12 Replies Latest reply on Feb 17, 2015 9:46 AM by trshaner

    How to reduce purple color cast in high ISO Nikon D4 and D810 photos

    dorffersmatt Level 1

      In low-light photos taken with my D4 and D810 I often (but not always) get a severe purple color cast in the dark areas of the photo. I'm going to try posting a link to an example of one such photo, which I've put in my Dropbox account. I hope this works:

       

      Dropbox - Example of magenta color cast-001.jpg

       

      If the link works, you'll see what I mean: the dark areas are purple, not black as they should be. This was taken at the dress rehearsal for a play at ISO 3200, about the lowest ISO that I could get away with. The purple cast seems more pronounced along the edges of the photo.

       

      I've read a bit about "amp glow"; is that what I'm seeing here? If it is, what can I do about it? Turning the camera off and on again and again to try to cool the sensor and the nearby electronics isn't much of an option.

       

      And whether it's "amp glow" or something else, is there a good way to deal with it in Lightroom? I've had some success with reducing the purple saturation (and sometimes the purple luminance as well) in the "HSL" panel, but that becomes a problem if there are important elements in the photo which are SUPPOSED to be purple.

       

      Any and all advice would be welcome.

        • 1. Re: How to reduce purple color cast in high ISO Nikon D4 and D810 photos
          JimHess Adobe Community Professional & MVP

          I was able to get rid of a lot of it using the color noise adjustment and luminance adjustment in the Camera Raw filter. You could do the same in the Camera Raw plug-in or in the detail panel in Lightroom. It didn't get rid of all of it but it did remove a lot.

          Example of magenta color cast-001.jpg

          • 2. Re: How to reduce purple color cast in high ISO Nikon D4 and D810 photos
            dorffersmatt Level 1

            Jim, thanks for the suggestions. You mentioned being able to get the same results in Lightroom's "Detail" panel as you got in the Camera Raw filter. I tried using the "Color" slider in the "Detail" panel, but even pushing it to 100 didn't make a visible difference for me (though lowering it to 0 from the default value of 25 made a huge difference—and it was terrible). As for the "Luminance" slider, I don't want to use that more than I have to because it makes everything in the photo look too smooth—almost plastic-like.

             

            Is the Camera Raw filter something that you use inside of Photoshop? If it is, maybe I can't use it because I only have CS5, not CS6 or CC.

            • 3. Re: How to reduce purple color cast in high ISO Nikon D4 and D810 photos
              JimHess Adobe Community Professional & MVP

              That Camera Raw filter is only available in Photoshop CC. I must have been dreaming last night, because the color noise slider didn't work for me this morning either. The luminance slider seems to remove some of it. Then I used the gradual filter and the radial filter in the Camera Raw filter To reduce the shadows and the exposure in some of those dark areas. It helps some, but I still am not able to get rid of all of it. I also used the brush tool in the Camera Raw filter to reduce the shadows level and dropped exposure a little and brushed around a few areas. If I had taken more time I could have removed some more. It would take a lot of individual image work to remove that noise .But all of these tools that I'm using I don't think are available in Camera Raw for the version of Photoshop you are using.

               

              Example of magenta color cast-001.jpg

              • 4. Re: How to reduce purple color cast in high ISO Nikon D4 and D810 photos
                Rafael Aviles Level 3

                Another approach is to use the HSL panel (in Camera Raw or in Lightroom) and desaturate the Purple and Magenta colors, and also reduce their luminance. I also reduced the luminance of the Blues a little. Then, on the Details panel, a little noise reduction in both Luminance and Color.

                Example of magenta color cast-001_2.jpg

                • 5. Re: How to reduce purple color cast in high ISO Nikon D4 and D810 photos
                  JimHess Adobe Community Professional & MVP

                  There are obviously different ways to work with the image. The OP indicated that they didn't want to use the color tools. The radial filter and the brush with reduced exposure and shadows seems to do a pretty job in Lightroom 5. But it can be a little tedious if you have a lot of images to work with. If the original image was shot in raw, I would like to see what could have been done with it.

                  • 6. Re: How to reduce purple color cast in high ISO Nikon D4 and D810 photos
                    Rafael Aviles Level 3

                    Right, I missed that. And, it only works here because there is no purple or magenta elsewhere in the image.

                    • 7. Re: How to reduce purple color cast in high ISO Nikon D4 and D810 photos
                      JimHess Adobe Community Professional & MVP

                      I wasn't criticizing your method. I just tried to do it without using the color adjustments. There's a lot of noise in that image, making it difficult to work with.

                      • 9. Re: How to reduce purple color cast in high ISO Nikon D4 and D810 photos
                        trshaner Adobe Community Professional & MVP

                        JimHess wrote:

                         

                        There are obviously different ways to work with the image. The OP indicated that they didn't want to use the color tools.

