Announcement

Collapse
No announcement yet.

color noise

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • color noise

    Hello all!
    I did a quick search in the forums for techniques used to eliminate color noise in shadows.
    I am aware of the reduce noise filter but it seems to give that gaussian blur effect.
    Another have any other methods?

  • #2
    Re: color noise

    Check the channels often noise can be more pronounced in one of the channels and then you can look at reducing the noise there. you can also try to color correct the color in the shadows to make it blend better with the shadow.

    Comment


    • #3
      Re: color noise

      Jennifer, that type of noise is quite common in underexposed areas of digital images. I have found the mosteffective way to reduce or eliminate the noise without over blurring the image is a good noise reduction plugin like Noiseware, Neat Image , or Noise Ninja. I find Noiseware the best of the 3.
      Regards, Murray

      Comment


      • #4
        Re: color noise

        Easiest way (in Photoshop):

        1) Duplicate layer
        2) Change blend mode to "Color"
        3) Gaussian blur (1-2 pixels is usually enough)
        4) Merge

        Use a luminosity mask or Select -> Color Range to perform step (1) on just the shadow areas if you like.

        Comment


        • #5
          Re: color noise

          im not necessarily looking for the easiest way
          but i will definately give this a whirl..
          thanks a bunch

          Comment


          • #6
            Re: color noise

            Originally posted by creeduk View Post
            Check the channels often noise can be more pronounced in one of the channels and then you can look at reducing the noise there. you can also try to color correct the color in the shadows to make it blend better with the shadow.
            how do i reduce the noise in individual channels?
            dup channel then blur or reduce noise filter?

            and thanks for your help

            Comment


            • #7
              Re: color noise

              Convert to Lab.

              Blur the a and b channels.

              Convert back to RGB and place on top of your original.

              If your shadow areas are pronounced, you can probably blend using Blend-if sliders to smooth the transition into the shadow range. Otherwise, mask and paint back to taste.

              Comment


              • #8
                Re: color noise

                edgework gave one the most used methods, using LAB.

                TO do it in RGB you can simply move to the channels tab, select the desired channel, and the Noise reduction filter is still available and will function on that channel alone.

                Or under the Noise Reduction panel, select advanced and you will now see a new tab "Per Channel" this area allows you to address the channels separately.

                Comment


                • #9
                  Re: color noise

                  Edgework certain gave the best example but I would add a very important step. You will want to blur the A and B with surface blur or use dust and scratches to preserve the color detail of objects that have sharp edges. To visualize the technique, since a and b are usually hard to see, you can add a crazy adjustment curve layer set to color blending mode over the BG layer to increase the contrast of the two channels while you play with the blur filters. Another way, often overlooked in photoshop, is to first select the two channels using shift-click. THEN, press the ~ key which will show you the whole image while you are only working on the two color channels you have selected. I was just working on a painting that had subtle details of color and it was the first image I couldn't successfully work on in Neat Image (IMHO, the very best of all the noise programs) LAB is certainly the ONLY way you should approach this since color blending in RGB is VERY bad. This is a very difficult thing to explain, but better shown by a test.
                  Attached Files

                  Comment


                  • #10
                    Re: color noise

                    After posting the previous test, I concluded that this was an unfair and inaccurate presentation of the difference. The previous test was taken right from Photoshop Lab Color: The Canyon Conundrum: And Other Adventures in The Most Powerful Colorspace
                    By DAN MARGULIS
                    I think Dan's examples are unfair since the top right image (Lab version) didn't show the L channel which made it look so much better than the RGB (set to color mode) that was the bottom right image. I have made my own examples that show both Lab and RGB without any luminance detail change. Notice how RGB brightens some of the colors and darkens others. The lab, on the other hand, is able to blur them without brightening or darkening any of them.
                    Attached Files
                    Last edited by seedomo; 10-24-2007, 02:33 PM.

                    Comment


                    • #11
                      Re: color noise

                      Originally posted by seedomo View Post
                      After make the previous test, I concluded that this was an unfair an inaccurate presentation of the difference. The previous test was taken right from Photoshop Lab Color: The Canyon Conundrum: And Other Adventures in The Most Powerful Colorspace
                      By DAN MARGULIS
                      I think Dan's examples are unfair since the top right image (Lab version) didn't show the L channel which made it look so much better than the RGB (set to color mode) that was the bottom right image. I have made my own examples that show both Lab and RGB without any luminance detail change. Notice how RGB brightens some of the colors and darkens others. The lab, on the other hand, is able to blur them without brightening or darkening any of them.
                      Your point's valid; however, she specifically mentioned color noise in shadows which have little color to speak of. My suggestion addressed narrowly targeting the shadow areas, avoiding the pitfalls you bring up.

