Apply Image in LAB Question

GB
Posted By
George_Brown
Mar 18, 2008
Views
351
Replies
5
Status
Closed
I am presently taking the The LAB Frontier course by Dan Margulis at Kelby Training and I am having difficulty with the Apply Image command working the way Dan said it would. I am using CS3 on an PC.

Dan makes extensive use of this command in sharpening and other functions as follows:

Be in LAB color mode.
Start with a Background layer and duplicate.
Oversharpen Layer 1.
Have Layer 1 selected and go to Apply Image.
Apply the lower layer Lightness channel to the top layer reducing opacity to 50%. CHANGE THE MODE TO DARKEN. This is my problem as Darken is not an available choice.

I have tried this on two different PCs with the same unfavorable result. Does anyone have an idea why Darken mode is not available to me?
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GA
George_Austin
Mar 18, 2008
See earlier topic:

"Why no lighten/darken blending modes in Lab?" Francesco Fantauzzi – 09:48am Mar 9, 2008 Pacific

Basically, I think, Lighten and Darken blend modes are not available in LAB because the LAB Lightness channel takes care of luminance.
GB
George_Brown
Mar 18, 2008
Hi George,

I thought that, too. However, Dan Margulis demonstrates this in several of his training videos. He states that lighten/darken is only available if you select the Lightness channel. You can actually see it work in his videos…but it does not work for me.

GB
MR
Mark_Reynolds
Mar 19, 2008
Yes in CS2 you can select ANY if the channels in LAB and using Apply image you can select the blend mode you want including Lighten, Darken. I doubt this has changed in CS3, you are probably doing something wrong. Make sure an active pixel layer is targeted.

If you ask me the whole Margulis approach of converting back and forth to LAB is severely flawed, Luminosity, Saturation, Color and Hue blend modes are available in RGB. Learning to use these successfully will allow you to achieve the results that Dan achieves in a much less destructive way.
GA
George_Austin
Mar 19, 2008
This is interesting to me because I had never explored "Apply Image". Didn’t even know it was there. But playing with it, I was able to invoke ALL of the blend modes in LAB, provided I used the Lightness channel exclusively.

Exclusively means that BOTH target and source are confined to the Lightness channel.

"Target" and "Source" are introduced for flexibility in the Apply Image command. They allow you to blend two layers not necessarily one on top of the other as in the usual blend operation. In Apply Image, the Source acts like the top layer, so it is the layer for which you designate the blend mode.

Here’s what to do: Open two images. Put both in LAB mode. For whichever is the target, go to the channels palette and deactivate the a and b channels, leaving only the L channel active. Then invoke Image>Apply Image. In the dialog box that comes up, choose the other open image as the Source and, if it has layers, designate which one you want to use in the blend . Select the L channel. Now select a blend mode for this source. You will find, SURPRISE, that ALL blend modes are availble to you (no longer are some, like Darken or Lighten, grayed out).

Again, what is new to me is that Apply Image affords a convenient way to blend layers from disparate sources rather than being confined to having them in the same image AND one on top of the other. Works well in RGB also, and there you don’t have to restrict the channel to access all blend modes. In LAB mode, restricting operations to the Lightness channel in order to access some of the blend modes requires a touchy procedure which, if not followed, leaves these modes still frustratingly grayed out.
GB
George_Brown
Mar 19, 2008
George,

For whatever reason, I was able to get it to work this morning.

If you want to continue to play, you can create some very interesting masks. Add a layer mask and be sure it is selected. Then go to apply image. Now you can select merged channels, individual channels, or channels from another opened image (and they will preview). You end up with some really interesting masks.

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