12 Replies Latest reply on Oct 5, 2017 4:49 AM by melissapiccone

    Photo discolorisation

    patb75380271

      Hello everybody,

      My photoshop picture seems to be having some green parts on my picture which is weird. As far as I know this isn't guide lines, I've used photoshop for 6 years and I have never really encountered this problem.

       

      When I copy and paste that certain area into paint, there isn't any green parts but on photoshop I can see it.. so my monitor isn't the problem.

       

      Picture: Imgur: The most awesome images on the Internet

       

      Look closely, you will see the green parts in the picture when I use a gradient overlay. It's weird man.

        • 1. Re: Photo discolorisation
          melissapiccone Adobe Community Professional

          I can't see the image, can you upload it directly here?

          • 2. Re: Photo discolorisation
            ahmed_waheib Level 2

            Can you please upload your screenshot here with your software version & your operating system.

            • 3. Re: Photo discolorisation
              davescm Adobe Community Professional

              Your dark grey image at your link shows some banding in the dark areas which is common when using a gradient. it is caused by the gradual steps in RGB levels used for your gradient (there are not many down at the dark end) where the Red, Green and Blue channels do not step down exactly together.

               

              You can avoid it by :

              a. Working in 16 bit mode rather than 8 bit giving more steps therefore a smoother ramp. Although may still see some banding on your display which is likely to be working with only 8 bits - it will not be in your image

              b.  Adding a little noise to the image /gradient . It does not take much to make the banding invisible.

               

              Dave

              • 4. Re: Photo discolorisation
                patb75380271 Level 1

                Sl7nnex.png

                 

                To the people who couldn't see the picture ^

                 

                davescm

                 

                Yes, I do work in 8 bit. You recommend 16 bit by what I can see, should I use 16 bit from now on if I use smooth gradients or..?

                • 5. Re: Photo discolorisation
                  davescm Adobe Community Professional

                  Stick with 16 bit.

                  32 bit is for specialist use such as HDR or 3D modelled worlds etc. Some of the features of Photoshop (such as various blending modes and some adjustment layers) are not available in 32 bit

                   

                  To explain in simplistic terms :

                  8 bit  uses 256 levels for each colour from 0 off to 255 (fully on) .

                  16 bit (which for various reasons in Photoshop is actually 15 bit +1) uses 32769 levels to split that same range between the darkest and lightest of each colour.

                   

                   

                  32 bit floating point allows levels beyond black and beyond white of 8/16 bit. This happens in the real world. However, these cannot be displayed on our monitors or prints which is why tone mapping is used to decide how that extended range maps back to the range of 8/16 bit for display, just as you would adjust the controls on a camera to select which areas will fall into the range that can be captured by that camera.

                   

                  Like I said at the start though - just stick with 16 bit for your purpose.

                   

                  Dave

                  • 6. Re: Photo discolorisation
                    patb75380271 Level 1

                    Even with 16 bit, I can see the banding and it's just my OCD in general that makes me annoyed about it.

                    Should I just ignore it and stick with that gradient or switch it up?

                     

                    When I checked out other peoples arts they have gradients with colours of for example #121212 (from bottom) to #17191b (to top) so idk I have banding and they don't? It makes no sense...

                    • 7. Re: Photo discolorisation
                      davescm Adobe Community Professional

                      Create a gradient after switching to 16 bit and check with the eye dropper and info panel (switch it to 16 bit) that the banding is still in your image.

                      It should not be - remember your monitor display will be working in 8 bit (some expensive monitors and cards work in 10 bit) so you may still see some banding from your display chain which is not in your actual image. Noise can help with this but be careful - you will be  covering up a shortcoming of your display by adjusting your image.

                       

                      Dave

                      • 8. Re: Photo discolorisation
                        patb75380271 Level 1

                        I can still see a little bit of banding but it's not that much of a problem, thank you anyway!

                        • 9. Re: Photo discolorisation
                          D Fosse Adobe Community Professional & MVP

                          Yes, in a 16 bit file, any banding you see is in your display system.

                           

                          In a standard 8 bit display system you will always see the 256 individual steps from black to white (per channel). These 256 levels should ideally be evenly distributed. If they aren't, it can be because of the panel itself, or a defective monitor profile.

                           

                          However, the most common cause for irregular banding is color corrections in the video card such as calibration curves. This problem disappears in a 10-bit display pipeline, as it does with integrated hardware calibration in high-end monitors with internal high-bit LUT.

                          • 10. Re: Photo discolorisation
                            melissapiccone Adobe Community Professional

                            I still can't see the picture - what??? Screen Shot 2017-10-04 at 2.55.59 PM.png

                            • 11. Re: Photo discolorisation
                              D Fosse Adobe Community Professional & MVP

                              That is the picture. It's a very shallow gradient. This is it with a steep curve on top:

                              untitled2.png

                              • 12. Re: Photo discolorisation
                                melissapiccone Adobe Community Professional

                                I'm glad your eyes are better than mine   . i just assumed it wasn't showing up.