                      Comment


                      • #12
                        Re: color noise

                        Fair enough. I guess I was really just wanting to share a little bit about what I have learned recently about the techniques of removing noise. That book was a real eye opener. Although I have to say its a good thing Dan isn't a photographer cause his ability to see beauty or retouch or sharpen is very off. Its kind of strange cause while his techniques are very useful, he seems to use them to further a point not create the best looking image. Most of his finals are very disturbing indeed!

                        Comment


                        • #13
                          Re: color noise

                          Originally posted by Damo77 View Post
                          1) Duplicate layer
                          2) Change blend mode to "Color"
                          3) Gaussian blur (1-2 pixels is usually enough)
                          4) Merge
                          Originally posted by edgework View Post
                          Convert to Lab.

                          Blur the a and b channels.

                          Convert back to RGB and place on top of your original.
                          Our methods are exactly the same, but mine doesn't require a colour space conversion. Space conversions should be avoided if possible.

                          The "Color" layer blending mode simulates the "a" and "b" channels in Lab mode.

                          Comment


                          • #14
                            Re: color noise

                            Originally posted by seedomo View Post
                            Edgework certain gave the best example but I would add a very important step. You will want to blur the A and B with surface blur or use dust and scratches to preserve the color detail of objects that have sharp edges. To visualize the technique, since a and b are usually hard to see, you can add a crazy adjustment curve layer set to color blending mode over the BG layer to increase the contrast of the two channels while you play with the blur filters. Another way, often overlooked in photoshop, is to first select the two channels using shift-click. THEN, press the ~ key which will show you the whole image while you are only working on the two color channels you have selected. I was just working on a painting that had subtle details of color and it was the first image I couldn't successfully work on in Neat Image (IMHO, the very best of all the noise programs) LAB is certainly the ONLY way you should approach this since color blending in RGB is VERY bad. This is a very difficult thing to explain, but better shown by a test.

                            great test! thanks so much. a visual definately helps when trying to figure out the best methods.

                            I see that the top right is gaussian of A B.
                            Is bottom right the surface blur?

                            Comment

                            Related Topics

                            Collapse

                            • Ken Fournelle
                              Noise Reduction in the Work Flow
                              by Ken Fournelle
                              Where do people like to use a noise reduction plug-in during he work flow? On the duplicate background layer at the beginning? After global corrections to color, contrast and levels? The end of the process?

                              Ken
                              09-05-2004, 04:02 PM
                            • blackphnx
                              Getting rid of noise
                              by blackphnx
                              Hi guys! I'm new here. I feel very lucky that i finally found this kind of forum.

                              My concern is that how can I remove noise from the image or reduce it. Some shots are take at high ISO and the noise is active or its obvious. I tried noise ninja but there are too many settings which confuse...
                              07-17-2006, 11:01 PM
                            • nebgranny
                              Noise: Can anymore be done?
                              by nebgranny
                              Can not post full pic, but hope this is big enough. Still working on those really dark pictures. This one was taken at night at a football game. I have done a levels adjustment and then I ran it through neat image twice. I still have a good bit of the pixles as noted in posted image.

                              ...
                              10-22-2005, 07:12 PM
                            • scott watson
                              Noise Reduction
                              by scott watson
                              After trying out Noiseware, Neat Image and Noise Ninja plugins I decided to purchase Noiseware Pro.
                              I would like to know when is the best time to get rid of the noise. On the images I work on I will be doing alot of cloning to remove various elements in the image.
                              Do you think its...
                              12-03-2006, 12:21 PM
                            • imann08
                              Getting rid of digital noise in LAB
                              by imann08
                              In a recent trip to London, I took a ton of pictures. Almost all of them were taken with an ISO that was much too high. The result was enough digital noise to make one go deaf. Getting rid of digital noise has been one of the areas that I have had the most trouble with. I don't know if I am dealing...
                              02-18-2006, 09:58 PM
                            Working...
                            X