The HUE slider in an adjustment layer

[Doc_Pit]

I would appreciate it if someone would confirm or correct my understanding of how the Hue slider works in a Hue/Saturation adjustment.  The image below shows the panel and part of a Photoshop color wheel.

According to Adobe, as I drag the slider, the values displayed in the text box reflect the number of degrees of rotation around the color wheel from the pixel’s original color. A positive value indicates clockwise rotation; a negative value, counterclockwise rotation. Values range from –180 to +180.

Relating the hue slider to the color wheel: 

Assume I have pure red on an underlying layer and I move the hue slider to the right.  I’m dialing-in positive values (i.e., moving clockwise) on the color wheel.  The effect on the underlying layer is to produce a red to orange to yellow transition, again, moving clockwise on the color wheel.  However, the slider indicates that I’m moving toward blue

It seems like I’m adding the complementary colors (on the left of the color wheel) to move pure red to the orange and yellow hues on the right.  Is that correct?  It seems pretty straightforward, but I just want to be sure that really is what’s happening.

[Chuck Uebele]

The Hue slider just shifts the hue to the next nearest color. So, yes, moving the slider to the right will make a pure red more orange, then yellow. You can look at the bottom two bars on the UI to see how the colors are sliding and changing.

[Doc_Pit]

Chuck, thanks.  I was just observing that moving the slider toward the R (blue) changes the colors to orange>yellow.  I know WHAT it does.  Regarding the HOW, my assumption is that PS is adding complementary colors to the original color.  

[Chuck Uebele]

I don't know the actual math behind it, but I don't think they add complimentary colors. If that were the case, the color would shift to gray.

[Semaphoric]

Here's a page that discusses the math behind RGB to HSL conversion: http://www.niwa.nu/2013/05/math-behind-colorspace-conversions-rgb-hsl/ 

[Doc_Pit]

Chuck, yes, of course you're right.  The complementary colors would simply neutralize the original colors.  At least, I'm disabused of my misconception.  Semaphoric, thanks for the link.  That's a nice, clear explanation of that process.  I hate to approach PS by allowing myself to be satisfied knowing that if I move this slider, I get that result.  Thanks, again.