Topic: Interactive Hue Clock

[Lee Harper]

New CurveMeister users often mention that it is difficult to know how to adjust their Curves in response to the information presented by the Hue Clocks.

I think that if users could grab the 'Hand' on the Hue clock with the mouse, and move it around the Hue clock to the desired location, this feature would be 1) more intuitive for new users, and 2) make the Hue clock even more useful.

I am envisioning that the UI look somewhat like the screenshot that I have attached, and that when users move the clock hand CM will automatically create/move control points in the Curve panel to change the color. By adding control points rather than changing the color behind the scenes, new users would quickly learn how to translate the Hue clock display information to the curve controls; and more advanced users could further tweak the curve points added/moved to finesse the results.

If nothing else, this functionality would dramatically speed up a lot of corrections.

What do you think?

Lee.

[curvemeister]

I think it's a great idea, and one that I will seriously consider adding to CM4.

When adjusting the Hue clock, it helps to imagine a piece of string between the end of the hue clock and the name of the channel that I am tweaking.  For example, to rotate the above hue clock clockwise, adjust either the Y, R, or M channel.

[Lee Harper]

Hi Mike,

I'm glad that you like the idea

The piece of string visualization is very helpful, and I do use that when I'm color correcting; the trouble is that as a new user I don't think that the 'piece of string' concept occurs to everyone - speaking personally, I had to be told about that in order to understand how to move my curves in response to the hue clock readout.

I would love for CM4 to have a feature that made new users feel as though their understanding of curves and color correction had gone from beginner to intermediate the first time they used the tool; a tough proposition I know, but this might receive an enthusiastic response. Speaking as a digital photography/post-processing teacher, I know that my own students would love this!

All the best,
Lee.

[sjordan93436]

I also think it is valuable to be able to change the hue (saturation) directly of a point in RGB color.   If I want to change the hue, I would rather change one slider or hand than trying to balance three curves.     

Which interface? Click on hue clock and three sliders open (HSB) with original and current values.  Or click on the hand and move it.  I like sliders.  At least these sliders are more powerful than temperature and tint of ACR.

The "free" alternative is what exists.  Mark the spot, go to each curve and move it watching the hue clocks.

[Greg Groess]

Steve,
Lee and Mike are talking about a new user interface for CM4 ..POSSIBLY....

Greg

[Lee Harper]

Hi Steve,

Nik Software use an interface like the one you describe (slider-based). If you've not used any of their software before, they have a good overview of their approach at: www.upoint.com.

Personally, I'm not certain that an updated Hue Clock ought to allow users to manipulate tonality - it is a 'Hue' clock after all. I would envisage that it would enable users to change the Hue and/or Saturation of the color it is pinned to - and if somebody wanted to change Hue and Saturation, if the UI is slider-based then it requires two adjustments; if the UI is more like the one I have suggested, then the same thing could be accomplished in a single move (pulling the end of the hand on the clock).

As you mentioned, an interface that balanced three curves for you - without requiring you to touch them - would be useful. For new users, the visual feedback that they would receive would make curve-based color correction comprehensible much more quickly; advanced users would also benefit from the speed of adjustment - though they would presumably further adjust the curve points that these Hue Clocks would create.

In terms of workflow, I would think that something like this would be likely:

• Set Black point
• Set White point
• Set Neutral point(s)
• Add Hue Clock(s) to critical areas within an image (skin tones, sky, grass, fruit, etc)
• If the Hue Clock(s) indicate a problem, drag the clock hand around the clock (color wheel) to correct problem
• Optionally, manually adjust the control points that are created automatically (during step 5), in the Curves palette

I think that such a workflow would enable even beginners to achieve very good corrections in less than 30 seconds...

Cheers,
Lee.

[Greg Groess]

I could also see it messing up an image in Say 30 Seconds...

Lee,
Do you think...I am asking now...Do you think the image of the fruit vendor window from the class would be easily corrected by hue adjustments?? 

I'm thinking that since the Hue curve "points" would represent all pixels with the selected Hue you could spread the color cast out over different brightness areas.  So for instance...If you have the same hue and sat but a different brightness you are going to change the pixels regardless.  This might be a very bad thing....I could see shadow casts getting very ugly very fast.

While HSB has it's strengths; it has it's Achilles heels as well.  We have to be careful we do not think in RGB while in the HSB realm...You might want to think more like a LAB space just to keep the issues related...changing the hue might not be a good thing on images with crossing casts.

Greg

[curvemeister]

Lee's "HSB Hybrid" workflow really struck a chord, and I think Greg points out some valid concerns.  This workflow could be tested by setting up some Hue only constraints in HSB mode, either by editing the Hue values manually (in the edit dialog), or via the H curve, then switching to RGB mode to see what the result is.

What Greg says is true, with a wrinkle.  In HSB and Lab mode all hues would be affected equally when the hue clock hand is dragged.  In RGB, the hue change would affect areas with those particular R, G, or (emphasis on *or*) B values.

[Lee Harper]

I don't think that any approach would allow the fruit vendor image to be easily corrected

The beauty of what I have in mind (not that I can take any credit for it - I just noticed some other apps doing similar things...) is the connection between this Hue/Sat control and the sample pin.

You are absolutely right - if the curve points were being added to a Hue and/or Saturation curve in HSB everything's going to get messed up; as you said, casts will be introduced over different brightness areas.

