Blending layer in Luminosity mode without the details (only for transfer of the "contrast")?

[Typhoon859]

Hey, this may be a novice question, but similar to the "color", "saturation", and "hue" blending modes, is there a way to just get the "luminance" information of a given layer/image without the actual details of it to apply onto whatever bas layer/image beneath it?

Thanks in advance!

[Stephen Marsh]

Duplicate the layer or file, fill with a neutral such as white, black or any gray level in color blend mode.

[Typhoon859]

I was so ready to have my mind blown just now, but either I'm not doing it right or I don't get it.

I have two images (of the same subject/bacground but differently mastered), one of which I want to get the luminosity data from and trasfer onto the other.  The one I want to get it from I duplicated and filled with grey in color blend mode which turned it black and white... and now what?  Sorry if I somehow didn't follow but if you could further elaborate, I would really appreciate it.

Thanks again.

[Stephen Marsh]

Perhaps I misunderstood.

Yes, the result is without colour, it is only the luminosity. If you change the blend mode to luminosity then it will layer the luminosity. One can usually just change the blend mode to luminosity, but the way that I read your post was that you wanted to separate/extract the luminosity component, not blend it?

[Typhoon859]

Yes, just changing it to the "Luminosity" blend mode still blends (or, actually, fully replaces) the details of the image in the base.  If anything, what it's doing is taking the chroma/color data from the base and transfering up the the image in the "Luminosity" mode/layer above, as if the base were layered on top in "Color" mode (in fact, I just tried that and that's exactly what it's like or effectively does: the result is identical).

Yes, I am in fact looking to separate/extract the luminosity component and then blend that onto an image (which is actually how I thought the "Luminosity" blend mode would be by default).

[Stephen Marsh]

Yes, just changing it to the "Luminosity" blend mode still blends (or, actually, fully replaces) the details of the image in the base.  If anything, what it's doing is taking the chroma/color data from the base and transfering up the the image in the "Luminosity" mode/layer above, as if the base were layered on top in "Color" mode (in fact, I just tried that and that's exactly what it's like or effectively does: the result is identical).

Yes, I am in fact looking to separate/extract the luminosity component and then blend that onto an image (which is actually how I thought the "Luminosity" blend mode would be by default).

By @Typhoon859

OK, so I'm now officially confused! 

99% of the time, you can just layer any content and change to luminosity blend mode, and you will indeed have the luminosity component contributing to the image without the colour.

But if you wish to "extract" the luminosity component, then that is different. Photoshop refers to the single channel gray values of the luminosity component in a few areas, such as the RGB composite curve, or the blend if sliders.

[Typhoon859]

I'm not sure what the "blend if" sliders are but I am familiar with the RGB composite curve.  Would there be any way to accomplish what I am suggesting using that?  I'm not sure.

I'm not looking to extract the luminocity component for its own sake.  What I'm saying is, using the regular "Luminosity" blending mode DOESN'T in fact do that, hence the reason for my question.  The question is with already the presupposition that I'm not missing anything and that this isn't a bug.  By default, setting whatever image/layer to "Luminosity" mode more like blends whatever colors from beneath into it.  It still acts as a "Normal" layer, just without the color information rather than as just a mask with its luminosity values (which I'm not sure is technically possible or not given how things work, but in any case, that is what I am trying to achieve).

Simply using "Luminosity" as a blend mode only works if the two images you have are exactly the same apart from differences in color and contrast.  When you do this with color, you can have differences in terms of sharpness and textures and details (and stuff like that) and it wouldn't matter; those would remain but the color wouldn't (would change to the colors of whatever you overlayed).

[Typhoon859]

I found a way to (kind of) do what I was looking for (shared it in another comment in response to the original post).  If it still wasn't clear, it can perhaps help you understand what it is that I had in mind.

[Typhoon859]

I found a way to somewhat do it.  Not ideal but it sort of does the job (for my current use/application).

• Make a duplicate of the base layer then merge it with the layer you would want in Luminosity mode.
• Copy that image into a new tab/project.
• From the Neural Filters, use "Color Transfer" with this image onto the original base layer and bump the luminosity up to, seemingly, max to match the contrast/luminosity of the original image with the originally intended other image (or otherwise adjust the slider to your liking).

This works because you've essentially made the colors the same through the initial blend.

If anyone has a more direct solution that doesn't inolve Neural Filters, please let me know >.<

Thanks again!