to "normalize" this number so that it ranges from 0.0 to 1.0. This makes discussing the pressure easier to understand in many cases.

This number flows through a "Pipeline" of components: tablet firmware -> tablet driver -> OS pen subsystem-> pen-aware application -> brush engine

Some of these components can process the the pressure - that means they can alter the number - before it is sent to the next component.

The processing of the pressure number alters how the pen will feel to draw with.

There are different ways in which components can process the pressure number. These include:

• Pressure processing curves (also called just "pressure curves")

• Pressure smoothing

This document deals with pressure processing curves.

Response curve vs processing curve

Thinking of it as numbers:

• The pressure response curve is how the pen hardware handles pressure. It maps physical pressure into a pressure number.

• The processing curve is a mathematical operation that takes a pressure number and can change it into a different number.

Thinking of it as a behavior ("how the pen feels")

• The pressure response curve is the "native" behavior of how the pen feels to draw with.

• The pressure processing curve is a way of modifying that behavior.

What a pressure processing curve looks like

For example in the Wacom Tablet Properties app it looks like this:

• The X axis labelled as "Pen pressure" is the logical input pressure

• The Y axis labelled as "Output" is the output logical pressure

• This particular curve bends down a little. But many other shapes are possible. Each shape has their uses.

Popular coverage of pressure curves is misleading

You might encounter YouTube videos where people describe the pressure curve as the pressure behavior of the pen. This is completely inaccurate. The pressure curve describes how the pressure behavior (the pressure response) is being modified. You cannot look at a pressure curve and understand the pressure behavior of your pen. The only way for you to understand the pressure behavior of pen is to physically measure it with the scale and start mapping physical pressure values to logical pressure values.

Pressure curve shapes

There are a variety of pressure curve shapes - each of which can solve some problem or achieve some visual effect.

To see which drivers and apps support which shapes see this:

Things you can do with pressure curves

• - a curve that "does nothing"

Driver UX for pressure curves

See

Here are two examples of curves that ignore input.

IGNORE BOTTOM - ignores the lower end of logical pressure

IGNORE TOP - ignores the upper end of logical pressure

IGNORE BOTTOM

Effectively this increases the perceived IAF of the pen.

This is useful in several cases:

Introduction

The null pressure curve is the most important pressure curve - exactly because it does nothing. We can apply the null pressure curve to any pressure profile and it will not shift the profile in any direction.

Definition

The definition of a null profile is a pressure curve function that takes the input logical pressure and returns that very same value as the output logical pressure. In order words f(p) = p.

If you take the range of input logical pressures which range from zero to one and plot them on the X axis of a chart. And then you apply the null pressure curve to those values and plot the result of the function on the Y axis - then you get a straight line at 45° that goes from the lower left corner to the upper right corner of the chart.

Anytime you see a chart like this it clearly identifies that null pressure curve. And you can be sure that it does not do anything to a pressure response.

And the chart above you can see there's been no change because the orange line which represents the pressure response after applying the curve has exactly the same shape as the original pressure response.

null pressure curves are extremely useful.

We encounter pressure curves in tablet drivers and in creative applications. These kinds of applications often use the null pressure curve as the default value for any pressure curves they have. This isn't always true but it is a very common thing to see.

If you're ever trying to solve some problem with the pressure of your pen the knowing about the null pressure curve is useful. Because it might be that somehow your pressure curve was modified and is affecting your pen. So a very common troubleshooting tip is to make sure that your pressure curve has been reset back to the null pressure curve. This way you can be sure it is not affecting what is going on

Overview

Applications may offer pressure curves.

• Drawing applications - almost ALL have pressure curves.

• Note-taking applications - almost never have pressure curves.

Pressure curve shape support

Not all pressure curve shapes can are possible in all cases.

• Drivers usually offer only simple pressure curves

• Applications are generall very flexible

Overview

Typically, a pressure curve function takes input logical pressure values in the range of [0,1] and maps it to values in an output range of [0,1]. This means that the full output range is used.

Some curves can limit their output range to achieve better control over brush strokes.

Visual interpretation

The easy way to tell that a pressure cuve constrains the output range is to notice that the curve shape does not reach to the bottom or to the top of the pressure curve graph. Two examples are below.

Misc notes: Wacom pressure deadzone

Some of Wacom's Pro Pens are so sensitive, Wacom by default configures pen pressure curve in the driver to have a small "deadzone" at the lowe end of pressure. This means the very lowest pressure readings are ignored.

Here is a screenshot showing that pressure deadzone in the default pressure curve the Wacom driver uses for the Wacom Pro Pen 2 (KP-504E)

Resources

Overview

Tablet drivers offer a UX to see and modify pen pressure curves. Below you'll see how to access this UX in various tablet drivers.