By using the location of the sample pin, Hue/Saturation adjustments can be restricted to the appropriate brightness range.

E.g., if I add a sample pin to a brunette's hair, and the Hue Clock indicates that the person's hair is purple, an interactive Hue Clock allows me to grab the clock hand and pull it clockwise; the sample pin tells CM the average brightness of the sampled pixel(s), and control points are added to the curves that the user currently has open (RGB, Lab, or CMYK - you're right to mention that nobody should attempt this in HSB).

The control points would be placed at a location that maintained the brightness of the sampled area (something with an L value of 50 before a Hue/Sat adjustment would still have an L value of 50 after the adjustment).

Intermediate/advanced users would then presumably adjust the control points that the interactive hue clock adjustment had created, to finesse the correction.

What do you think?

Lee.

[Lee Harper]

Mike,

Hadn't thought that it wouldn't work properly in Lab good call on that...

So (more complicated - sorry), the location of the sample pin could be used to create a localized mask (exactly like Photoshop's Select > Color Range command); that would fix that problem I think...

Thanks for the feedback,
Lee.

[Lee Harper]

Of course, if CM had to create localized masks to make this work in Lab, the control points would only be meaningful if CM allowed users to create multiple sets of curves without having to close/reopen the plug-in;
Is that a problem that only a standalone application could fix - or could you allow curve 'layers' within the Photoshop plug-in architecture?

So, two solutions:

• Automatic localized masks when in Lab, CMYK, or HSB
• Control points are only added to a user's curves if they are in RGB

I would prefer a solution that created adjustable control points, because it would be 1) a better learning tool for new users, and 2) more powerful for intermediate/advanced users - but obviously, from a coding point-of-view, the more powerful solution would be more time consuming to code.

Lee.

[curvemeister]

It's actually RGB that is more vulnerable to global effects of hue changes, not HSB and Lab.  As an example, changing the hue of an object whose color is RGB(128,128,0) would change the values of any pixel with a red value of 128, green of 128, or blue of zero.  So, for example, black objects would turn blue, and neutrals would  (oops, gotta catch a plane!!)

[Greg Groess]

Mike is flying off to a Scuba vacation...Seriously South....
So..For the next two weeks you are stuck with me    and no new builds of the plug-in. 

Mike will most likely try to check in <his usual pattern> but do not count on it...
This is a great discussion and I know he wants it to go forward...

Greg

[sjordan93436]

(Warning.  I am wayyyyy  overrrrr my head.  You guys are much better.)

From a beginner point of view..  Let me go through a narrative.

(me talking to myself)
I open a photo in PS or PSE.  (Hmm....  the faces look bad and the sky too.  )

Open CM, use RGB color space. 

Alt click a hue clock on the face and sky.  (Hmmm...  Where should those hands be pointing?)

Open hue face adjustment box- about 2 or 3 inches square.  Click on dialog box for pin target.  Select "skin"

(hmm.  the hand points to 1:30 and is 95 units long, CM says it should be somewhere around 12:30 and 60 units)

Grab the hand.  Move it left and inward toward the suggested area.  Release.  All three curves move (R,g,B) Skin clears up. There is a control point on all three curves.  It is labeled "Skin 1".   

(hmm not bad but if I move it around within his suggested box, it might be better).

Using cursor control, I tweak the points and curves.  (hmm.... not bad, what next)

(hmm..  the skin seems dark)  Bump up the luminosity slider.  All three curves move again.

Do the same for the sky, the neutrals, shadows, highlights, greenery.  (hmm...  oops, too many points and the curves have kinks.)  Manually adjust curves.

________________

Experienced or advanced users do not require this crutch, but it might help newbies.

Every point in the RGB color space has a HSB value.  Every HSB value has an RGB value.  If you move the hands of the clock from one HSB value to another HSB value, the RGB value changes.  If you change the values of a point, then one, two, or three curves move.  This is what "pinning" does. 

Mike is right.  If you drag a HSB point, it gets weird around 12:00 noon (red).   The curves go strange.

If I garbled this up, just forget this post.

[Greg Groess]

Steve,
You have described a work flow..That is just fine with some conditions....
The real trouble is that when you start adjusting based on a hue or any other point you move entire sections of the curve.  This has implications when you switch back to RGB from the HSB adjustment or convert it on the fly...

Your questions are valid...What color should the sky be...you can sample 100 sky images and get 100 different answers from almost white to a deep indigo and frankly any color in between including Green...

Grab the Hue hand...Well that is where the discussion is currently at...The problem with "grabbing the hand" as it were is that you bring all of the pixels in the image with the same HSB value with you when you adjust not just the local area of the image that you want to fix.  Yes they relate to an RGB pixel but many times there is not an exact match...There is some math in the mix that can make a mess of this...<Mike's bag  of tricks not Mine>  and as Mike started to describe...If you have a point that is (128, 128, 0) in RGB and you "grab that point and move it...to say (128,128,128) all of the B values that are 0 will move to 128 across the entire image...if I read his logic right...<Actual verbiage missing and slightly guessed at...> 

There is a program out there that Art told us about in the last class...it's an older program and well I don't quite remember the name but it allowed similar adjustments.  Trouble was it had limits...

I'll see what I can dig up from the last class...

Greg