Art....Band

This is the discussion thread for the September 2010 Class.
mikemeister_admin
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Postby mikemeister_admin » Thu Sep 30, 2010 2:34 pm

If I have this right and I am reading it right, then like I said in an earlier post, there isn't anything wrong with this picture.  The RGB in the highlight area, the shadow area, and the neutral area are all where they are supposed to be, and the flesh area is right between the "r" and the first line that separates the "r" from the "y".  These RGB values are all within a few points of each other, so what is there to adjust?  Do I have this wrong? (which is most likely.)
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ggroess
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Postby ggroess » Thu Sep 30, 2010 3:53 pm

Art,
Part of the process is you needing to actively look around for trouble...

Just like you can shop around for a shadow or highlight; you can shop around with a hue clock to "check" for trouble.  If I start in an area that looks good and I do not move around I would not find the hue clocks as shown in my screen shot...

For me the trouble is a blue shadow on the street; and face shadows being too red.  The highlights look good so far but as I adjust the problems out of the image...I might create a highlight problem so I set a hue clock to keep an eye on the highlights.

Greg
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mikemeister_admin
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Postby mikemeister_admin » Thu Sep 30, 2010 4:07 pm

Hmmm....okay, but if you shop around for problems and make adjustments to correct those problems, then won't the non-problem areas adjust themselves into problems?  That is, if the areas that were fine change because you adjusted to correct a different area, then wouldn't the areas that were fine change and no longer be fine?

ggroess
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Postby ggroess » Thu Sep 30, 2010 4:13 pm

That depends on the specific image but.."in general" you'll find a uniform color cast on images...For instance in the case of the drummers; you can see the shadow is blue...If you remove the blue from the shadows you will remove some of the blue from the faces.  It might not be enough but it will effect it...In RGB this is based on Brightness. 

In LAB well you get 1 neutral and you "bet the image on it". Back to RGB; if the color I adjust is in the shadows and I control the curves; like we did with the Blue numbers...then the color adjustments stay only in the shadows...Controlling the curves means add points that bring the curve back to the mid-line.

Greg

mikemeister_admin
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Postby mikemeister_admin » Thu Sep 30, 2010 4:41 pm

I don't follow you here.....I thought that we placed a hue clock in the darkest spot to set the shadow.....another hue clock in the whitest place to set the highlight, and a hue clock in a gray spot to set the neutral.  Why would you place a hue clock in a person's shadow if that spot isn't any of the above places?

I tried it and it worked to get the clocks aligned, but I don't follow why you would use a person's shadow to set the hue clock.  Here's the picture with the hue clock set in the shadow and the blue curve adjusted.

One other thing that I don't understand is why you'd say the flesh tones are off.  The sun is obviously rising, since the shadows are long, and at that time, the sun is very bright.  That intense sunlight is going to make their faces white, so there isn't any good place to locate a hue clock except on the guy's face where I put it.  If you place the clock anywhere else, you will be reading either the bright sunlight, or the shadow areas which can be red, but that's how it should look.  If you try to adjust the red out of their faces by setting a hue clock in the shadow areas of their faces, you end up with an unnatural look. (well, I do. :))
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mikemeister_admin
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Postby mikemeister_admin » Thu Sep 30, 2010 5:02 pm

I've been playing with their flesh tones, and I still don't see any problem.  In my samples, in the hue clock on the girl's face, the red is at 12 noon.  In the guy in the background's face, the red is at 1 o'clock.  The guy in front shows the clock where it's supposed to be....at 12:30.  If you make adjustments to get the girl's clock to read 12:30; you will increase the other two clocks in the wrong direction.  If you adjust the hue clock on the background guy's face, you you will move the other two clocks too far in the opposite direction.  Making no adjustments to any of the clocks is the happy medium.

By the way, what do you adjust to move those clocks anyway.  There is no yellow in RGB, and one clock says there is too much yellow, another clock says there isn't enough yellow, and one clock says there is the correct amount of yellow.  What do you do?

ggroess
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Postby ggroess » Thu Sep 30, 2010 5:02 pm

But Art...You have corrected the faces as well...

In my attached shot your hue clocks have X's in them to separate them out.  Your Face clock is correct and so are the shadows.  The man on the left is fair skinned and his face is a bit too hot but for the purpose of getting this corrected you have done it...the shadow is much better...A touch off but acceptable and the skin tones are "real"  not so far to the left of the 12 hour on the hue clock. 

RE: Shadow areas of the face
But if the sun is lighting both the highlight side and the shadow side they should have the same hue unless there is a really strong reflective surface nearby; and in this case there clearly is not...

If I shoot a picture in the studio and I use a single light source the hue of the skin should not change because the lighting drops off for the shadows..the tone will change but not the general hue value. the Shadow Hue should be reasonably close to the highlight hue.  Sample errors will cause slight differences but they are acceptable in general use...

Great work...really I'm glad you are getting this so far... ;D  ;D  ;D

Greg
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ggroess
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Postby ggroess » Thu Sep 30, 2010 5:04 pm


By the way, what do you adjust to move those clocks anyway.  There is no yellow in RGB, and one clock says there is too much yellow, another clock says there isn't enough yellow, and one clock says there is the correct amount of yellow.  What do you do?


The fastest answer is that blue is the color opposite of yellow.  So if you need more yellow you need to subtract blue....
Go slow on that one as you can get a yellow cast very fast...It might be a very slight adjustment you are looking at...

Greg


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