Help Selecting Lightness Ranges

[PSD]

I want to create selections which will target pixels based on their lightness values. This seems like it should be a simple task but I'm plain stumped.

My goal is to create an action that will assign lightness-based Layer Masks (that only target specific ranges and exclude all others) to Hue/Sat Adjustment Layers for awesome color control.

Specifically, I'm trying to select these ranges:

Highlights: Only pixels with lightness values between 1% and 14%.
Lights: Only pixels with lightness values between 15% and 28%.
Light Mids: Only pixels with lightness values between 29% and 42%.
Midtones: Only pixels with lightness values between 43% and 58%.
Dark Mids: Only pixels with lightness values between 59% and 72%.
Darks: Only pixels with lightness values between 73% and 86%.
Shadows: Only pixels with lightness values between 87% and 100%.

Does anyone have some ideas?

I developed the idea based on the HSL and Tone Curve controls in Camera Raw. In theory, this will allow for better color control than anything currently available in Photoshop or Camera Raw. I would love to make this action available for free online as well as use it in my own workflow!

 

[SCTRWD]

I would do it with 2 adjustment layers. First - Gradient map from black to white. It would turn your image to black and white. The second one - Curves layer. Set units to percents, set input 0, output 0 and input 100, output 0. Then choose pencil and draw correspondent horizontal lines at the upper side of the curves dialog(output - 100): move the cursor to input 1 output 100, click. move the cursor to input 14 output 100, Shift click. And so on with the rest of the intervals.

 

[PSD]

You're brilliant, thank you. I wrote your method in steps for future reference, for people who might happen upon this thread looking for a similar answer.

1. Add a Gradient Map Adjustment Layer going from black to white.

2. Add a Curves layer, map all input values to an output of 0. All pixels will turn black.

3. Still in curves, use the pencil to draw a short horizontal line (by clicking then shift clicking, or by carefully dragging) along the top of the graph, sending only the desired range to white (255).

4. Use the result to create a mask, use that mask to restrict a Hue/Sat Adjustment Layer.

5. Repeat 2-4 for each Hue/Sat layer (do not re-add the gradient map or curves layers). The layers created in steps 1 and 2 can be deleted afterward.

The same process of mapping the histogram to black and then changing short sections to white can be applied to curves where the amount is displayed as pigment/ink %.

 

[SCTRWD]

Actually this can be done with gradient map layer alone. Just add gradient map layer, go to gradient editor, make black to black gradient. Now add white intervals: put white point at starting location of the interval, now add black point slightly to the left of it. Move this black point right over the white one. By hovering it over the white point catch it's position so that there is a sharp turn from black to white. The same way with the end point of the interval, this time put white point at ending location of the interval, add the black point slightly to the right of it and then move it leftward over the white point. Again catch the position which gives sharp transition this time from white to black.

So on with the rest of the intervals. Don't forget to save the gradient

 

[Quantum3]

I think using the posterization adjustment layer is also good. You can divide all the luminosity spectre in specific steps with it.