Apply cubic bezier curve to image

[shirkavand]

Hi,

Is possible to apply a quadratic(or cubic)bezier curve to an image, so the resulting image will be modified to have a curve transformation in it? Something similar to barrel transformation, so for example i can give a (x,y) and imageMagick based on that ending pont creates and modifies the image with a bezier curve... i' ven using PHP's Imagick shared library, and i've been playing with functions like "pathCurveToQuadraticBezierSmoothAbsolute", "bezier" etc with no luck.

Any idea will be very appreciated,

Warm Regards

[snibgo]

Can you be more specific about what you are trying to do? Ideally with before/after images.

For example: an image could be distorted so that every horizontal line in the original followed a given bezier curve in the output. I would do this with a displacement map. See http://www.imagemagick.org/Usage/mappin ... ement_maps

[shirkavand]

Thank you for your fast reply. Please hek these links:

http://s3.postimage.org/qrzp73osv/Original.png
http://s3.postimage.org/tjiyxpnbj/Curved_down.png
http://s3.postimage.org/njv7u22j3/Curved_up.png

As you can see is something similar to a barrel transformation, but the left and right side of the image are not curved only the top and bottom sides.

Any ideas?

[snibgo]

A similar effect can be achieved with a simple Shepards distortion. Windows script:

Code: Select all

convert original.png -distort Shepards ^" ^
  0,0 0,0 ^
  179,0 179,0 ^
  0,155 0,135 ^
  179,155 179,135 ^
  72,0 72,20 ^
  72,155 72,155 ^" ^
  orig_down.png

[shirkavand]

i already used Shepards before, but it does worked for me. I have just tested your script(using linux) and it does not work either(maybe i am doing something wrong...)

convert original.jpg -distort Shepards \ '0,0 0,0 179,0 179,0 0,155 0,135 179,155 179,135 72,0 72,20 72,155 72,155' down.jpg

Which result in this image:

http://s3.postimage.org/y0e34mv6b/down.jpg

and not something like:

http://s3.postimage.org/tjiyxpnbj/Curved_down.png

[snibgo]

What version IM are you using? I get a better result than you in 6.7.9. More recent versions, eg 6.8.2, allow me to tweak the power factor of the shepards distortion:

Code: Select all

"%IMG682%convert" original.png ^
  -define shepards:power=4 ^
  -distort Shepards ^" ^
  0,0 0,0 ^
  179,0 179,0 ^
  0,155 0,135 ^
  179,155 179,135 ^
  72,0 72,20 ^
  72,155 72,155 ^" ^
  orig_down.png

However, shepards isn't identical to bezier. I think the only way to get an exact bezier distortion is by constructing a displacement map.

[shirkavand]

I'm using: Version: ImageMagick 6.7.9-0, and sadly "-define shepards:power=4" did not make any difference. Are you sure that using a " displacement map" is not a too difficult solution for this problem?

[fmw42]

If on LInux or Mac or Windows w/Cygwin, see my script, curves at the link below. Is that what you are trying to do?

[snibgo]

As I said, shepards:power is only for more recent IM versions.

Displacement maps aren't too difficult. See the page I cited. As an example:

Code: Select all

"%IMG%convert" ^
  -size 180x156 xc:White -fill Black -stroke Black ^
  -draw "path 'M 0,78 C 30,88 60,88 90,88 S 150,88 179,78 L 179,0 0,0 0,78'" ^
  -resize "180x1^!" ^
  -resize "180x156^!" ^
  omap.png

"%IMG%composite" ^
  omap.png ^
  original.png ^
  -displace 0x100 ^
  orig_down2.png

This gives roughly the result you want. The coordinates need tweaking, and the canvas needs expanding so parts of the image aren't lost.

[shirkavand]

This script is exactly what i need:

http://www.fmwconcepts.com/imagemagick/cylinderize/

I need to create a cilinder effect in the images. But i an not use your script because i need to use imagick shared library... so maybe i will need to tweak the example here:

http://www.imagemagick.org/Usage/mappin ... ement_maps under Cylindrical Displacement

[fmw42]

I need to create a cilinder effect in the images. But i an not use your script because i need to use imagick shared library... so maybe i will need to tweak the example here:

Why? You can just call the script from PHP exec(). Note that Imagick has not kept up with many of the Imagemagick improvements.