It’s easily possible with MagicPicker! In the Color Temperature Wheel mode switch on Tone Lock and start shifting the slider on the wheel. This option lets you quickly find corresponding colors having the same brightness for lights and shadows or for foreground and background. Or keep the same brightness level across the surface when editing textures.
MagicPicker 4.3 features increased performance with realtime 64 fps refresh rate in CC 2014*, when picking colors and dragging sliders. (Speed is much higher on high end GPUs). New update also features bug fixes and improvements across all platforms: CS3, CS4, CS5, CS6, CC and CC 2014 in Photoshop and Illustrator.
* as it was benchmarked on Intel Core i5 CPU and Intel Iris 5100 Integrated Graphics card in Photoshop CC 2014.2.2.
Press SHIFT while dragging the pointer on the color wheel (or the stripe in the color pane mode) to bring the colors you pick to the same tone. SHIFT activates temporary Tone Lock mode (usually switched on with the button). While moving your mouse MagicPicker will bring all the colors you choose to the same gamma.