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harryn54556073
Participant
October 27, 2020
Question

I have the latest photoshop cc version, I can not select black or white point using threshold layer

  • October 27, 2020
  • 2 replies
  • 2265 views

Hello and good day, I am just trying to use threshold for the first time to edit an astro image.

The video I am watching shows using threshold layer slide the slider in the levels window to

the left to show the black point and select that spot, but does not show how this is done, just too

fast. I tried holding control, or alt and left click right click. what is the trick?

Oh I guess this is not sed much as my searching revieled no usefull answer.

Oh and I am using windows 10 home.

 

Thank You

 

 

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2 replies

Norman Sanders
Norman Sanders
Legend
November 3, 2020

The following is part of a Tech Sheet I wrote for my students. You may find it helpful.

******* 

Step One: Locating the existing extremes of highlight and shadow

 

            From the symbols at the bottom of the Layers panel, select Adjustment Layer (half-black-half-white circle) and from its drop-down menu choose Threshold. You will be presented with a histogram, and below it, a slider. Move the slider all the way to the right; the image will go completely black. Inch the slider to the left until the first white non-spectral patch appears. It is the location of the highlight extreme. Choose the Color Sampler tool. (It is nested with the Eyedropper tool in the Tools panel.) Click in that highlight location. The Color Sampler will mark the site. We will call it Register Mark 1.

 

            Next, move the slider all the way to the left; the image will go completely white. Inch the slider to the right until the first meaningful black patch appears. (Values darker than the one selected will ultimately go to maximum black. Deciding the position of the shadow end point is not a mindless, mechanical process. It is an important judgment call.)  Choose the Color Sampler tool. Click in the shadow location. The Color Sampler will mark the site. We will call it Register Mark 2.

 

            You no longer need the Threshold layer, so drag it to the Trash. The points you marked will remain. You have now successfully located and marked the highlight and important shadow end points.

 

 

    T
    twardlow
    Participant
    November 4, 2020

    Norman when I do as you suggest in seting black and white points with threshold, and I delete threshold layer, and control points or what you call rgister points remain please tell me how to get rid of the register ponts in my final image.  This is driving me mad!  Many, many thanks for your reply

     

    Anyone else want to help?  I'd appreciate it.....tom

    Norman Sanders
    Norman Sanders
    Legend
    November 4, 2020

    In the Tools panel, choose the Color Sampler tool and in its Options Bar click on Clear All.

    (That instruction appears later in the Tech Sheet in addion to the following paragraphs. Perhaps you will find it helpful.)

    *********

    Step Two: Placing our end point criteria in those two areas

     

    Image > Adjustments > Curves

    Click on the Highlight eyedropper; then click on Register Mark 1

    Click on the Shadow eyedropper; then click on Register Mark 2

    You have altered the tonal curves and created a full range image. (An extra goodie: Correcting the end points in this manner often contributes substantially to correcting color balance throughout the image, as it did in the example above).

     

    You may find that now, other areas, perhaps the 3/4 tones, should be lighter or darker. Alter the curve to suit yourself. You may make the adjustments by either clicking and bending the curve or using the TAT (Targeted Adjustment Tool) in the image area. The critical end points, which created the full range image, will not be affected. Last, remove the markers: With the Color Sampler tool chosen, click on the words Clear All that appears in the Options bar. 

     

    One final note about end points: Not all images require meeting endpoint criteria. If the highlights in a photograph are dark or off color or the shadows a bit weak, but you simply like the look of the image, don’t mess with success. Leave it alone.

     

     

     

      J. Stuart Johnson
      J. Stuart Johnson
      Inspiring
      October 28, 2020

      I'm guessing the video tutorial was using a Levels layer and not Threshold. When using Levels, if you holding down the alt(win)/opt(mac), the preview will change to a threshold preview. Giving you a better indication of where the white or black point is located based on the slider value.


      The threshold layer, doesn't do all that much. It only allows you to set an image to a mono black or white image based on the value selecte with the slider. 

        H
        harryn54556073Author
        Participant
        November 3, 2020

        I posted a reply but it is not showing up. Very sorry for that. I will have to find the

        video again, tried today but not finding the one I was following. I thank you for

        your comment. I am finding more info on setting black point so when I have time

        I will look futher.

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