This script simulates the Lomo effect. Copy it into the scripts folder from GIMP, you will find it then under Filters -> Light and Shadow -> Lomo.
The original from Francois Le Lay can be downloaded here. The idea of C41 colors comes from here. I added sharpness, repaired the double vignetting problem and added some nice colors, especially the beautiful green sky effect from Lomo pictures. Examples can be found here.
Attention, results may make happy.
Update: I refreshed the colors and added another vignette, but this is black and can be moved and resized. The result should be made grainy with my other script, then it looks more realistic.
Update2: The overlayed vignettes are moving now with the black vignette. That means all vignettes have the same center.
Update3: I added a slight lens distortion to simulate the wide angle lens of the Lomo LC-A. And if you own the grain script already, you can uncomment line 285 of this script to get a grainy black vignette automatically. Example here.
Update4: New color "Autumn" to simulate this. To include vignette graininess, uncomment line 314. Result here and very impressive here.
Update5: I mixed the angle distortion up, now it bends to the right direction. And the source code became prettier thanks to Dr. Scheme.
Update6: I added optional motion blur to simulate 'bad' lenses, see here.
Update7: Two new colors Movie and Vintage. Also more decent sharpness with layer mask. And I included the grain for the black vignette, so you don't have to do this. Examples here and here.
Update8: New color Xpro LAB from this book. Example here.
Update9: Possibility to inverse the A and B dimensions of the LAB color space. Example here.
Update10: Fixed the b/w problem. Added a new color option Light Blue from this role model. Example here.
I also attached the colors I use. Extract and put them into the curves folder of GIMP.
Update11: Lens distortion is adjustable now, the default is less extreme.
Update12: New color Redscale from here. Example here. The Light Blue color now has a less violet tinge.
Update13: Extensive internal fixes (eg. motion blur fixed). New option grain and gauss blur. Also sharpness is done via smart sharpen from eg and not overlay.
Update14: Sharpness layer is better on top.
Update15: Sharpness one down, grain deactivated while sharpening.
Update16: Redscale is now closer to the physical approach. Example:
Update17: Movie color option reworked, three new B/W tones: Retro, Paynes and Sepia.
Update18: Added batch version, run it with
gimp -i -b '(elsamuko-lomo-batch "picture.jpg" 1.5 10 10 0.8 5 1 3 128 0 FALSE FALSE TRUE FALSE 0 0 115)' -b '(gimp-quit 0)'
or for more than one picture
gimp -i -b '(elsamuko-lomo-batch "*.jpg" 1.5 10 10 0.8 5 1 3 128 0 FALSE FALSE TRUE FALSE 0 0 115)' -b '(gimp-quit 0)'
Be careful, the batch script overwrites the original image. More info here:
Update19: Reduced vignette banding with the spread tool.
For all scripts together, go here.