Having original photo and modified one (applied styles on whole photo, not regions), is there a tools that can reverse-engineer made changes? The output would be the list of changes that can be applied on original photo, so it become close to the target one? It does not have to be super-precise; it's more for learning purpose.
Reverse engineering contains word
engineer for a reason.
Those tools are non-existent for a number of reasons:
- even small number of modifications may be applied in an astonishing amount of orders -
6!=120orders of applying only 6 adjustments even if the modification software is known. Even Paint.NET has a magnitude more adjustments than that
- there is no standard for image modifications. Even more than that: most of popular software is propriatrary (the specifics of algorythms corresponding to adjustments are unknown) and EXIF containing the name of program is oftenly stripped
- you said that the initial image is available but it is available in vanishingly small number of cases and in these cases you may ask the author about processing technique as well
- modifications may be local
- the colour space in which modifications were done is unknown
In rare cases the information about applied adjustments is stored in EXIF data either by camera or by manipulation software.
There are miriads of processing tehniques created and vast amount of them were created by hobbyists. All you need to create one yourself is reading the manuals for the software which you use and experiment - it is that easy.
In my opinion there is a total contradiction between this two sentences:
Used presets and styles?
It's more for learning purpose.
1) A preset and a style can be called "Arizona" or "Pinky dinky" You can probably asume that "Arizona" could have a brownish look and "Pinky dinky" a pink tone. But it says nothing more. It can be a total arbitrary set of adjustments.
2) In general terms a Preset is going to lead you to learn almost nothing... just press a preset. That is what a preset is for, so you do not bother on thinking about the process, just do you like it or not.
So if the best way to learn is to analyze.
Some of the basic points to analize are:
Contrast. Is it more contrasted or less?
Black point and white point. The current "vintage" trend has a tendency to asign the darkest poing of a photo not on black, but on gray.
Saturation. Is it colorfull or "grayish"
A more "advanced" part is
Contrast on light parts or dark ones. Do we have blown out light and detail on shadows or viceversa?
General color. Has the image an overall coloration? Is that because the original light (color temperature) or is it because a post process? The "leaked light" effect, as the one produced by a leak of light on a film container cas gradients of colors on it.
Micro contrast... the so called "HDRI look", which in real terms is tone mapping.
The way to learn is
1) Having a methodology.
2) Having some basic set of individual elements to work with.
3) Doing it yourself.
There are some programs where, when you apply an effect, it gives you the "history", or put the diferent steps as "layers" a set of instructions where you can adjust them. And you will see that the basic blocks are almost the same everywhere.