I was going to flip a layer and noticed the Exact Align via 4-Point Path option in the Layer > Transform menu. I checked the Gimp 2.8 manual and it isn't in there. Neither is the Cage Transform tool.
Bottom choice in this menu screen print.


Anyway, I kind of played around with it a bit. It requires a 4-point path and whatever you choose to go on that path.

I used text to check it out.
This is the dialog.


I chose the second option and I can't figure out how that option explains the results.

Screen print of path, original text and the results.


It's interesting and I am assuming there is a logical, useful way to use it.

good chances that is explained as comment to the code.

I have not but i remember RobA (and Ofnuts and Saulgoode ) wrote several scripts to align according to path ,

anyway if is a python script should be in the plugin folder, if script fu in the script folder, and the lines of comments are in plain English

I can't find it in my user scripts or plug-ins folder. I checked it in the plug-in browser and it's named: gap-exact-aligner so I am assuming it's something that is with the gap installation.

that is a good hint but then is a C plugin.
Anyway Gap has not a proper help but is well documented, there is a folder called Doc in the source code and there a quite good manual (except that is all text no screengrab or illustration

...yes i agree the source code of a plugin is not exactly the first place were a user would look for info, but well now you are also using Linux so the Doc folder is in the Gap code . (It would be pure sadism say "the doc folder is in the source code" to a windows user)

and in any case you may copy from the source code also " gap-exact-aligner.c" and open with a txt editor
Don't worry for the "code" just ignore the code and look for the comment lines in plain english

Looks like it aligns to the curl of the plane via right-hand rule. Cool stuff.

It would seem the filter is similar to my Fit Face script, mainly differing in the order of the path points.

Despite the name, my script is not limited to just "face replacement"; it works with any type of layers (I have mainly used it for map overlays). I mainly chose the "face fitting" terminology to make the process more easily remembered -- you draw a line on the face layer, then you draw a line on the target layer, and the script will scale and rotate the face layer to align the two lines. Of course, you aren't really "drawing lines on a layer". You are entering path points (independent of the layers). But by thinking of them as lines associated with features on the two layers, it is less confusing (at least to me).

I'm still playing with this and trying to reason out what it is doing. The two lines through the image were done by centering the image and putting up guidelines at 50% and drawing on them.

I cut through the path rectangle with path lines to see if they would give me a clue as to which way the image was tracking. It looks like the two lines marked with the red X's are somewhat parallel.

I'm also wondering if in the process the image momentarily becomes a vector as the rotation did not seem to affect its quality.

Hey guys!
I used a similar script that's also called Exact Aligner and uses 4-point path http://registry.gimp.org/node/18961
It's a different script (no second option) but I think the same principle is involved.
To make it work properly and predictably the path should remain open and be a zigzag-like.

The layer to be moved should be active.
I can't check it out with Exact Align via 4-Point Path script (could not find it anywhere) but am pretty sure that's how it works.

I saw Exact Aligner the other day at the registry. It looks useful, I downloaded but haven't tried it yet.

Ah, I just assumed the 4 point path should be a rectangle. Your zigzag style makes much more sense.

Interestingly, a hard drive search for it didn't find it on my machine and I do have show hidden files allowed. I think it must be inclusive in the gap installation. Here is a screen shot of the plug-in browser's dialogue about it.

Yes, Oregonian. Wolfgang Hofer is the GAP developer. So this aligner function must be included in one of the GAP C plugins.
No wonder you could not find it.
More news. Found on the GIMP mailing list (this is a part of the thread):

>> GAP ........ seems to be abandoned by its developer for good.

>Alexandre Prokoudine
>But it isn't Most recently Wolfgang added GUI for the exact align
>transformation plugin. He just lacks the time to adjust the code for
>2.8 (actually, I was going to have a go at it, but never found the
>time either) and do a release.

GAP is not abandoned (Yay!!!) and exact align plugin has a new GUI.

Thank you for the info. Hooray for GAP not being abandoned.

I love GAP. It's alive and well in my v2.8.2 of GIMP as far as I know. It's there anyway. I haven't used it in v2.8 yet. Guess I'll have to try it out on something to see if it's working. I'll do my GAP a Ghost tutorial for a quick try at it.

If I have any problems with GAP, NOW I KNOW WHO TO CONSULT.

You're welcome, O!
I'm having problem getting it to work on my Win-64 GIMP 2.8.2. So much for a consultant, lol. But I've tested recent 64-bit PC's Lab built (thank you PC!) and GAP seems to be working properly. I have yet to give it a more thorough try, tho.

What problems ?
I used the 64 bit version of 2.6 from Samj (see http://samjcreations.blogspot.it/ ) but should work well also the 32bit build from JamesH (that i installed in the 32bit but should work also in the 64bit version, if placed in the right subfolder in "32")

The JamesH built is more recent, it is from a 2.7 version ...and when gimp load displays a frightening amount of flashing black console windows..all harmless .

Something that may got broken is " Filter all layers" and "Frame Modify/apply filter ", maybe for the changes of plugin API support for some plugin may be now broken ... not sure is just a doubt

I wonder why the exact-align is part of GAP because it has a lot if uses outside of animations. Fortunately the old exact-align script remains available.

From what I have understood of the upcoming combined transform tool, the exact-aligner will become somewhat less useful since you will be able to replace it by:

1) move the active layer so that one of the points matches its reference
2) start the combined transform
3) set the Scale/Rotate center to the point used above
4) Scale/Rotate to align the second point

Exact align would be indispensable to make a video like this one



Each and every frame is perfectly aligned to person's eyes as the reference points.
I guess GAP would be less complete package without precise aligner.



I'm hoping Unified transform tool will be less buggy that it's already expected to be. Until then, we wait.



Hi, PhotoComix! No, I never said it was an issue with your portable GIMP 2.8.2 PC_Lab GAP. On a contrary, it seems to be working.
I just haven't done anything yet in GAP beside extracting frames and checking a couple of other things. I was talking about GIMP 2.8.2 that I have on my main computer now.
I have GAP migrated from 2.6 version where it worked fine, but with the current version I can't even extract video frames.
Thanks for dropping samj's link. Maybe it's time to refresh some of my broken plugins and scripts.

Yes i did understand that your problem was not with my version, for that i added the link of the version i am used.

I had to replace the link to the GAP download in the Ghost tutorial. Is this the best place to get GAP now?

http://www.gap-system.org/Download/index.html