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Author Topic: Colour slider - strange effect  (Read 961 times)

bobtrlin

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Colour slider - strange effect
« on: December 09, 2017, 03:19:10 AM »

Am I colour blind or what?  I took a macro of a green cicada.  Actually it was light green but clearly green to the eye.  On the image it looked a little too yellow so I moved the green slider up.  It did almost nothing.  To try to work out what was happening, I zeroed all sliders bringing the image to monochrome.  I moved the green slider all the way up.  There was only a slight increase in a grey/green colour.  Zeroing everything again, I brought up the yellow slider and lo and behold, there was the green cicada but still a bit yellow.  What is happening here?  Why is the green slider so ineffectual and why is the yellow slider so effective in enhancing green?
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Tony Jay

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Re: Colour slider - strange effect
« Reply #1 on: December 09, 2017, 03:58:31 AM »

Am I colour blind or what?  I took a macro of a green cicada.  Actually it was light green but clearly green to the eye.  On the image it looked a little too yellow so I moved the green slider up.  It did almost nothing.  To try to work out what was happening, I zeroed all sliders bringing the image to monochrome.  I moved the green slider all the way up.  There was only a slight increase in a grey/green colour.  Zeroing everything again, I brought up the yellow slider and lo and behold, there was the green cicada but still a bit yellow.  What is happening here?  Why is the green slider so ineffectual and why is the yellow slider so effective in enhancing green?
Very simple - what you perceive to be green in this case actually has a large component of yellow.
If you are really interested then start investigating colour theory and specifically the RGB system of additive colour.

Tony Jay
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Mark D Segal

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Re: Colour slider - strange effect
« Reply #2 on: December 09, 2017, 07:39:24 AM »

Am I colour blind or what?  I took a macro of a green cicada.  Actually it was light green but clearly green to the eye.  On the image it looked a little too yellow so I moved the green slider up.  It did almost nothing.  To try to work out what was happening, I zeroed all sliders bringing the image to monochrome.  I moved the green slider all the way up.  There was only a slight increase in a grey/green colour.  Zeroing everything again, I brought up the yellow slider and lo and behold, there was the green cicada but still a bit yellow.  What is happening here?  Why is the green slider so ineffectual and why is the yellow slider so effective in enhancing green?


Next, you need to understand the principles of colour opposites and colour components in order to understand colour balance adjustments. Yellow is the opposite of Blue. Green is the opposite of Magenta, and Red is the opposite of Cyan. Green is a mixture of Yellow and Cyan. So in your case, using the colour balance tool available to you, you want to back off a certain amount of Yellow to rid the Yellow cast, which increases Blue and brings out more Green. You do this by reducing Yellow or increasing Blue, same thing. Then, if it isn't Green enough, you could back off a bit of Red to increase Cyan, or increase Cyan, same thing. In your case the use of the Yellow control worked well because the hue of Green in the photo most likely holds a lot of yellow. You may also have a Hue adjustment tool that works on individual colours, in which case you would move the Yellow control toward the cooler end.
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Mark D Segal (formerly MarkDS)
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bobtrlin

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Re: Colour slider - strange effect
« Reply #3 on: December 09, 2017, 05:06:05 PM »

Thanks guys!  So does this mean that the slider that LR labels as "Green" affects only that group of frequencies regarded as pure green whereas what we perceive as green in nature is mostly a composite of yellow and cyan?
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Mark D Segal

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Re: Colour slider - strange effect
« Reply #4 on: December 09, 2017, 05:35:10 PM »

Thanks guys!  So does this mean that the slider that LR labels as "Green" affects only that group of frequencies regarded as pure green whereas what we perceive as green in nature is mostly a composite of yellow and cyan?

Green is ALWAYS a composite of Yellow and Cyan, the balance between the two, or "weights" of the one versus the other, determining the precise hue of Green at hand. If we're talking about the HSL panel in LR, the Hue slider for Green allows you to move the shade of Green toward Yellow (leftward) or toward Cyan (rightward). It will only work if the hue you click on is predominantly Green. If what you are clicking on is predominantly Yellow, then you could use the Yellow Hue slider and it will make Yellow greenish when slid to the right.
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Mark D Segal (formerly MarkDS)
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paulster

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Re: Colour slider - strange effect
« Reply #5 on: December 11, 2017, 02:38:23 PM »

Am I colour blind or what?  I took a macro of a green cicada.  Actually it was light green but clearly green to the eye.  On the image it looked a little too yellow so I moved the green slider up.  It did almost nothing.  To try to work out what was happening, I zeroed all sliders bringing the image to monochrome.  I moved the green slider all the way up.  There was only a slight increase in a grey/green colour.  Zeroing everything again, I brought up the yellow slider and lo and behold, there was the green cicada but still a bit yellow.  What is happening here?  Why is the green slider so ineffectual and why is the yellow slider so effective in enhancing green?
Above each section of HSL sliders there's a little circle with a mark in the centre of it.  If you click on this then you can click on the colour you want to edit in the image and drag your mouse up/down and it'll adjust the relevant sliders for you.  It can be a good way to see which combinations of sliders you need to focus on in order to get the colour edit you need, even if you go back and do it yourself manually afterwards.
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bobtrlin

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Re: Colour slider - strange effect
« Reply #6 on: December 11, 2017, 03:28:44 PM »

I should have been more precise in my original post.  With regard to the HSL sliders, I've never used the Hue sliders simply because I don't understand their action.  However, in view of the comments above I had a go and found that I could substantially increase the green, much more so than increasing green with the S slider.  It was at the expense of some magenta elsewhere but that I could live with.  This still leaves me perplexed but I will experiment with the H sliders more in the future.
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Mark D Segal

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Re: Colour slider - strange effect
« Reply #7 on: December 11, 2017, 03:40:53 PM »

  It was at the expense of some magenta elsewhere but that I could live with. 

When this happens, it may be best to use the Brush tool and make a selection of the green you want to amend, then use the Tint or Temperature sliders on the top of the menu, or the color picker at the bottom of the menu to adjust only the area that you have selected.
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Mark D Segal (formerly MarkDS)
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rdonson

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Re: Colour slider - strange effect
« Reply #8 on: December 11, 2017, 04:24:10 PM »

This color wheel may help
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Regards,
Ron

bobtrlin

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Re: Colour slider - strange effect
« Reply #9 on: December 11, 2017, 06:34:45 PM »

This color wheel may help
Thanks for that!  Saved and printed on a 4x6 for reference.
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