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In this tutorial we deal with correct perspective a photo with Gimp. Often (especially in the narrow streets) having to take pictures of monuments or facades of tall buildings, having available a limited field for framing. It is clear that we will be closer to the monument over the photo will be “far” from being correct axonometric. The perspective correction is also called correction (or modification) the falling lines. This is because taking a photo close to an architectural element gets the impression that the monument is falling backward (the architectural lines converge upwards.

What we will do today is “straighten” the lines of a facade, Gimp well as we should have another couple of plugins: “MathMap” and “FX-Foundry“.

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MathMap is a plugin for Gimp rather complex. Can also be used as a stand-alone command-line, but of course it is easier to use with Gimp because of the graphics facilities that follow. Unlike MathMap FX-Foundry is a plugin much more primitive. Creates an entry in the main menu and special deals only speed up some operations already feasible with Gimp, but that would cause us to lose time.

We find the filters MathMap below “Filters” – “Generic” – “MathMap“, and filters FX-Foundry in its menu (on call to bar menus).

First we take a picture that lends the work. Transform the first photo, and the final result is the following:

  YoHDR: a site to create HDR photos
Finished work
Finished work

The first thing we must do is correct perspective. Let's go over “Filters” – “Generic” – “MathMap” – “Distorts” – “Bilinear interpolation“.

Let's go under the tab “User Values” and move the value “a3” trying to verticalize as much as possible the lines.

Now we'll have to cut off le zone “Empty” image with the instrument “Cutter”  .

And now we will give a cut to the next step by adding the authentic vignetting. “FX-Foundry” – “Photo” – “Effects” – “LOMO Effect“.

At this point in the tab “Levelsreduce the opacity vignetting of the 50%, so we get the final result.

Lavoro ultimato

This tutorial is for the sole purpose of show how to correct the perspective of a photo, we must not forget, however, that photography is art. If a picture we like it like no one forces us to correct colors, the’exposure o la outlook. It all depends on the outcome we want to achieve.


I keep this blog as a hobby by 2009. I am passionate about graphic, technology, software Open Source. Among my articles will be easy to find music, and some personal thoughts, but I prefer the direct line of the blog mainly to technology. For more information contact me.


John · 5 June 2014 at 12:00 PM

Oh, are ricapitato on your blog! 😀

Only the GIMP menu has changed since that time :/

    Giovanni Mauri · 5 June 2014 at 7:05 PM

    Ummhh.. not stop mi… “filters” – “generic” still exists. Mathmap is a plugin to be installed separately. You can find it in the Ubuntu repositories.

voucher · 14 June 2010 at 3:39 PM

for example, I preferred the original own this photo! 😀
but…are views! hihihi ..ciaoooo

voucher · 14 June 2010 at 3:38 PM

I must say that the effect “LOMO” I like! 😀

However, like you said “photography is art” and is an important thing, because sometimes the best photos are those that are not really correct…but I must say that the bits of advice that you gave to the post-production are very interesting. Really Bravo! 😉 mi piaciiii

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