I must be missing something here ...

[MikeFromMesa]

Sorry for the length of this post, but I need to explain what I am seeing to ask why.

I downloaded samples of some of the books posters recommended and am glad that I did that because reading about stuff that I thought I knew about gave me some information I did not know, at least about what options are available when using Photoshop. I learned perhaps 6 or 7 new thngs just reading the samples of the books. But one of those things that I learned has me puzzled. Not about what is happening, but about why it is happening and something similar is not.

One of the exercises involved loading a single image and adding a new empty layer to it. I know that if the empty layer is slected I can not use most filters and adjustments because there is there is nothing in the layer, but the example told me to check the Sample All Layers checkbox at the top of the image. That was something new for me as I had never noticed it before. It then had me use the Spot Healing Brush to show me that even with a new layer selected I could use some Tools to modify an image. That was also something new for me. In fact I was so surprised that I decided to try some other tools, using the same configuration.

I tried ACR, but it did not work. I tried both the focus and blur tools and they did not work. None of that surprised me too much because the new layer was empty and it seemed as though I could use the Spot Healing Brush because did not change the image layer but allowed me to paint on the new layer (which is what it did. Hiding the image layer showed me the Spot Healing Brush changes on the new layer). What surprised me, and what I don't understand is why the Spot Healing Brush worked but the Healing Tool did not. They both seem to do the same sort of thing - sample the base imae and paint a change - but since they are so similar why does the Spot Healing Brush work and the Healing Tool not work? If the Spot Healing Brush and the Clone Tool both work on the new layer, why not the Healing Tool? 

The reason this bothers me enough to post the question is that I feel that I am missing some basic concept about what is happening, and that not knowing may also mean I don't understand other similar things.

[Signfeld]

It does work with the Healing Brush Tool as well.

Indeed, some tools you would hope would work this way do not (yet). I think the Patch Tool can't, or just in part, or once couldn't. I'm gonna check again.  [upd.: Indeed, works in Content-Aware mode only.]

Clone Tool works too.

It's probably the Current & Below type of settings and icons that are essential when you want to do it in a separate layer.

[Signfeld]

Re. "I tried both the focus and blur tools and they did not work."

If you mean the Sharpen Tool, that does work too, and the Blur Tool.

Check if you have this button active (or if a Current & Below setting is selected).

[MikeFromMesa]

> It does work with the Healing Brush Tool as well.

I tried several times, and it never worked for me, so I assume there is some setting I am missing. I will try again.

> Clone Tool works too.

Yes. This I knew, and commented on in my post. It was the Healing Tool that I could not get to work.

> If you mean the Sharpen Tool, that does work too, and the Blur Tool.

I tried both, and neither worked for me, so perhaps I need to check the settings more carefully.

I have two takeaways from this. The first is that perhaps I am not checking the settings carefully enough if these tools that don't work for me do work for others, and the second is that the feature set in Photoshop is a lot richer and more varied than I originally thought. The fact that I learned half a dozen (or more) new things just reading the sample section of the Kindle book tells me that there is much more for me to learn about how Photoshop works and what it can do.

Thank you all for your help. I will post further on this subject if I still can not get those tools that do work for others to work for me since I will want to try to find out what I am doing wrong. The idea of using empty layers when doing adjustments makes a lot more sense to me if they can be used this way. 

[Signfeld]

IMO, the post before yours explains the main thing. For it to work, you have to tell it to see 

other layers beside the empty one or the empty space in it.

The difference between on/off for this button is not super clear however. The active state is when its background becomes black. (For some tools, you have to use the dropdown)

[Signfeld]

This is my default setting for the Healing Brush to work on an empty layer...

The empty layer ...

[Signfeld]

Plugins in the Filter menu usually work on the current layer, so it usually has to have content for it to work on.

Some plugins just take the merged result of all your layers and give you a new one.

For some it can be predicted with common sense, for others you tend to forget what it's going to do, and in some you can set a preference. To not lose time with that, I call many of them by action and already provide my own merged layer (or not) for it to work on.

[MikeFromMesa]

> To not lose time with that, I call many of them by action

Yes. I can see how that would help. As it is I did some more testing and found that that the Healing Tool does, indeed work on an empy layer if the appropriate checkbox is set, something I did not do before.

And, while the sharpness and blur tools do work on an empty layer, the sharpness and blur filters do not, which was what I meant in my earlier post. I re-read that post and clearly referred to the sharpness (which I called focus) and blur tools, which was wrong. I meant the sharpness and blur filters. I clearly need to be more careful when writing my posts.

Again, thank you for the help. This thread has cleared up my misunderstandings and told me that I am (probably) not missing some basic concept, although I clearly still have a lot to learn about Photoshop.

[Signfeld]

Aha, yes I see 🙂

As most of the filters work on the current layer (and usually need pixels), it gives you the power where you want it applied to.

If you want it applied to the current layer, just call the Filter.

If you want it applied to your merged view of all layers, first make a new merged layer (Ctrl+Alt+Shift+E on PC) and apply the Filter to that new layer. (Again, a few plugins create a new layer themselves.)