11 Replies Latest reply on Oct 23, 2016 11:09 AM by J Isner

    Lightroom Adjustment brush with Auto Mask leaves ugly artifacts on flat surfaces

    J Isner Level 1

      Ever since I started using Lightroom, I have left "Auto Mask" turned on when using the Adjustment brush.   I recently began to notice that the brush leaves artifacts that are visible even when viewing at less than 1:1.  At first I thought it was a defect in my (new) camera sensor (the artifacts look like bad pixels), but I traced it to the Adjustment Brush.   Has anyone else noticed this?

       

      The screenshots below from a raw file that has had no other adjustments made to it.  It's a portrait, so there is normal amount of splotchiness on the skin, which is not my concern!  It's those hard-edged artifacts that are left by the brush with Auto Mask On.  

       

      The brush is adding 0.60 Exposure Value.  Feather = 100%, Flow = 100%, density = 50.  Using Lightroom CC 2015.7.

       

       

      Lightroom Auto Mask Artifacts viewing at 100 percent.jpg

       

       

       

      lightroom auto mask artifacts viewing at 200 percent.jpg

        • 1. Re: Lightroom Adjustment brush with Auto Mask leaves ugly artifacts on flat surfaces
          wobertc Adobe Community Professional

          This is a well known and discussed characteristic of the brush in Auto Mask mode.

           

          To explain simply- When you click the brush to start brushing, LR reads the pixel that is exactly under the cross-hairs in the brush circular cursor, then as you brush it only changes pixels that are the same as the one it sampled- no others! So a different toned pixel is not changed even if it is under the brush circle. Hence you will see the artifacts you mention. Your images look even-toned but the pixels do change slightly in luminance, so the brush is still selective in Auto-mask mode.

           

          The answer- Do not ever use Auto-Mask when brushing areas that may look even-toned. Save Auto-mask for brushing along edges where the image pixels change markedly.

           

          One aspect of Auto-mask is that if you frequently click the mouse button as you brush then the brush 'learns' to sample more varied tones.

          • 2. Re: Lightroom Adjustment brush with Auto Mask leaves ugly artifacts on flat surfaces
            J Isner Level 1

            Thank you very much for your answer. 

             

            I only began noticing the problem recently when processing raw files from a new Sony A6000.  I do not have the problem with Nikon D610 or D7000 raw files.  I suspect that the problem is amplified by the (inferior?) quality of the Sony raw files, which must contain digital artifacts.  The brush is simply amplifying those artifacts.   Could it be a bad sensor?  Or is the brush amplifying noise from shooting at ISO 800?  Reducing noise before brushing doesn't seem to make a difference.

             

            My policy from now on will be: "Auto Mask Considered Harmful."

            • 3. Re: Lightroom Adjustment brush with Auto Mask leaves ugly artifacts on flat surfaces
              trshaner Adobe Community Professional & MVP

              J Isner wrote:

               

              My policy from now on will be: "Auto Mask Considered Harmful."

              There is an easy way to correct this issue in image areas that have a defined border (lighter darker, different color). Use a smaller Adjustment Brush with Auto Mask checked to paint in just the outside border of the area you want to correct. Once that is complete uncheck Auto Mask and paint in the remaining central area with a larger brush. Next check 'Show Selected Mask Overlay,' hold down the ALT key, and 'Erase' any spill-over outside the area to be corrected. With some practice it doesn't take much longer. Using a Wacom tablet and pen helps to speed the process.

               

              You may also want to use a lower Feather setting with Auto Mask selected to help constrain the mask. If you're painting a correction in area that has no defined border I suggest not using Auto Mask at all. If you're still having a problem show us the full image and the area you are trying to correct.

              • 4. Re: Lightroom Adjustment brush with Auto Mask leaves ugly artifacts on flat surfaces
                J Isner Level 1

                Generally, one uses Auto Mask to paint an area with a well-defined border, the objective being that the adjustment should not cross the border.  The interior area may be quite large.  So your emphasis on the border itself mystifies me. My problem is not at the border, it's in the interior, where the brush leaves artifacts in its wake.

                 

                I simply do not believe that the problem is in the way I am using (and always have used) the adjustment brush.  Just now, I experimented with the brush on several raw files, some from Nikon D610 and some from Sony A6000.  With Auto Mask ON, painting my Nikon raw files works just fine: It detects the border and does not paint outside.  With the Sony raw files, the brush also observes the border, but it leaves artifacts behind in the interior.  I believe it is amplifying defects in the Sony raw files.  In the future, I will not use Auto Mask with my Sony raw files.

                 

                I should have mentioned that my Sony images are almost all shot at ISO 1600 and my Nikon images are almost all shot at ISO 100. With a Sony raw shot at ISO 100, Auto Mask is well-behaved.  Again, I believe, that the brush with Auto Mask ON is amplifying noise. 

                 

                So I revise my policy: "Auto Mask with high ISO Sony A6000 raw files considered harmful."

                • 5. Re: Lightroom Adjustment brush with Auto Mask leaves ugly artifacts on flat surfaces
                  J Isner Level 1

                  To put it succinctly, I think Auto Mask is treating interior noise as "outside" pixels and not applying the correction to them.

                  • 6. Re: Lightroom Adjustment brush with Auto Mask leaves ugly artifacts on flat surfaces
                    trshaner Adobe Community Professional & MVP

                    J Isner wrote:

                     

                    I should have mentioned that my Sony images are almost all shot at ISO 1600 and my Nikon images are almost all shot at ISO 100. With a Sony raw shot at ISO 100, Auto Mask is well-behaved.

