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02/22/2009 01:21:26 PM · #1 |
I've been playing around with LAB alot lately and wonder if anyone has any "tips".
I've been curving the a and b channels to get some interesting results.
before  after 
this example also includes sharpening the lightness channel. |
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02/22/2009 02:17:07 PM · #2 |
i have also been using lab recently.
lab is good for colour alteration, converting to b&w, sharpening and noise reduction!
the shot you have edited in lab is way better!
what did you do in lab mode??
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02/22/2009 10:22:07 PM · #3 |
Originally posted by dainmcgowan:
i have also been using lab recently.
lab is good for colour alteration, converting to b&w, sharpening and noise reduction!
the shot you have edited in lab is way better!
what did you do in lab mode?? |
I did a curves adjust on a and b - I took the upper right marker and slid along the top toward the center about 2 blocks and did the same to the lower left - this "condensed" the output on those channels. |
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02/26/2009 11:14:02 AM · #4 |
Originally posted by Lonz:
I did a curves adjust on a and b - I took the upper right marker and slid along the top toward the center about 2 blocks and did the same to the lower left - this "condensed" the output on those channels. |
I have been doing the same thing. I find that sometimes I don't want to go the full two blocks for both, sometimes I want to go the full on one but not the other. I just fool around until I get the result I like. It is good for boosting the colors. I originally found a link to a tutorial on flickr that showed how its done, but I'm at work right now and can't access flickr to check it-- I think this is the link.
//www.flickr.com/groups/technique/discuss/72057594133492563/ |
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02/27/2009 02:13:57 PM · #5 |
| I can't find an a or b Lightness channel in CS4 Curves. |
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02/27/2009 02:58:53 PM · #6 |
Another is to convert to Lab, then do Apply Image in Soft Light mode. Then choose the channel to apply (usually will be a or b that works best, though sometimes Lab itself works). Lightness is too odd for me in Soft Light).
Then you can adjust the opacity slider.
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02/27/2009 05:08:43 PM · #7 |
Originally posted by HawkeyeLonewolf:
Another is to convert to Lab, then do Apply Image in Soft Light mode. Then choose the channel to apply (usually will be a or b that works best, though sometimes Lab itself works). Lightness is too odd for me in Soft Light).
Then you can adjust the opacity slider. |
Hm. Soft Light appears to block shadows. Where exactly should I find which channel with a and b unavailable? |
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02/27/2009 05:20:49 PM · #8 |
Originally posted by Lonz:
Originally posted by dainmcgowan:
i have also been using lab recently.
lab is good for colour alteration, converting to b&w, sharpening and noise reduction!
the shot you have edited in lab is way better!
what did you do in lab mode?? |
I did a curves adjust on a and b - I took the upper right marker and slid along the top toward the center about 2 blocks and did the same to the lower left - this "condensed" the output on those channels. |
i do this, but to all 3 channels.
i then change the layer to 'color' back in RGB mode.
lab is also a good way to convert to b/w.
deleting all the channels and converting back to RGB (via grey scale) leaves a nicely toned b/w.
for noise reduction adding a median filter in all channels reduces some color noise.
this does slightly de-saturate the image, so boost with a hue/sat layer back in RGB.
Message edited by author 2009-02-27 17:21:30.
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02/27/2009 08:21:36 PM · #9 |
Originally posted by zeuszen:
Originally posted by HawkeyeLonewolf:
Another is to convert to Lab, then do Apply Image in Soft Light mode. Then choose the channel to apply (usually will be a or b that works best, though sometimes Lab itself works). Lightness is too odd for me in Soft Light).
Then you can adjust the opacity slider. |
Hm. Soft Light appears to block shadows. Where exactly should I find which channel with a and b unavailable? |
After opening an image, select Image>Mode>Lab Color.
The L in "Lab" stands for Lightness, and a and b are chromaticity channels (not color channels in any normal sense). Remember to convert back to RGB after making any adjustments.
The conversion to Lab and back is not without potential for loss of information, however if working in 16-bit-per-channel mode, I believe the only real loss will be in color space extents; Lab is smaller than some other spaces, if memory serves. |
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02/27/2009 09:03:12 PM · #10 |
Originally posted by kirbic:
Originally posted by zeuszen:
Originally posted by HawkeyeLonewolf:
Another is to convert to Lab, then do Apply Image in Soft Light mode. Then choose the channel to apply (usually will be a or b that works best, though sometimes Lab itself works). Lightness is too odd for me in Soft Light).
Then you can adjust the opacity slider. |
Hm. Soft Light appears to block shadows. Where exactly should I find which channel with a and b unavailable? |
After opening an image, select Image>Mode>Lab Color.
The L in "Lab" stands for Lightness, and a and b are chromaticity channels (not color channels in any normal sense). Remember to convert back to RGB after making any adjustments.
The conversion to Lab and back is not without potential for loss of information, however if working in 16-bit-per-channel mode, I believe the only real loss will be in color space extents; Lab is smaller than some other spaces, if memory serves. |
Thanks, F. Should I ignore "Lightness" then as well as "a" and "b" while proceeding with curves etc.? |
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02/27/2009 09:24:29 PM · #11 |
Originally posted by zeuszen:
Thanks, F. Should I ignore "Lightness" then as well as "a" and "b" while proceeding with curves etc.? |
Try experimenting... Lab is, well, just different. Try sharpening on just the L channel, for instance. Or try running curves on either a or b, or a combination. Personally, I don't use Lab mode that often, but I have sen some folks get some pretty remarkable results with it occasionally. |
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02/28/2009 12:32:03 AM · #12 |
Originally posted by kirbic:
Originally posted by zeuszen:
Thanks, F. Should I ignore "Lightness" then as well as "a" and "b" while proceeding with curves etc.? |
Try experimenting... Lab is, well, just different. Try sharpening on just the L channel, for instance. Or try running curves on either a or b, or a combination. Personally, I don't use Lab mode that often, but I have sen some folks get some pretty remarkable results with it occasionally. |
Well, yes, I'll experiment, however...
there are no "a" or "b" channels in CS4's Curves. They don't exist. Also No "L" channel, unless you're abbreviating "Lab Color" (Mode)...
? |
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02/28/2009 12:54:12 AM · #13 |
Originally posted by zeuszen:
Originally posted by kirbic:
Originally posted by zeuszen:
Thanks, F. Should I ignore "Lightness" then as well as "a" and "b" while proceeding with curves etc.? |
Try experimenting... Lab is, well, just different. Try sharpening on just the L channel, for instance. Or try running curves on either a or b, or a combination. Personally, I don't use Lab mode that often, but I have sen some folks get some pretty remarkable results with it occasionally. |
Well, yes, I'll experiment, however...
there are no "a" or "b" channels in CS4's Curves. They don't exist. Also No "L" channel, unless you're abbreviating "Lab Color" (Mode)...
? |
Image | Mode -> Lab color
THEN go into curves layer.
There they are... in the dropdown box above the grid. "Lightness" "a" and "b" |
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02/28/2009 11:46:56 AM · #14 |
Originally posted by HawkeyeLonewolf:
Originally posted by zeuszen:
Originally posted by kirbic:
Originally posted by zeuszen:
Thanks, F. Should I ignore "Lightness" then as well as "a" and "b" while proceeding with curves etc.? |
Try experimenting... Lab is, well, just different. Try sharpening on just the L channel, for instance. Or try running curves on either a or b, or a combination. Personally, I don't use Lab mode that often, but I have sen some folks get some pretty remarkable results with it occasionally. |
Well, yes, I'll experiment, however...
there are no "a" or "b" channels in CS4's Curves. They don't exist. Also No "L" channel, unless you're abbreviating "Lab Color" (Mode)...
? |
Image | Mode -> Lab color
THEN go into curves layer.
There they are... in the dropdown box above the grid. "Lightness" "a" and "b" |
No, they aren't, not in CS4, I swear. -Oops, they are there now! You have powers!
Muchas gracias, muchacho.
Message edited by author 2009-02-28 11:47:50. |
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