Author Topic: Quickie: % readout for RGB spot meter  (Read 6510 times)

PhotoCat

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Quickie: % readout for RGB spot meter
« on: October 20, 2014, 06:39:59 AM »
Hello ML team,

Is it simple to add a % readout option to the RGB spot meter?
Right now it is hEX: e.g.  CDBFB1
It would be nice to be able to display %R %G %B.   e.g. 80%, 76%, 70%. 
This way one can tweak skin tone easier in camera, similar to using lightroom % display.
Thanks!

Audionut

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PhotoCat

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Re: [ALEADY DONE... not really] Quickie: % readout for RGB spot meter
« Reply #2 on: October 20, 2014, 07:38:20 PM »
Thanks for your reply Audionut once again.
Yes I know percentage has been implemented but it is for luminance only.
It is not for RGB. We need 3 separate percentage numbers.  :)
Thanks :)

Audionut

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Re: [ALEADY DONE] Quickie: % readout for RGB spot meter
« Reply #3 on: October 21, 2014, 01:47:15 AM »
Can you explain further the usefulness?  Considering it would only be valid when shooting JPG, I doubt anyone would bother to implement it.

There's always the vectorscope.

PhotoCat

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Re: [ALEADY DONE... not really] Quickie: % readout for RGB spot meter
« Reply #4 on: October 21, 2014, 03:48:47 PM »
RGB % spot meter can be used to obtain a rough start on WB/WB-shift  for a pleasing skin tone in camera!

The current RGB meter gives a non-intuitive HEX number e.g. CDBFB1
It is much more intuitive to have the % value displayed like Lightroom: e.g. RGB: 75% 65% 55% (a good start for  caucasian skin tone)
"Here is one basic rule of thumb for average skinned caucasian: 20 points difference between R & B with G as close to the middle as possible. Example 75% R, 65% G, 55% B. For darker skin, numbers will be higher, for more yellow in skin, decrease blue value, etc."

I know by shooting in raw, one can tweak WB for skin tone in post but that would be time consuming.
Same thing for exposure as I don't use auto exposure because it will over or under expo skin depending upon background tone.
The best photographer is able to get everything right in camera!  With ML, it is possible.

I hv tried using the vectorscope to tune in skin tone but I never find it reliable looking at the 135 degree clusters. Perhaps I don't know how to use it correctly??

Pls see this article for reference about the application of % RGB values to correct for skin tone in Lightroom.

https://forums.adobe.com/thread/830740?tstart=0

Quotes:
Q: "That depends extremely heavily on the particular person's skin.   Use a good white balance approach instead."
 
A: "Definitely agree, but there are some very basic estimates that can help get within the range. Then use your eye & a well balanced monitor to tweak and perfect.
 
Here is one basic rule of thumb for average skinned caucasian: 20 points difference between R & B with G as close to the middle as possible. Example 75% R, 65% G, 55% B. For darker skin, numbers will be higher, for more yellow in skin, decrease blue value, etc."

dmilligan

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Re: [ALEADY DONE] Quickie: % readout for RGB spot meter
« Reply #5 on: October 21, 2014, 04:12:23 PM »
I know by shooting in raw, one can tweak WB for skin tone in post but that would be time consuming.
I would argue that tweaking WB in camera is much more time consuming than doing it in post.

PhotoCat

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Re: [ALEADY DONE... maybe not] Quickie: % readout for RGB spot meter
« Reply #6 on: October 21, 2014, 05:55:59 PM »
"I would argue that tweaking WB in camera is much more time consuming than doing it in post."

It may be so using a bare canon SLR but definitely not so if ML provides the tool to do it. :)
I agree if things are happening randomly & u need to capture whatever pops up in your face,
u just shoot and forget about setting WB. However, for events and model shoots, u can afford
about 30sec's  time to set correct WB and forget about that half an hours WB tweaking in post. I think that
is a good investment.  Well, if u count the LR pic loading/exporting time and 1:1 rendering time, it saves much more time
than u think.

For my shoots, I usually can post my pics the same day as the shoot, because my jpgs are correct directly
out of the camera and I don't need to go into a raw converter for 95% of my shots.

Hv u tried WB shift bracketing in camera? U take 1 pic and only 1 pic and the camera would give u
3 jpgs with different WB to choose from.  At the same time, I know ML can display "tweaked exposure" during LCD
playback using the thumb dial.

By combining the above ideas,
what would be handy for ML to do is that, during playback mode,
ML would give us 2 dials to tweak WB exactly the same way as the 2D WB-Shift. At the same time the RGB spot meter (in %)
would get updated upon the 2 dials. (one dial for Blue-Amber shift and another for Green-Magenta shift).

This way, skin tone WB can be set quickly:  (u know all subsequent shots will hv good skin tone)

1) Take one pic of the person under that particular lighting with the best guestimate of WB/K setting and exposure.
2) Playback the portrait and activate ML Live 2D WB-shift.  (I think K can be adjusted in liveview too, not sure about WB-shift)
3) Point the RGB % spot meter on the face
4) Rotate thumb dial and main dial to weak WB until u see a pleasing skin tone or until the RGB % spot meter gives u a good value.
5) Press a button to register that 2D-WB-shift into the camera.
6) Done!

Note it is not always possible to use a grey card, nor would grey card always give u the most pleasing skin tone.










PhotoCat

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Re: [ALEADY DONE... maybe not] Quickie: % readout for RGB spot meter
« Reply #7 on: October 21, 2014, 07:01:44 PM »
Wow, I have discovered a gem in ML in setting WB & WB-shift in liveview!  It is there now!
This is vy close to what I want :)

for 5D2
1) go into liveview with ML spot meter activated
2) press the WB button on top of camera
3) now use the thumb dial to select k
4) point the centre of the LCD to a grey object, (u may use x5 or x10 zoom to select
a small grey object!!)
5) press set button
6) It is automatically setting K & WB-shift based on what is inside the box in the centre!!
7) u can double-check the WB setting by reading the RGB spot meter to see if R=G=B (though not in % unit)

Wow! Kudos to whoever implemented this hidden feature in ML!!  It is there today and my ML version is nightly build end of March 2014 or so.
So this is vy useful I can see, if u don't have a grey card handy or u can't go up the stage to set a custom WB!
With this feature already in ML and it is working with the spot meter too! 

So all I need is the ability to manually fine-tune the WB-shift in liveview using the 2 dials, the same way as adjusting K in liveview.
Of course a % RGB readout would be essential in checking the skin tone.


Would this be possible to do in ML?   Thank you!


PhotoCat

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Re: [ALEADY DONE...maybe not] Quickie: % readout for RGB spot meter
« Reply #9 on: October 22, 2014, 12:20:05 AM »
Thinking about it more, live view WB really doesn't work when flash/gelled flash is used.

So RGB % spot metering on skin area becomes vy important when it comes to WBing  skin tone when flash is used.

In such a case, ideally, one will have to take a shot and then look at it in playback and tweak the 2 dials (B-A) (G-M) to get
a good skin tone % RGB number on the face.  Alternatively, one will take a shot with the grey card with flash, and WB on grey card.
This should bring the image closer to the final result.
With the image on playback, one can tweak the 2 dials to come up with the most pleasing skin tone..

Either way will take more effort to implement in ML I guess.

For now, it would be very useful to just hv the RGB % spot meter and skin tone can be tweaked  the old fashion way.

Thanks!