Slowly I'm beginning to get the impression that "bug" is the word for "user error" or "user inexperience" in your language.   

You're looking at colors in the histogram because that's what you have chosen in the dropdown:

Here's what you see if you set the Channel dropdown to Colors:

and here's what you see when you set it to Luminosity:

As you can see, there are other choices, such as RGB and individual channel, six selections in all.

Next time you feel like crying wolf—or bug—reach for the Help files in Photoshop instead.  You might also want to buy a good book to learn Photoshop, mantralight.  I'd recommend "Photoshop Clasroom in a Book".

LOL !    We're getting lost in words here.

What is funny is that the answer to your question, exactly the way you phrased it, is YES.  I  am indeed saying "that even if for example you set the dropdown to read RGB it doesn't stay set when you restart photoshop or even just open another document".  But I suspect that is the opposite of what you intended to express. 

Re-reading your original post, I see now that what you are complaining about is the fact that the choice of setting is not "sticky".  That being the case, then what you have there is a feature request, but that is hardly "a bug". 

You should post that request in the feature request section.  But if it bothers you that much, you can just record an action of the simple process of selecting the desired choice in the dropdown and then assign the action to a key.  That way you can make the selection by simply pressing a key or key combination.

It always goes back to showing Colors for me as well.  I have always assumed that's just the normal behavior.

-Noel

Noel Carboni wrote:

 

It always goes back to showing Colors for me as well.  I have always assumed that's just the normal behavior.

 

-Noel

I thought I was going to be very clever, and suggest creating a New Workspace in which the Histogram was set to Luminosity, but I just tested it and it didn't survive a restart.  The best I could manage was savine a new Workspace with the Histogramm set to All channels view, which does survive a restart. (But not until you load a picture.)   You'd need to be pretty dogmatic about the way you use the Histogram to devote that much screen space to it!

In Photoshop CS6, when you look at a single channel by clicking on the channel name in the Channels panel, that color name comes up in the Channel: field of the Histogram.

But when you click on the RGB aggregate channel in the Channels panel, the Histogram goes to RGB, not Colors.

That it does not go back to Colors does seem a bit inconsistent.

-Noel