The shortcut may be helpful for some people. Thanks!

RGB
   ↓ ↓
CMY
   ↓ ↓
LAB

Follow the arrows to get the channel A, the top Green, bottom Magenta.
The channel B, the top Blue, Yellow bottom.

Hopefully this will be helpful.

Thanks for the update. These results are as expected, but it is good to have confirmation.

As I had promised I did a test with reduction of saturation, reduction of contrast and selective sharpening.

Desaturation – works well. With it I can do MMM and CB after it. And the result usually better than it was at the original photo.
Decontrast – doesn’t work at every single picture (I tried several options for decontrast – ACR Filter (RGB), Curves in LAB, Curves layer in LAB). The result is almost the same after the all corrections. That can work in a case when you have difficult picture where you have to do a lot apply image operations. There is a sample picture in the book with the canyon.
Selective sharpening – works well if it is combined with image reduction with Bicubic (Smooth gradients) algo.

That is all

PS. If it is more or less clear with color and sharpness but I need to check my ideas with contrast. To date I don’t understand worth it to reduce it before increasing or not If yes then when….

The PPW Sharpen action is very complicated and also very flexible, so it’s worth reading the documentation carefully. One of the reasons for its development was that I was confronted with cleaning up the mess when others had already sharpened the image, usually badly. So it can indeed be configured to un-sharpen parts of an image.

I am no expert on how individual smartphones sharpen their output but I’d be surprised if it was anything more than a simple low-radius, dark and light halos treated equally, kind of thing. So you could turn the two corresponding layers off entirely in the PPW sharpen action and still get benefit from the other three.

Also, I agree with Mathias that custom-sharpening local areas of an image is time-consuming and generally to be avoided, but that sometimes the image is valuable enough that we wish to do it. This is why the layers are in the form of editable halo maps. Rather than work with layer masks, I prefer to edit the maps directly. It has no advantage if you are just trying to reduce or eliminate the sharpening in certain areas. But if you don’t really wish to eliminate the sharpen totally, but only the apparent grain that it produces, you can curve the halo map to eliminate its lightest areas. Also, in the event you want *more* sharpening in a certain area, lassoing the appropriate part of the map and increasing its contrast will do that.

Your comments on numbers are quite correct. Also, I am happy you had this success with the volcanic shot. It is always difficult when weather conditions interfere with a lovely composition. LAB is often the solution.

I agree with the angles you chose, this is what I commonly use when working in this way.

It is similar to being the inverse of Color Boost, but if you are using the CB defaults, it is not *exactly* the inverse because the (user-changeable) default is to emphasize the A channel more than the B.

Of course, you would never desaturate the image if you wanted only to apply CB, that would be like traveling from Moscow to St. Petersburg via Vladivostok. You desaturate because you wish to use MMM in some form.

Dan helped with downgrading of the colors. If we do reduction of saturation then we can apply MMM and receive more color variations. And that is amazing.

But should we try to do something else to reduce smartphone effect? Unfortunately we can’t make these things inside smarphones because their camera applications are very simple and don’t allow to change photos towards reduction of “picture postcard” effects.

Now I’m thinking about not only color reduction before MMM and CB but also about contrast reduction before increasing of contrast at stage 2 (increasing contrast per channel). The same way as we do it for RAW files (it is described at the book). I think that this will be easy.

But I have one more concern. That is about “sharpeness” of smartphone photos. It is not easy to apply PPW Sharpening set of actions to already shaprened picture. The result looks disgusting. I’m trying to reduce this problem with decreasing size of the picture with “Smooth gradients” option. That eleminates 50% of the problem. After that I switch off some sharpening layers or increase their transparency. That helps for another 25%. But I don’t know what to do with the rest 25%.

So I’ll be thankfull for any other suggestions or approved practises.