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What do you use LAB for?

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  #11  
Old 07-15-2014, 09:09 AM
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mistermonday mistermonday is offline
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Re: What do you use LAB for?

Quote:
Originally Posted by skoobey View Post
I know what it does compared to RGB or CMYK, I just don't find it useful for much but masking?
In addition to the other uses referenced above:
- The adjustment of skin color using only two numbers (a channel & b channel) as opposed to 3 or 4 in RGB or CMYK. There is a distinct relationship between the a and b values and a specific range in which almost all skin falls. Adjustments are fast and efficient.
- Adjustment of Temperature and Tint with only two channels. BTW, those sliders you may use in Camera RAW or Lightroom shift the temperature between Yellow (warm) and Blue (cold) represent the b channel in LAB. Similarly Tint shifts between Green and Magenta (a channel).
- Precision color matching in LAB can be done by matching the Lightness and then applying any color. Yes this can be done in RGB but it can often be easier and faster in LAB.
- D&B can be done in LAB without the color shifts you experience in RGB using D&B Curve Adj Layers.
- Frequency Separation in which the HP layer is fully B&W, no color in it and all of the color is in the LF layer. You can not do this in RGB. There is a 3 layer technique in RGB that separates lightness and color but it is inaccurate and those inaccuracies are very visually noticeable.
- A smart object prepared in LAB Color can very comfortably be nested inside of an RGB file. No need to merge, flatten, or convert the object or layer.
LAB can be an extremely useful tool. It is a color space that forces yus to twist the way we think and work. Most people are not very comfortable with it. You can almost always find a way to work without it and reach your image editing destination without it.
Cheers, Murray
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  #12  
Old 07-15-2014, 12:37 PM
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Re: What do you use LAB for?

Quote:
Originally Posted by mistermonday View Post
In addition to the other uses referenced above:
- The adjustment of skin color using only two numbers (a channel & b channel) as opposed to 3 or 4 in RGB or CMYK. There is a distinct relationship between the a and b values and a specific range in which almost all skin falls. Adjustments are fast and efficient.
- Adjustment of Temperature and Tint with only two channels. BTW, those sliders you may use in Camera RAW or Lightroom shift the temperature between Yellow (warm) and Blue (cold) represent the b channel in LAB. Similarly Tint shifts between Green and Magenta (a channel).
- Precision color matching in LAB can be done by matching the Lightness and then applying any color. Yes this can be done in RGB but it can often be easier and faster in LAB.
- D&B can be done in LAB without the color shifts you experience in RGB using D&B Curve Adj Layers.
- Frequency Separation in which the HP layer is fully B&W, no color in it and all of the color is in the LF layer. You can not do this in RGB. There is a 3 layer technique in RGB that separates lightness and color but it is inaccurate and those inaccuracies are very visually noticeable.
- A smart object prepared in LAB Color can very comfortably be nested inside of an RGB file. No need to merge, flatten, or convert the object or layer.
LAB can be an extremely useful tool. It is a color space that forces yus to twist the way we think and work. Most people are not very comfortable with it. You can almost always find a way to work without it and reach your image editing destination without it.
Cheers, Murray
Thank you so much for your deep insight, I just learned few things I was not aware of, actually, I did not try before in LAP, I guess I had a "narrow" vision for it, Humm! sounds very interesting to do FS in LAP, Why the heck I did not think of it before on my own!

The only problem I have is how to insert it as smart object within the RGB space, logically, it would force converting the entire file to LAP (I am sure I am wrong)

@Murray: How to insert LAP into RGB as smart object without converting the entire file?

Thanks for your insight.
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  #13  
Old 07-15-2014, 01:53 PM
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Re: What do you use LAB for?

Quote:
Originally Posted by Aladdin View Post
Thank you so much for your deep insight, I just learned few things I was not aware of, actually, I did not try before in LAP, I guess I had a "narrow" vision for it, Humm! sounds very interesting to do FS in LAP, Why the heck I did not think of it before on my own!

The only problem I have is how to insert it as smart object within the RGB space, logically, it would force converting the entire file to LAP (I am sure I am wrong)

@Murray: How to insert LAP into RGB as smart object without converting the entire file?

Thanks for your insight.
No, there is no need to convert the entire file. Here is an example of the process.
- open a file and go to a layer that you wish to work on. In the example linked here, I just did Ctrl J to duplicate the background.
- Right click on the layer and from the context menu select "Convert to Smart Object".
https://www.mediafire.com/convkey/64...0doomlb46g.jpg

-You will see the following dialog box:
https://www.mediafire.com/convkey/b6...hw1wpamd6g.jpg
This is an important message. The layer is converted to a Smart Object. You can work on it and do anything you want with it in any color space or add layers, D&B, FS split or whatever you would normally do. When you are finished working on it, you click the close window X, you will be asked to save changes -MAKE SURE YOU CLICK THE SAVE BUTTON.

- In this simple example I performed 3 steps. I did Image > Mode LAB Color. The Ctrl % to select the b channel. Then Ctrl I to invert the channel and Ctrl2 to reactivate the composite view. It looked like this:
https://www.mediafire.com/convkey/b8...2rxytm7b6g.jpg

Next I clicked the close window box and when the dialog came up I hit the save button.
You are then returned to your original file. You have your background and then you will see your Smart Object layer. The SO is nested inside your main RGB image and it remains in LAB color.
https://www.mediafire.com/convkey/3e...5z72s9376g.jpg

BTW, you can have as many nested Smart Objects as you like within the layer stack and you can have nested Smart Objects inside of other Smart Objects. You can mix all the color spaces you like.

Cheers, Murray
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  #14  
Old 07-15-2014, 02:04 PM
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Re: What do you use LAB for?

Ouch, I prefer the before image, not that it can't use some work.
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Old 07-15-2014, 02:05 PM
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Re: What do you use LAB for?

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Originally Posted by andrewrodney View Post
Ouch, I prefer the before image, not that it can't use some work.
Ctrl +I
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  #16  
Old 07-15-2014, 02:08 PM
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Re: What do you use LAB for?

@ Aladdin,
If you are interested in performing a Frequency Separation in LAB and want the Color completely separated from the texture, follow my tutorial at the link below. FYI, the HP layer is created using the Apply Image command which produces better results than Filter>Other>High Pass.
http://www.mediafire.com/download/5u...orial_MM++.zip
Cheers, Murray
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  #17  
Old 07-15-2014, 03:12 PM
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Aladdin Aladdin is offline
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Re: What do you use LAB for?

I just gave it a test drive, it works DUH!
Thing is, I use smart objects all the time, somehow, it never "clicked" with me to switch color space within smart object!

Sometime, I spend considerable amount of time in LAB, it used to be frustrating to not being able to fine tune it afterward, This is a life saver step!

Thanks Murray for the walk through, thanks for speedy reply!
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  #18  
Old 07-15-2014, 03:14 PM
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Re: What do you use LAB for?

@mistermonday, thanks for the FS tips and file. Very appreciated.

Alan

P.S. As Natalia loves to say....High Pass SUX!!!!

Last edited by Aladdin; 07-15-2014 at 03:20 PM.
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