6 Replies Latest reply on Jan 29, 2016 11:29 PM by G.Hoffmann

    why does camera raw apply tint adjustment?

    dfielding720

      I opened a RAW image from my Canon 5D MkIII using a Canon 24-105mm lens in Adobe Camera RAW and it applies a tint adjustment (+6) even though the preferences are NOT set to apply any settings. Tint is the only adjustment it makes. Where is it coming from? I do not use the standard Canon 5D picture profiles. Sharpness, Contrast, Saturation are all zero'd out for a flat image.

       

      I noticed when I was working in Adobe Premiere, the clips had a greenish tint to them. I thought it might be the lighting, but I tested two different video lights, one was a set of 5000k Eiko CF's and the other was a Dracast bi-color LED, set to 5,000k. RAW images from both lights opened in Camera RAW have the same +6 tint setting.

        • 1. Re: why does camera raw apply tint adjustment?
          Trevor.Dennis Adobe Community Professional (Moderator)

          When you say Tint, do you mean that the image white balance appears to be wrong?  Or that a particular setting is defaulting to a non standard setting?

          • 2. Re: why does camera raw apply tint adjustment?
            dfielding720 Level 1

            In the Camera RAW window, there is Temperature and there is Tint. Every setting is ZERO except Tint. The White balance is 'As Shot'.

            • 3. Re: why does camera raw apply tint adjustment?
              G.Hoffmann Level 3

              White Balance As shot:

              ACR uses the camera white point settings. This defines a working point on the color temperature curve,

              which goes roughly from orange to blue. There may be a green or magenta tint left, transverse to the

              temperature curve. This is automatically compensated by tint adjustment. (plus) means more magenta.

               

              White Balance Auto:

              Assumed neutral areas are made neutral by moving the working point not only along the color temperature 

              curve but also transverse to it. Indicated is the correlated color temperature, but no tint.

               

              Color temperature curve:

              http://docs-hoffmann.de/coltemp18102003.pdf

               

              Not sure whether this helps, because it doesn't explain why the adjustments are handled like this.

               

              Best regards --Gernot Hoffmann

              • 4. Re: why does camera raw apply tint adjustment?
                dfielding720 Level 1

                Thanks Gernot,

                 

                I didn't expect to get such an excellent, albeit technical response to my generalized question. Very helpful. It gives me a clue as to a resolution. I have to admit I don't completely understand the necessity of the calculated tint adjustment. Is the adjustment specified by the camera due to the hardware/firmware or the color profile of the lens?

                 

                So, ACR reads the camera white point settings (from the EXIF data embedded in the RAW image?) and applies the tint adjustment. On one hand, I appreciate that ACR reads the EXIF and makes the correction. However, it doesn't appear that Lightroom or Premiere apply an automatic correction, leaving me to make the correction in post. I can make the corrections manually in the color utility/app if I can interpolate the value of +6 to whatever color app/utility I'm using.

                 

                I'll have to research the Canon 5DmkIII white point subject and how it is determined. I'll postulate that it's related to the lens used (assuming the firmware recognizes the lens used). I may have to make a tint adjustment in my camera settings>picture profile to compensate or... apply a LUT to the clips in post.

                 

                David

                • 5. Re: why does camera raw apply tint adjustment?
                  dfielding720 Level 1

                  Gernot,

                   

                  Now that I've had a chance to wrap my head around the color science, I understand it a little better. The 'imperfection' is not in the science, but the interpretation. Assuming the camera makes the proper calculation for 'tint' based on the kelvin value, as a photographer/videographer it's up to the software to read and interpret correctly. That's where the challenge comes in. Adobe Premiere isn't reading/applying the appropriate color correction from the EXIF data in the file. An educated guess.  The video editor attempted to adjust the tint away from green, but the model then gets rather magenta looking. His skin tones lean toward magenta as it is... always a challenge those 'red people'.

                   

                  What to do...

                  So, I gotta figure out whether the Canon 5DmkII and III's don't include the EXIF color correction in an H.264 video file or whether Premiere just doesn't read/interpret it.

                  • 6. Re: why does camera raw apply tint adjustment?
                    G.Hoffmann Level 3

                    David, thanks for the feedback.

                     

                    I'm familiar to some extent with color science, but I don't know, how the camera and Photoshop

                    adjust the white balance. There is no gray card, therefore the camera has to guess, based on

                    assumedly neutral objects or on elements in standard scenes like faces, houses, sky, clouds etc.

                    I read in the book R.W.G.Hunt The Reproduction of Colour, that averaging the whole image could

                    be used as a reference if nothing else is available (Filter > Blur > Average).

                    For me it's not surprising, that any automatism which is based on assumptions leaves something

                    to be adjusted manually.

                    Sorry for not being able to clarify the issue further.

                     

                    Best regards --Gernot Hoffmann