Tweaking Pressure Sensitivity beyond Wacom's allowed settings

Discussion in 'Software' started by thatcomicsguy, Oct 5, 2009.

  1. thatcomicsguy

    thatcomicsguy Scribbler - Standard Member Senior Member

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    Hi all!

    This may have been covered in the past, but after spending an hour searching about and finding nothing here, I thought the subject was worth a fresh new thread. . .

    After a few months and hundreds of hours of dutiful drawing on my handy-dandy Portege M200, (awesome art tool!), my hand-eye-stylus awareness (for lack of a better term), is now pretty sharp, and I've been finding that the standard Wacom driver doesn't offer the kind of fine-tuning I want with regard to pressure sensitivity.

    And so, after digging around I found the following website which offered some instructions on how to get into the guts of the Wacom settings and tweak it to my own personal satisfaction. (As opposed to that of the Wacom engineering staff.)

    You can look at the original website. . .

    http://junkyardsam.blogspot.com/2009/02/wacom-cintiq-driver-manual-adjustment.html

    I'll repeat and adjust the relevant steps here. . . (The fellow who posted was doing so for a Cintiq. It's a little different for a Tablet PC)

    --The following steps assume that you have the latest Wacom driver for Tablet PCs installed on your system enabling pen pressure support.


    1. Open up the Wacom Properties window from the control panel or start menu, set the pressure sensitivity slider to the middle and close the panel again. This isn't vital, but it puts you on the same page as these instructions. The Wacom Properties window needs to be closed for the next steps to work.

    2. Go to Settings > Control Panel > Adminstrative Tools > Services. Highlight TabletServicePen, right-click and STOP the service.

    --This turns off your pen, so you'll need a mouse plugged in to continue navigation. The reason you turn this off is so that you can edit the Wacom driver settings while they are not engaged. You'll turn them back on after you're done tinkering, so keep the Services window open.


    3. Navigate to the Pen_Tablet.dat file. . .

    C:\Documents and Settings\Administrator\Application Data\WTablet\Pen_Tablet.dat

    It may be in a different place depending on how you have your version of Windows set up, but you'll find it eventually because if you have the Wacom driver installed, then it's there someplace. Also, you'll need to set Windows so that hidden files are visible. It might be a good idea to back up this file in case things go horribly wrong, though Wacom's driver will generate it again automatically, so it's no biggie. It IS handy to have a copy with the settings all at the base line for handy reference while you're doing this next part. . .


    4. Open up the Pen_Tablet.dat file in a text editor. Scroll down to the following line. . . (It's within the first 50 lines of the document).

    "PressureCurveControlPoint 20 0 127 127 254 254"

    (If you followed step 1, then the numbers you find will match those above.)

    --If your stylus has an eraser, then you'll see this same line appear twice, (perhaps with different numbers). You need the second one. The first refers to the Eraser button. The way you know this is that the line five up reads, ButtonName tip (As opposed to ButtonName eraser)


    5. The numbers. . .

    There are three pairs representing the bottom, middle and top of the pressure curve. Here's what they mean. . .

    20 0 = You have to apply 21 units of pressure to the nib to get an output of 1. Anything less and the Tablet registers a zero output. It's best to leave a bit of a buffer like this so as to avoid un-intended clicks. Wacom's default settings on this end of the curve seem to work well.

    127 127 = This is the middle of the pressure curve. You apply 127 units of pressure to get an output of 127.

    256 256 = This is the top of the pressure curve. You apply 256 units of pressure to get an output of 256.

    Pretty simple. Now you know enough to experiment. --My current preferred pressure settings are the following. . .

    "PressureCurveControlPoint 38 0 200 70 254 254"

    This simulates a nice firm nib but with a little more flex to it than the Wacom Properties menu allows for, as well as a faster drop off when I lift my hand, (preventing too-long 'ink' trails).

    --I also changed the two lines ahead of this setting to the following figures...

    "UpperPressureThreshold 38"
    "LowerPressureThreshold 36"

    I'm not entirely clear as to what these do, but it's what the Wacom driver automatically sets them at when its native pressure adjustment bar in the Wacom Preferences window is set to one space from the maximum, (where I normally worked at before I started tinkering), so I felt I shouldn't argue too much with it. Perhaps somebody has a little more insight into what these numbers do.

    In any case, none of these settings appear to be mission-critical; meaning, you can tinker with them with no fear of crashing your computer. Your pen will simply act funny. Restarting the Wacom driver and pulling the pressure slider left or right will reset everything to the default values. It's all reasonably fool-proof.

