7 Replies Latest reply: Oct 19, 2013 5:04 AM by c.pfaffenbichler RSS

    Using Eyedropper with Curves

    media kat Community Member

      When using Curves to increase contrast for an image, I see that some people will use the eyedropper to define an anchor point on the Curve to manipulate, and others just seem to drag on a spot on the curve without first using the eyedropper.

       

      1. Is there a reason to not use the eyedropper, and instead just drag a point on the curve?

      2. Won't using the eyedropper always be more accurate than just eyeballing a spot on the curve to drag?

       

      Thanks in advance.

        • 1. Re: Using Eyedropper with Curves
          c.pfaffenbichler Community Member

          1. Is there a reason to not use the eyedropper, and instead just drag a point on the curve?

          With experience (and preferably a calibrated monitor) it may be possible to judge which luminance region one wishes to edit approximately.

          And dragging a Curve point will elicit visual feedback that allows to correct the editing anyway.

           

          2. Won't using the eyedropper always be more accurate than just eyeballing a spot on the curve to drag?

          »accurate«? With regard to what?

           

          You make no mention of Adjustment Layers – do you apply Curves destructively?

          • 2. Re: Using Eyedropper with Curves
            media kat Community Member

            "

            »accurate«? With regard to what?

             

            You make no mention of Adjustment Layers – do you apply Curves destructively?"

             

            I am using an Adjustment Layer. I guess with regards to "Accurate" it is somewhat subjective as to what makes good contrast for an image? Two people wouldl ikely end up with slightly different results anyways, right?

             

            In CS6, I start with the white eyedropper and select a white area on my image expecting it to also plot an anchor point for the value I selected, however, it did not. I also tried with the black eyedropper and selected a dark area of my image and it did not plot an anchor point on the curve either. Does it not work this way?

             

            Thanks.

            • 3. Re: Using Eyedropper with Curves
              c.pfaffenbichler Community Member

              I am using an Adjustment Layer. I guess with regards to "Accurate" it is somewhat subjective as to what makes good contrast for an image? Two people wouldl ikely end up with slightly different results anyways, right?

              If you were to provide the same image to two image editors and instruct them to improve the contrast I suspect seldom would you get the exact same result from both.

               

              When setting the White Point the values (or the closest ones feasible) at that point should be set to output zero.

              Could you please post a screenshot with the pertinent Panels (like Layers) visible?

              • 4. Re: Using Eyedropper with Curves
                media kat Community Member

                Here are the photos (cropped to remove a person). The image originally had a yellowish orange color cast. There is only the background layer and the adjustment layer.

                - when I use the white eyedropper to select some of the white fur, it seems to remove the color cast, though it is not plotting an anchor point on the curve for me to manipulate, and it is also displaying the R,G,B curves as well

                - when I use the black eyedropper to select black fur in the image, it darkens the image, but still does not display an anchor point on the curve

                 

                Thank you for your help

                Screen Shot 2013-10-17 at 9.43.35 AM.pngScreen Shot 2013-10-17 at 9.43.50 AM.pngScreen Shot 2013-10-17 at 9.44.59 AM.png

                • 5. Re: Using Eyedropper with Curves
                  c.pfaffenbichler Community Member

                  And that is what the white and black point eyedroppers are supposed to do.

                  If you want to set a point on the composite curve set the Properties Panel to »Auto Select Targeted Adjustment Tool« and click in the image.

                  • 6. Re: Using Eyedropper with Curves
                    media kat Community Member

                    1. Is the idea that you might use the eyedropper tool to set the white and dark values and not need to adjust the points on the curve or the curve manually?

                     

                    2. I just enabled that setting in the menu for the curves properties, though it is not placing anchor points on the curve after using the eyedropper to click on different colors in the image. It just seems to be moving the R, G , B lines when I click different areas.

                     

                    Thanks.

                    • 7. Re: Using Eyedropper with Curves
                      c.pfaffenbichler Community Member

                      I may have misunderstood what you are talking about, so I’ll try to clarify:

                       

                      • You need not select the Eyedropper Tool from the Toolbox to edit Curves Adjsutments.

                      • The White and Black Point Eyedropper are intended to define points in an image as white and black. That means the values of that point are made 0 and 255 respectively if they are not close to opposite extremes already.

                      This can be usefull in badly exposed or faded images or scanned images on a darkish substrate when one wants to increase the contrast or when editing Masks based on channels from images.

                      • In the old modal dialog (which I stil use) command-clicking in the image would create a corresponging point on the curve.

                      If the non-modal former Adjustments -, now Properties Panel is set to »Auto Select …« selecting a Curves Layer should change the cursor to an eyepicker symbol and simply clicking in the image should create a pont on the Curve which can be moved manually or with the arrow keys.

                      And click-dragging should create the point on the Curve and move it vertically.