                    The suggestion mentioned by I outlined) works well when the image image area has differences in density or color not due to noise.

                     

                    For your high ISO images try using a smaller brush size to first outline the image and then use a larger brush size to fill-in the remaining area, both with Auto Mask unselected.

                     

                    J Isner wrote:

                     

                    Again, I believe, that the brush with Auto Mask ON is amplifying noise.

                    Although it has the appearance of amplifying noise the correction mask is simply not being applied to the noise spots (i.e. holes in the mask).

                    • 7. Re: Lightroom Adjustment brush with Auto Mask leaves ugly artifacts on flat surfaces
                      J Isner Level 1

                      +trshaner.  I marked your answer as correct because it makes sense:  The brush does not apply the mask to noise.  This is not "amplification" per se, but it exaggerates the noise more or less, depending on what adjustment is being brushed.

                       

                      This has got to be a bug!  The brush's sophisticated edge-detection algorithm obviously does not handle noise.  Random noise should be easy to distinguish from an edge.

                      • 8. Re: Lightroom Adjustment brush with Auto Mask leaves ugly artifacts on flat surfaces
                        trshaner Adobe Community Professional & MVP

                        J Isner wrote:

                         

                        This has got to be a bug! The brush's sophisticated edge-detection algorithm obviously does not handle noise. Random noise should be easy to distinguish from an edge.

                        I think the problem is that the Local Adjustment Brush controls are applied to the image before the Global controls, such as Detail panel Noise Reduction. I applied Luminance 35 NR to a ISO 3200 raw  image with visible noise and then used Edit in PS to create a TIFF file. Applying the Adjustment Brush with +1.0 Exposure using Auto Mask enabled works much better using the PS TIFF with NR applied (see below).

                         

                        You can offer this suggestion as an 'Idea' here: Photoshop Family Customer Community Someone has mentioned the problem, but no traction: Lightroom 4: Auto Mask and high ISO (noisy) photos | Photoshop Family Customer Community

                        Adjustment Brush Auto Mask - High ISO Images.jpg

                        • 9. Re: Lightroom Adjustment brush with Auto Mask leaves ugly artifacts on flat surfaces
                          J Isner Level 1

                          Let me see if I understand: LR applies adjustments in a pre-determined order that is independent of the order in which the user applies them.   The order of the Develop module sub-panels is just a suggested workflow and does not control the actual order.  If LR always applies local adjustments before global ones, then if I reduce noise (global) and then paint +1.0 Exposure (local), LR paints exposure first and then reduces noise.  But painting exposure amplifies noise, making it harder to reduce, leaving ugly artifacts.

                           

                          In your example, you effectively reversed the order by doing the noise reduction in LR, sending to PS and saving a TIFF, bringing the TIFF back into LR and brushing in exposure.  The side-by-side comparison in the screenshot is convincing.

                           

                          I'm glad that someone else noticed this (the 4-year old discussion), but it's sad no one picked up on it.  I will post the 'idea' as you suggest.

                          • 10. Re: Lightroom Adjustment brush with Auto Mask leaves ugly artifacts on flat surfaces
                            trshaner Adobe Community Professional & MVP

                            I discovered this Local>Global order of adjustment application about 4 years ago: Re: In which order is the raw file rendered? At that post I also mentioned that Luiminance NR and Defringe control increase the real-time preview rendering time in the Develop module. This may be one of the reasons why Locals are applied before Globals–To prevent lag when using the Local controls. Unfortunately there have been numerous reports of control lag after applying multiple Adjustment Brush or Healing Brush spots with LR 6. Simply moving NR ahead of the Local controls will make this even worse.

                             

                            After thinking about this.......Adobe may be able to correct the Auto Mask issue by using a pre-rendered image bit map that has only Noise Reduction applied to it. This would be very similar to a Library 1:1 Preview like my TIFF file in reply #8. When Auto Mask is checked the bit map could be created real-time (i.e. a few seconds lag) with only Noise Reduction and perhaps Sharpening applied to it. The Develop module preview would still be the same as now, but in the background the Adjustment Brush mask is created using a separate bit map with Noise Reduction applied. As the mask is being created using the Adjustment Brush it can also be applied real-time to the Develop module preview. It is something that could be off-loaded to the GPU, which is currently not implemented in LR 6/CC 2015.

                             

                            This is a simplification as to what's required and doesn't address user interface issues. For example would a delay (up to 5 sec.) in being able to use the Adjustment Brush after checking 'Auto Mask' be tolerable? It would be OK to me if the Auto Mask feature worked better and saved time in applying the desired corrections. This may also allow Adobe to add a control for adjusting and refining the mask edge radius to eliminate halos and other artifacts that are sometimes visible.

                             

                            J Isner wrote:

                             

                            I'm glad that someone else noticed this (the 4-year old discussion), but it's sad no one picked up on it. I will post the 'idea' as you suggest.

                            Please put a link in a reply here to your post in the Photoshop Family forum and a link there to this post. Thank you!

                            • 11. Re: Lightroom Adjustment brush with Auto Mask leaves ugly artifacts on flat surfaces
                              J Isner Level 1

                              Great explanation!

                               

                              Here's a link to the post in Photoshop Family Forum:

                               

                              Adjustment brush with Auto Mask ON leaves ugly artifacts in noisy images | Photoshop Family Customer Community

                               

                              The post links back to this discussion.

                               

                               

                               

                              You write: would a delay (up to 5 sec.) in being able to use the Adjustment Brush after checking 'Auto Mask' be tolerable? 

                               

                              Definitely!