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-   -   To AttilaLToth: "Accept the challange!?" Yes, sure enough!: (https://www.trekearth.com/forums/showthread.php?t=618662)

Nelu_Goia 05-14-2008 11:41 PM

To AttilaLToth: "Accept the challange!?" Yes, sure enough!:
 
Servus Atti,
I need to make some remarks about your workshop but first I really have to thank you for your time.
OK,no more nice guy!:)
1.First,if there is a major color cast in the photo but not in the highlights or (and) the shadows, you do not go to Lab mode until it`s fixed in RGB,because it is much easier to do it here.If the color cast is uniform all over the picture (which used to happen with the film cameras,but not with the digital cameras,which are worse in this regard),you can take it out fast in Lab.
2.I did not posted a workshop.The one I posted is the original image,without any alteration,so you cannot criticize me for that.
3.If it is to be picky about technicalities,you made some mistakes in the workshop and I can prove it:
-Your gray point on the small camera (number 4)shows me the following readings:R=99,G=104,B=85,which is kind of green,isn`t it?
-Your "white" hat is actually slightly green. The a channel (in Lab) measures between -2 and -5.In my case it shows 0 and -1.
-The worse is your shadow areas,which are totally plunged in (they measure 0,0,0),and it`s not just the watch wrist.
"Color by the numbers",right?:)
-The hand color is more correct in your version,though...
Thanks again,
Nelu

AttilaLToth 05-15-2008 06:41 PM

Colors by the numbers and more ...
 
Hello my friend!

You're welcome - however I'd say the benefit of learning is on my part. :)

My screenshots are there now too.

About my workshop:
I spent some time investigating the original jpeg - by numbers, eyes and even brain mind you ;).
I poked around with rgb, cmyk and lab (every picture has 10 channels, right ?) and some combinations of them to get a feeling for the feasible.

About your comments:
1. "major color cast": Doesn't it have a major one ?? Try to reproduce the changes in screenshot 1 - I think it has.

2. "workshop intent": I surely confused my intent with yours :)
But don't mistake it - as soon as it is published it's out of your control and since you allowed workshop posts ... here we go.

3. "mistakes": I measured the points as follows:
1: a=-2 b=1, r=249 g=252 b=249 (cap: slight green)
2: a=13 b=13, r=96 g=64 b=52 (right hand: red)
3: a=11 b=15, r=130 g=99 b=81 (left hand: yellowish red)
4: a=17 b=9, r=114 g=75 b=73 (right thumb: red)

You can count the shadows as the price of the different moves all the more that imho they don't really contain significant subject related infos. Concerning the background the only usefull info there seems to be some colors (the white of the shirt, etc.).

So yes it is based on "by the numbers" and is more than that... (ouch this is toward self-praise now).

Thank you for the good learn so far.
I keep on rtfm-ing :))

See you soon.
Atti


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