Trick for reducing pincushion distortion
Snapper
Registered Users Posts: 42 Big grins
I stumbled on this method of fixing pincushion distortion in images using Photoshop CS, which doesn't have the "Lens Correction" filter.
This image, shot with a 90mm (DSLR) lens, exhibits noticeable pincushion distortion at all four edges of the doorway (the original image was over 3700 pixels wide and has been reduced for web display) :
1. I went to "Image>Canvas Size..." and added 3000 pixels to both Width and Height, with "Relative" unchecked. The actual amount to add is based on the size of the image. I settled on 3000 after some trial and error.
2. Now I had my image in the middle of a large canvas. i went to "Filter>Distort>Pinch..." and dialled in a negative amount, again through trial and error, of -4%. This "bloated" the image and straightened the four curved edges.
3. Now I just used the crop tool to remove the blank canvas around the image. After a little more post-processing here's what I ended up with:
The reason I added space to the image with the "Canvas Size..." command is that the "Pinch" filter acts more on the centre of the image than the edges, so we need to make our image the centre of a larger image.
It may not be as accurate as dedicated lens aberration fixing tools, but as a quick fix it does a pretty good job of reducing what is a distracting distortion.
Hope this is of assistanace to someone!
This image, shot with a 90mm (DSLR) lens, exhibits noticeable pincushion distortion at all four edges of the doorway (the original image was over 3700 pixels wide and has been reduced for web display) :
1. I went to "Image>Canvas Size..." and added 3000 pixels to both Width and Height, with "Relative" unchecked. The actual amount to add is based on the size of the image. I settled on 3000 after some trial and error.
2. Now I had my image in the middle of a large canvas. i went to "Filter>Distort>Pinch..." and dialled in a negative amount, again through trial and error, of -4%. This "bloated" the image and straightened the four curved edges.
3. Now I just used the crop tool to remove the blank canvas around the image. After a little more post-processing here's what I ended up with:
The reason I added space to the image with the "Canvas Size..." command is that the "Pinch" filter acts more on the centre of the image than the edges, so we need to make our image the centre of a larger image.
It may not be as accurate as dedicated lens aberration fixing tools, but as a quick fix it does a pretty good job of reducing what is a distracting distortion.
Hope this is of assistanace to someone!
Ian
Website: igMusic
Website: igMusic
0
Comments
Don't have too many problems w/ this. But this will definately go in the archives for when it does happen (which I'm sure it will).
All the best,
-Jon