Week 1 images

This board is for the March 2009 Curvemeister 101 class.
mikemeister_admin
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Postby mikemeister_admin » Sun Mar 22, 2009 8:46 pm

I'll post my RGB duck image here.  I'll also include a screenshot of Curvemeister; should we do that on a regular basis?

I didn't max out the Wizard's brightness because it looked like I was starting to lose detail in the duck's belly area.

My RGB version doesn't have nearly as much color as does the Lab version, being that I couldn't crank it up with the Color slider as the last step in the Wizard. So I prefer the Lab version.

And to make it worse, when I saved my RGB version to JPEG, it lost even more color, which happens to me often for some reason that I don't understand.

-Jay


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Postby ggroess » Sun Mar 22, 2009 10:27 pm

Jayslu,
Absolutely post as often as you want. 
We prefer a separate posting for each image so that the response and instruction can be directed to the specific image.  In fact it will become a back and forth as we go...

I'll respond to your posting next.

Greg

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Postby ggroess » Sun Mar 22, 2009 10:51 pm

Jay,

Looking at your image i see a slight greenish yellow cast.  since i see you were using the wizard as you should for the first assignment it really comes down to a neutral choice.  As you can see from shot1, your image downloaded and opened in PS the neutral is a bit off.  Shot3 is you original image with a different neutral. 

So...How did you miss the neutral?? 

Well, it comes down to the sample size set in CM or Photoshop for that matter.  When you choose a neutral, highlight or shadow CM uses the default sample size from the CM configuration settings.  I keep mine set to 3 Pixels unless I am doing something specific.  The end result of that sample is actually 3X3 or the average of 9 pixels.  If yours is set to 5, I think that is the default, you are sampling 5X5 or 25 pixels.  There is a lot more information in there than you might want. 1 Pixel would be a very difficult thing to set and would leave you open to the same kind of error.  You would have to hit exactly 1 neutral pixel.

Take a second pass at the image in both RGB and Lab modes, try it with the wizard off.  Right click on the image to set the SHN values and then move the neutral around a bit.  watch the screen closely for subtile color shifts and see if you can get the neutral to be neutral.  In the upper right hand side of the CM window you should see the Hue clock.  Try to find a spot on the band where the RGB values are all equal.  If you are in Lab the A and B need to be 0 for the color to be neutral.

Greg


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Postby mikemeister_admin » Mon Mar 23, 2009 4:20 am

How can I make my default sample size 3x3?  They are always set to 5x5 unless I change them.

You say to find a spot on the band where the RGB values are equal.  I don't understand: won't the RGB values always be equal wherever I put the Neutral pin?

I'm attaching my next attempts.  The Lab seems better than the RGB because in the RGB there is still a fair amount of yellow in the duck's belly.

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Postby ggroess » Mon Mar 23, 2009 6:34 pm


How can I make my default sample size 3x3?  They are always set to 5x5 unless I change them.


In the configuration area of CM you can set the sample size for the default shot1 and 1a. Click on the wrench in shot 1 and you will get the configuration window shown in 1a or you can set the sample size for any given point from the ribbon bar, Shot2.  Make sure the point you want to change for shot2 is selected and then pull down the sample size menu.

You say to find a spot on the band where the RGB values are equal.  I don't understand: won't the RGB values always be equal wherever I put the Neutral pin?


When you place the mouse over a known area that is neutral, the grey band for example, you can find areas that look neutral but the sample might not be quite neutral so the effect is that you do make the point you choose to be a neutral but you introduce a color shift to the rest of the image.  The goal is to find a "reasonable" neutral that makes the image look good. If you have a known neutral like a gray card or a color checker in the image this is a really easy exercise.  You are in fact "Betting the image" to use a Dan Margolis phrase on your choice of neutral.  Subtle color shifts are tough to spot.  There is a video I am posting that might help clarify this issue.
Greg


I'm attaching my next attempts.  The Lab seems better than the RGB because in the RGB there is still a fair amount of yellow in the duck's belly.



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Postby mikemeister_admin » Mon Mar 23, 2009 7:03 pm

My confusion must stem from the fact that I thought the purpose of the neutral pin was to SET a neutral.  Instead, in sounds as if the purpose is to PRESERVE a neutral, keeping it from moving around while other adjustments are made.  Is the correct?

Also, I was able to change my configuration.  I copied all of the settings in your image, including setting the highlight to RGB(4,4,4) and the shadow to RGB(251,251,251).  What is the thinking behind that?

I appreciate your patient explanations!

-Jay

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Postby mikemeister_admin » Mon Mar 23, 2009 7:37 pm

Well I just watched the Honest Neutral Abe video (except for about the last 20 seconds which I couldn't get) and instead of searching for a already-neutral point for the neutral, the narrater (you?) sets three sample points and tries to get them to neutral.  In this case it looks you are trying to SET a neutral, not PRESERVE one.  So I'm still confused about the correct procedure.

-Jay

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Postby mikemeister_admin » Mon Mar 23, 2009 7:55 pm

In this pass, I used RGB mode and used the same procedure as in the video.  I picked three different sample points on the belly and moved the neutral point around until all three sample points were very close to neutral.

ggroess
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Postby ggroess » Mon Mar 23, 2009 8:11 pm

Hi Jay,
The neutral is a real bugger...and your questions are great...keep em coming..
I would say that the typed word is restricting my discussion about this and you have to bear with me....

I would also say YES to both of your questions depending on the image. Setting a neutral is preserving a known one or creating a neutral where we want one. The whole point of the Abe video is the subtle effect the neutral can have on the overall image and hopefully you worry less about absolute numerical neutral and more about overall look and feel..

Setting a neutral is just that. Setting it. End of story...  BUT

If you do not have a known neutral, a gray card or some other standard, you are in fact guessing.  We take objects we know "should be neutral" or "accepted as neutral" and set them as neutral; that is the neutral pin.  This has the effect of getting rid of most of the color cast BUT......

In the case of "The Duck" or Honest Abe it is a close approximation and not a true neutral. In the case of the duck; there are neutral pixels in the leg band to find... The net effect is that the duck in your case picks up a yellow green cast to the feathers.  Abe in my case could be warm, could be cold the effect was dramatic because our mind says "Hey that should be neutral..." and in fact if you stare at it long enough you will accept it as neutral even with a color cast.  

The effect is based in "simultaneous contrast" we accept subtle differences because we expect it...Many good articles about it in books and on the web.

The correct procedure is to set a neutral to get you very close or right on...when in doubt, Check... check... check...The feathers are the give away...Later in the class we deal with multiple neutrals and almost all of the confusion gets worse and then much better...

RGB has a very handy trait in that you can have multiple neutrals based on the brightness. LAB can have only 1 neutral.  You kind of see that in the Little boy mad image.  I wanted the black chair to be "neutral black" but the highlights; I left alone to be the reddish yellow color area..The neutral I created in the shadows of RGB does not necessarily effect the brightest parts of the image.

Remember...Our goal is a good looking image.  If the rest of the image looks great but something we expect to be neutral looks crappy then we have to decide how important the neutral is, or worse is the neutral lit poorly, reflecting a color that is real, or just plain not needed.

There are many images without a neutral....The Bee image in the thresholding examples really has no neutral. You could argue that the blacks on the bee could be neutral black but I cannot be completely certain...

Greg

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Postby ggroess » Mon Mar 23, 2009 8:15 pm

Your duck looks Great...Much better...

Try it in Lab and hit the saturation a bit see if you can make the ducks bill look brighter...It is harder to do in RGB without adding a color cast....

Greg


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