What to try
- Choose an output pixel and change wave amplitude or wavelength.
- Compare nearest and bilinear sampling; set amplitude to zero to restore the source.
What to look for: Inverse mapping asks the fixed source for each output value. The highlighted source coordinate can be fractional and wraps horizontally at the boundary.
How it works
Inverse mapping begins with an output location and asks which input coordinate belongs there. Offset shifts coordinates; waves add periodic displacements; twirl rotates more strongly near a center. Polar mapping exchanges angular/radial and rectangular coordinates. Kaleidoscope folds the image into repeated angular sectors.
The source coordinate is often fractional. Nearest sampling selects one pixel and bilinear sampling combines neighbors. The Lab’s bilinear interpolation uses premultiplied alpha. Boundary modes decide what happens when the requested coordinate lies outside the source.
Use it in the Lab
Use a dedicated distortion on the active layer and compare before committing. Keep document Rotate/Resize for global geometry and use these maps when the deformation itself is the image treatment.
Limits & distinctions
Remapping does not guarantee a seamless or reversible transformation. Folds, cropping and resampling can discard information, so preserve the source layer.
Sources & references
Guide updated