help with figuring out masking & layers issue please

[pliant slate]

So I was following a tutorial on cutting out the background while keeping a shadow for my product photography.
The issue came when I tried to make the background transparent so I don't have to color-match it with my website's background color.

Pic 1 - solid color background layer is visible
Pic 2 - that layer is hidden

I can't really understand how does PS know it should replace that white color behind the shadow with blue, but keeps it white when I delete the background color instead of making it transparent. Is there a way to work around it? Maybe someone can explain the logic behind how this works?

Steps I did that are relevant to the problem:

1. Roughly masked the shadow
2. Leveled the whites (Pic 3)
3. Added black & white filter

Thanks :)

help with figuring out masking & layers issue please

[peak wedge]

Not really sure what they are trying to tell you in this tutorial to make it work.
But I'll have a guess. The level 1 layer should make it so the whites matches the tone (not the colour, but the luminosity) of the background. It implies that the shadow as it's shown here, masked as a different blending mode than "normal" (Darken maybe?)
I do a lot of those things and I always use the blend if method, as in
Select the object (without the shadow) and mask it
Copy that layer and invert the mask (you are now left with the background and the shadow
Double click on the layer to make the blend if slider appear and remove all the light areas, leaving only the darker parts (the shadow)
Place this shadow layer behind the product layer
It keeps the shadows with a colour (surprise: Shadows have colours, they aren't black and white)

https://fstoppers.com/composite/how-use-blend-if-advanced-blending-photoshop-545636

I know it's not what you've asked for 🙂

But I thought that you would try the other method as well

In your case, what I think this is, is that they try to lighten the background so much without touching the shadow as to make it whiter than the background. Hence the need to change the blending mode to one that eliminates lighter tones, if that make sense...

[pliant slate]

Thank you!
It took quite a while to figure out how to do it, but the end result is exactly what I wanted!
The hardest part was noticing you can split the sliders to get a smooth transition between the blended and unblended areas :)
Thank you so much again, really appreciate it

[daring plover]

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