    6. Save the Pen_Tablet.dat file with your changes and re-start TabletServicePen in the Services window. Then re-start Photoshop (if you're using that program for your drawing), to have the changes take effect. Then test out the responsiveness of your stylus. If you want to make further changes, just turn off TabletServicePen again, and head back to your text editor.​

    That's it!

    I hope this has been useful to those of you who haven't already figured this stuff out. It has allowed a more snug fit with my personal style of drawing.

    Cheers!
     
    Last edited by a moderator: May 16, 2015
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  2. HellParker

    HellParker Civil Engineer

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    great work, have you some advice to get more acurate pen calibration??
     
  3. thatcomicsguy

    thatcomicsguy Scribbler - Standard Member Senior Member

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    Hm. I'm assuming you mean the x,y coordinate calibration. --I've found that the basic driver works well enough for me in this regard.

    I did however run across a page in my hunting which dug pretty deeply into the specifics of that element of the Tablet PC Wacom digitizer system. I was looking at it through the Google translator, (from Japanese), so it wasn't an easy read, and it wasn't what I was after at the time, but it looked pretty interesting and (fairly complicated). The author had graphics up explaining how the driver interpreted the various analog EM regions of the digitizer and what values in the software affected the signal the computer worked with. You could probably do a lot of manual adjustment if you wanted.

    So I spent twenty minutes scouring my web history trying to find that page again, but was unable to do so. Sorry. But it IS out there if you want to hunt for it.

    Good luck!
     
  4. kritzler

    kritzler Pen Pal - Newbie

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    Cool and interesting find, thank you!
     
  5. thatcomicsguy

    thatcomicsguy Scribbler - Standard Member Senior Member

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    Turns out I had bookmarked that page on another computer.

    http://translate.google.ca/translat...q=wacom+systemnonlinearsensitivity&hl=en&sa=G

    --It's a Japanese page run through Google's translator where the author had gone some distance in working out the hows and wherefores of the Wacom digitizer technology with respect how the X,Y coordinates are determined. It looks like you can do some tweaking if you're persistent in working out how everything fits together.

    Here's the raw Japanese version of the page. . .

    http://stcat.jpn.org/how04_01.html

    The author was looking at the Cintiq machines, but the settings probably apply to Tablets as well to some extent.

    Looks like it could be a neat project but it doesn't directly interest me, so I'll leave it to others to investigate.

    Cheers and have fun!
     
  6. thatcomicsguy

    thatcomicsguy Scribbler - Standard Member Senior Member

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    Just a quick note on tweaking pressure sensitivity. . .

    There is a sweet little third party freebie tool which allows a user in a nice GUI to adjust the pressure curve on a pen very easily. This was posted some time ago elsewhere on the forum, and I'd not looked at it since.

    Well, the guys who are responsible for that piece of software haven't been idle. The latest version is quite powerful and usable where the first was a bit baffling, I found. Check it out here. . .

    Tablet Pressure Curve Tool Secret Laboratory

    The one thing I'd note which I still found confusing is that there are two settings for each pen sensor, two for the tip and two for the eraser. (The difference depends on whether or not you are holding down the pen button while drawing or 'erasing'). The GUI tool doesn't make it clear which is which when you're setting the curves, or that you need to even think about it. But once I figured out what was going on, it became simple. Other than that design confusion, it's a decent little tool which I'll now be using instead of all that manual driver code tweaking.
     
  7. smslocum

    smslocum Earnest Pilgrim

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    This is a wonderful thread. Figuring out ways to perfect the calibration of this guy is a fond dream of mine. Nice to have an exotic (Japanese) lead.

    As the great Dan Reeder says, (we've) got all the F-ing work we need.
     
    Last edited by a moderator: May 18, 2015
  8. Steve B

    Steve B Moderator Moderator

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    Gotta agree. I did this yesterday and love it. I set my base input at 10 and moved the center dot down lower, and lowered my max to something like 225. I now have a very delicate touch kind of pen that lets me have very very light lines with very little pressure and yet I can get full opacity with less actual physical pressure as well.

    A very simple and useful tool.
     
  9. Steve B

    Steve B Moderator Moderator

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    It does have a pull-down toggle in the upper right though, to choose eraser or pencil. Is that what you're thinking of?
     
  10. Aicent

    Aicent Pen Pal - Newbie

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    Wow This is just amazing, thank you so so much thatscomics guy !
     
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