The above is what I’m looking for. From what I’m seeing, it’s like a direct sphere projection applied to a image. But the thing is no matter the scale, it follows the line of a half circle with that scale. There’s nothing in the sort in GIMP, or in G’MIC, or Krita liquify transform, and so on.
Edit: I found the closest I can get are within Krita deform brush. It’s really close to the effect I want, but it’s not exactly without problems.
Just a little update: On the Paint.NET forum, I have created a thread, and I found that there are source codes on the FishEye effects (Forward, and Reverse). Is it possible to implement those on G’MIC?
Edit 2:
I found something else here - Pinch and Spherize Filter - File Exchange - MATLAB Central
Maybe check G’MIC>Deformations>FIsh Eye; could be what you were looking for. 
That is what I have tried, but the result isn’t exactly the replica of Photoshop spherize effect. In the Photoshop spherize effect, the boundary are always somewhat cutoff, even at small value. You also have the reverse direction in Photoshop spherize. Spherize doesn’t exactly behave like the FishEye filter.
Here’s a example of the reverse direction.
Well; tried various Mathmap distortion presets too but alas, did no see any that can mimick this. The only thing you can do is use iWarp with a large radius, but it’s not as precise as you would want it to be but it can replicate this.
An example.
Going the other way with iWarp. 
Iwarp seem to have rectangular warp rather than spherical warp.
Here’s my trial. Maybe not exactly what you want, but still a cool filter to play with
(and was fun to do).
Filter available after an update, in Deformations / Spherize.
Source code of the new -spherize command :
Hope it will be useful (if you think so, please click here 
)
UPDATE: Added controls for ratio and angle of the elliptical shape.
I really wish I can donate, but I am just a student for now. Really awesome spherize effect. It’s better than Photoshop spherize for most applications. There’s something I’d like to point out.
I do wish that I don’t have to use the smooth to adjust the perceived tangency angle line on the edge of the circle. Hmm, if one is somehow able to alter the curves near the edge of the circle after smoothing, then this would be even better than Photoshop spherize effect for some task. Pinching the circle edge from the inside would be the answer to this problem or adjusting tangency angle would also be another answer. The second one would be better with some smoothing to fix the issue with altering tangency alone. But, that’s just a minor complaint, other than that, perfect.
I am looking at Euclidean to Polar, and I am finding that in theory, you might be able to fix that issue when smoothing is already applied by altering where the the edge is and then transforming it back to Euclidean.
Now that just way too awesome, David. lolol
G’MIC’s the bomb. Nothing close in PS world. Thanks for your continued enhancements with the best retouching tool out there (and your team too of course), David.
Hi all,
I have a very faint memory of a built-in filter in The Gimp at the end of the 1990s that had similar properties… It was located close to the Bump Map, but I cannot recall the name of it 
Anyone else remembers it? It could wrap an image around an object, like a sphere, a cylinder, or a cube.
Have fun!
Claes in Lund, Sweden
I wonder if you could also add the converse options as well, David (as shown in the landscape sample)?
Probably a bit harder to invert, as the math formula I’ve used does not seem particularly easy to invert.
But I’ll probably take a look some day (not the next week BTW, as I’ll be really busy).
That’s cool, David; do know how busy things can get.
You’re looking for Map Object. That is one of those things I would rather use a 3D program.
Yes, that’s the one! Thank you!
Claes in Lund, Sweden
