12 Replies Latest reply on May 12, 2009 9:53 AM by sfjedi

    Improved Brush Stroke Engine

    sfjedi Level 1

      Some people might call this a bug, but I wouldn't classify it as such because everything works as intended.

       

      One weakness I've struggled with in both Adobe Photoshop AND Corel PHOTO-PAINT is the paint brush engine. That is, I would find the strokes to create this "skip rock" effect, for lack of a better explanation. As it works today, PS creates brush strokes with dab spacing. I might not know the correct terminology or exactly how it's working, but I can see with my own eyes how it's programmed. You get one dab here and you have to move your mouse or tablet pen a certain amount to get another dab.

       

      I believe the Corel Painter engine for brush strokes would be beneficial to Photoshop as well. As a programmer, I also understand the limitation to such a stroke engine. That is, you would really need to complete a stroke before knowing exactly what it should look like. I think the way Painter handles it is the best solution I can think of. PS could just show brush strokes as they are currently until the user lets go of the mouse button or relieves pressure from the tablet pen. Then, the calculations could be made to produce a smoothe brush stroke, which looks pretty much exactly the same as what they saw in preview; only, without any side effects, splotchiness or "skip rock" crap.

       

      Granted, if you can make it all work live that would be awesome! But I'm guessing the performance hit might be too extreme.

       

      To illustrate what I'm talking about with this "skip rock" effect, pay very close attention to the image below, which is a screenshot of the Photoshop viewport. It's extremely subtle so you might have to look close or squint your eyes a little bit, but the brush stroke is flawed! No real-life brush stroke would EVER look like that!

       

      skiprock.jpg

      Actually, I can see it better when I look at it from a bit of a distance (2 feet) rather than close up.

        • 1. Re: Improved Brush Stroke Engine
          sfjedi Level 1

          In another discussion, Reynolds (Mark) wrote:

           

          Photoshops brush tools at the moment are not set  up to simulate naturalistic effects at all. This has advantages and disadvantages - the advantage is that you can customise brushes in very complex ways that in some ways go far beyond what you can do in natural media.

           

          I understand these advantages of the current brush tools and by all means don't wish for them to change, but the brush system should be smart enough to know when we are trying to achieve these effects vs. when we are trying to do an actual paintbrush stroke.

          • 2. Re: Improved Brush Stroke Engine
            Reynolds (Mark) Level 4

            sigh… You need to look into the brush controls more deeply. Two controls in particular "Spacing" and the "Airbrush" checkbox.

            • 3. Re: Improved Brush Stroke Engine
              sfjedi Level 1

              Reynolds (Mark) wrote:

               

              sigh… You need to look into the brush controls more deeply. Two controls in particular "Spacing" and the "Airbrush" checkbox.

               

              Dude I know what brush (dab) spacing is and the airbrush checkbox too. I've used them both, but this is a fundamental problem with the way brushes are rendered, regardless of spacing! Dab spacing is a flawed concept when looking for a natural brush response.

              • 4. Re: Improved Brush Stroke Engine
                harry teasley Level 1

                Spacing and smoothing fix this. No, really.

                • 5. Re: Improved Brush Stroke Engine
                  sfjedi Level 1

                  harry teasley wrote:

                   

                  Spacing and smoothing fix this. No, really.

                   

                  Hmm... really? Then what's this? If your eyes aren't good enough you might have to save it and zoom in, but here it is...

                   

                  spacing.jpg

                   

                  Learn the tool?

                  • 6. Re: Improved Brush Stroke Engine
                    harry teasley Level 1

                    I don't see that behavior, with the brushes I've tried.

                    • 7. Re: Improved Brush Stroke Engine
                      sfjedi Level 1

                      harry teasley wrote:

                       

                      I don't see that behavior, with the brushes I've tried.

                       

                      It is less apparent with certain brushes, but the problem will persist until the brush engine is fixed to make a more natural effect. I'm not saying to rid of the current brush engine, as it's extremely beneficial for certain scatter effects and such, but definitely change how it works when these scatter effects are NOT being used!

                      • 8. Re: Improved Brush Stroke Engine
                        Reynolds (Mark) Level 4

                        Do you use a Wacom? Are you using Windows OS? I also have never seen these problems. There are hunderds of people, matte painters, illustrators who all use photoshops brush engine, without complaints. It may be some idiotic thing like trying to paint with a mouse, someting to do with uneveness is sampling, probably related to windows clunky input engine, thats my theory

                        • 9. Re: Improved Brush Stroke Engine
                          harry teasley Level 1

                          I would guess that it may be possible to define a custom brush shape (I'm envisioning a main blob, with a stray pixel far away from it, as being the brush source) where it may push the spacing/smoothing function to an extreme, such that maybe you would get artifacts with it. It might be possible.

                           

                          ....

                           

                          Nope, that attempt didn't produce the effect. I can't get this behavior.

                          • 10. Re: Improved Brush Stroke Engine
                            sfjedi Level 1

                            I'm using Vista Home Premium (64-bit) w/ PS v11.0. Yes, I use a tablet, but for the purposes of this demonstration I created 2 paths and stroked them with a brush to maintain consistency between them.

                             

                            Yeah, I can't reproduce this at school for some reason, but I can't find the same brush here either.

                            • 11. Re: Improved Brush Stroke Engine
                              Reynolds (Mark) Level 4

                              A sampled brush, thats one that has been created - can have all kinds of problems, maybe the edge isnt hard enough? there are grey pixels in the brush causing unwanted transparency. The standard Photoshop round, controlled feathering brushes are different and are resolution independent.Think of these like vector brushes- they rasterise at the size of the diameter.

                              • 12. Re: Improved Brush Stroke Engine
                                sfjedi Level 1

                                You know, it's odd. This particular brush that I used is built-in to Photoshop; yet, I can't find it on the other CS4 installations at school.

                                 

                                I realize what you're saying about the standard round brushes being treated like vector and all, but even if this were the case, this same side effect could occur. Programmatically, the way the brush is being drawn is not meant for naturalistic effects.

                                 

                                Theoretically, with this supposed new solution, spacing could be set to zero and that's when PS would know to switch the brush stroke engine from traditional to natural.

                                 

                                It would have to draw it differently though.