| Value | Meaning |
|---|---|
| NEAREST0 | Nearest neighbor sampling; this is the fastest and lowest quality mode. Quality is normally unacceptable when scaling down, but may be OK when scaling up. |
| TILES1 | This is an accurate simulation of the PostScript image operator without any interpolation enabled. Each pixel is rendered as a tiny parallelogram of solid color, the edges of which are implemented with antialiasing. It resembles nearest neighbor for enlargement, and bilinear for reduction. |
| BILINEAR2 | Best quality/speed balance; use this mode by default. Bilinear interpolation. For enlargement, it is equivalent to point-sampling the ideal bilinear-interpolated image. For reduction, it is equivalent to laying down small tiles and integrating over the coverage area. |
| HYPER3 | This is the slowest and highest quality reconstruction function. It is derived from the hyperbolic filters in Wolberg's "Digital Image Warping", and is formally defined as the hyperbolic-filter sampling the ideal hyperbolic-filter interpolated image (the filter is designed to be idempotent for 1:1 pixel mapping). |
This enumeration describes the different interpolation modes that can be used with the scaling functions. @GDK_INTERP_NEAREST is the fastest scaling method, but has horrible quality when scaling down. @GDK_INTERP_BILINEAR is the best choice if you aren't sure what to choose, it has a good speed/quality balance.
<note> Cubic filtering is missing from the list; hyperbolic interpolation is just as fast and results in higher quality. </note>