                        The Split Toning panel can be used very effectively to remove the purple color cast in the background shadow area. You may also want to lower the Lens Profile> Vignetting setting to reduce the edge "glow." You can also use the Manual> Lens Vignetting control to reduce it further (see below).

                         

                        NOTE: The HSL controls affect ALL tones including those that may not need adjusting. The Split Toning controls target highlight and shadow areas using  separate controls with the cross-over threshold adjusted using the Balance control.

                        You can 'Sync' these Develop settings across multiple images that are similar and even create a Develop preset with these two control settings for future use. I also suggest using some Luminance & Color NR ( Amount 10-15). High ISO noisy images that are resized (Export, Printing, etc.) may appear lighter due to the interpolation algorithm sampling noise during scaling. A small amount of NR prevents this from occurring and shouldn't affect image sharpness significantly.

                         

                        Example of magenta color cast-001-NR and Split Toning_Compare.jpg

                        • 10. Re: How to reduce purple color cast in high ISO Nikon D4 and D810 photos
                          dorffersmatt Level 1

                          Hearty thanks to all three of you for your suggestions. Trshaner's ideas are especially eye-opening because I've never touched the "Split-toning" panel in my life.

                           

                          Interestingly, my e-mail says there was another post about how to reduce the purple cast with proper in-camera settings, but now that post seems to have been deleted (by the poster? by somebody at Adobe?), which is a shame because I would have liked to get some more information from that poster. Drugstore, if you're still reading this thread, a couple of questions for you:

                           

                          1) You said that you sometimes see the purple cast with your D4 and D810 if the white balance isn't set properly. What would you consider a proper white balance setting for a situation such as this one? It was the dress rehearsal for a play, with constantly shifting lighting. I just left the white balance on "Auto"; how would you have approached the situation?

                           

                          2) You said that you also sometimes see it if "you activate the lens correction in LR while in raw mode and exposure is too low." Could you elaborate on that? Do you mean that I shouldn't use "Enable profile corrections" in the "Lens Corrections" panel?

                          • 11. Re: How to reduce purple color cast in high ISO Nikon D4 and D810 photos
                            trshaner Adobe Community Professional & MVP

                            dorffersmatt wrote:

                            Interestingly, my e-mail says there was another post about how to reduce the purple cast with proper in-camera settings, but now that post seems to have been deleted (by the poster? by somebody at Adobe?)

                            The poster (Drugstore) may have deleted the post after reading further because it may not have been relevant......just a guess. If you're shooting raw format the in-camera settings such as white balance are not applied to the image file, but they are for JPEGs. The suggestions I provided are applicable to both JPEG and raw image files, but you'll get the best results using raw format.

                             

                            dorffersmatt wrote:


                            1) You said that you sometimes see the purple cast with your D4 and D810 if the white balance isn't set properly. What would you consider a proper white balance setting for a situation such as this one? It was the dress rehearsal for a play, with constantly shifting lighting. I just left the white balance on "Auto"; how would you have approached the situation?

                            Again, this only applies to JPEG format image files. For raw image files the WB EXIF data is read and set accordingly inside LR. For JPEGs the image data has the (incorrect?) WB applied in-camera, which compromises the dynamic range of the JPEG 8-bit/color data. Raw files are 16 bit/color.

                             

                            dorffersmatt wrote:

                            2) You said that you also sometimes see it if "you activate the lens correction in LR while in raw mode and exposure is too low." Could you elaborate on that? Do you mean that I shouldn't use "Enable profile corrections" in the "Lens Corrections" panel?

                            I'm guessing this refers to what you call "amp glow" (amplifier glow). It usually appears as a higher exposure level around the edge of the image and may be confined to one area (top, bottom, sides). By turning off Lens Profile corrections ( "Enable profile corrections") Vignetting correction is not applied, which reduces the exposure level in the corners and frame edges. Some cameras automatically apply distortion and/or vignetting correction in-camera when shooting in JPEG format. Again, this is just another reason why you want to use raw format to get the best results inside LR.

                            • 12. Re: How to reduce purple color cast in high ISO Nikon D4 and D810 photos
                              trshaner Adobe Community Professional & MVP

                              dorffersmatt wrote:

                               

                              Hearty thanks to all three of you for your suggestions. Trshaner's ideas are especially eye-opening because I've never touched the "Split-toning" panel in my life.

                              You can fine-tune the Split Toning adjustments further to remove any discoloration of the midtones and highlights caused by the Shadows settings. In the Split Toning panel add or subtract 180 from the Shadows 'Hue' setting used (80) and enter it into the Highlights 'Hue' setting (80 + 180 = 260). This is the "subtractive" hue." Next adjust the Split Toning panel's Highlights 'Saturation' slider to remove any color cast from the midtones and highlights introduced by the Shadows settings. You may need to readjust the Balance slider and/or Shadows Saturation, but it wasn't necessary with these settings. Here are the Split Toning settings that work well with the posted JPEG: