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Old Nov 24, 2008, 2:10 PM   #1
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Hi; I want to experiment with the Color Lab mode in CS3 (Windows XP); problem is as soon as I select "Color lab", image goes black. I changed blending mode from "multiply" to "overlay", but this won't help. Any ideas or suggestions on why is this happening? Thanks!
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Old Nov 24, 2008, 6:18 PM   #2
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At what time are you converting to Lab Color Mode? There should be no change in your image when converting to different mode. A slight variation might be seen but the printout is where you will see the difference. For better color control Always switch RGB to CMYK and then adjust the curves. You now have precise control over C, M, Y and K. Remember to switch the mode back to RGB so you can print it. Let me know about the Lab Color question.
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Old Nov 24, 2008, 8:07 PM   #3
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Hello, Bynx...I just wanted to try the "Color lab Sharpen", I need to open a picture before switching to Color lab mode, but this is to no avail...it always shows a black square.
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Old Nov 24, 2008, 11:03 PM   #4
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artmustel, I won't swear to this, but I have the impression that you can't convert to or from LAB color mode without first flattening any layers that you have open. Once in LAB color, you can go crazy with your layers.

You can get a similar result to LAB sharpening in RGB color by going to Edit>Fade Unsharp Mask on the very next step after applying Unsharp Mask. You'll get a box where you can adjust the opacity and blend mode. Choose Luminosity for the blend mode and the Unsharp Mask effect will be applied only to the luminosity data. This is what the LAB sharpening procedure is supposed to do. Technically, I don't know if the result is exactly the same, but the idea is the same.

You can do color enhancements in LAB mode also that can't be duplicated in RGB, and by applying Gaussian Blur to the A or B channel (or the A and B channels) you can reduce chromatic noise. Unfortunately, if you get aggressive with the blurring, it cuts down on the images color saturation. But sometimes that's better than a really noisy image.

There's a great book out by Dan Margulis on the subject of LAB color and the things that can be done with it:

http://www.amazon.com/Photoshop-LAB-.../dp/0321356780

Even used it ain't cheap, but it's a very useful book!

Grant
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Old Nov 25, 2008, 2:07 AM   #5
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Grant is right. You choose Lab Color immediately after opening your picture file. Once in Lab color then you can use the channels available to you. Im getting an ebook copy of Margulis' book. As well I have Linda.com Photoshop CS3 Mastering Lab Color. Email me tomorrow afternoon.

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Old Nov 25, 2008, 1:49 PM   #6
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I am not creating any layers before going into Lab Color Mode...I just open a picture, any picture, then change to Lab Color, and the picture goes totally black. Even if once in Color lab I open channels, I see the first channel like a black square, then the other 3 channels in black and white, like they are supposed to be seen.
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Old Nov 25, 2008, 2:04 PM   #7
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Sounds kind of weird to me. Can you get on IM now? This is from someone with the same problem. http://www.flickr.com/groups/7points...57605146901768

The best answer is to reset your CS3 Preferences and then download updates for ACR and LR to get the lab color working properly. This procedure worked for one guy. But another one says the issue was related to different processors reading SSE instructions differently...or something like that. Having an AMD on the desktop and an Intel on the laptop. So maybe the problem will finally be solved.
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Old Nov 25, 2008, 4:04 PM   #8
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Hm, I don't use Photoshop... but still it sounds strange to me. In PL32 (my gfx program of choice) I have two ways to do this:

- I choose a bitmap layer, i.e. the background layer ofa JPEG file, then use Tools->convert layer->Lab (8bit or 16bit). This changes the complete layer to Lab

- I also have a checkbox at that control to apply these changes to the whole document (all layers)

Additionally, when I just want to use a special function like "sharpen", USM, whatever, in a different color space, I've got a dropdown control in the tools window to change working color space just for this operation.

However - to get the hang of sharpening in different color spaces, I'd suggest to extract the specific channel to a seperate greyscale image and examine it and postprocess it on it's own. If ready - exchange that channel with the current picture. If I need this (channel selective noise reduction, detail works etc.) I mostly duplicate the image background and do the channel stuff on the topmost layer. When I am done I can fine-adjust the result via opacity. Maybe a tad complicated, but I haven't found a simpler way in my program to do this yet, am still learning things even after using it for years now .

As for Lab sharpen in general, it's no one-hit-wonder and sometimes working in HIS and using only I channel is better with the same given sharpening method... and then there is CMYK, too. Start slow and work your way towards an easy an reproducable approach.

Good luck,
Th.
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Old Nov 25, 2008, 4:59 PM   #9
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Thanks, Bynx, but those sugs didn't work for me. Maybe it is a processor related problem or else...
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Old Nov 27, 2008, 5:47 AM   #10
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artmustel..............did you dig further from the link that Bynx gave you ?
There was another link where I found that some were having a problem with the camera raw update at that time (to 4.4.1) and it worked, for me too, by reverting to the previous version (4.3.1).
Though if you regularly update camera raw, then the suggestion may not help you.
If you don't (update regularly) then try doing so to the latest (and last) update for CS3 : http://www.adobe.com/support/downloa...jsp?ftpID=4040

And if you haven't already, update the program to 10.0.1 : http://www.adobe.com/support/downloa...jsp?ftpID=3775


I use an AMD processor and haven't had a problem since reverting (at the time), or updating after version 4.4.1
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