Image scaling as described here applies to viewing and conversion.
The image viewer always uses the Averaging method.
Three different scaling methods are available for conversion.
You select scaling method in the Image Size dialog.
- Pixel Replication
- This is a fast method. However, it may lead to blocky images for large scaling factors (example 1).
-
- Interpolation
- This method employs bilinear interpolation between four neighboring pixels. This method is slower than pixel replication. It reduces the blocking by making more smooth transitions at the expense of sharpness (example 2).
-
- Averaging
- This is an alternate interpolation method. It performs anti-aliasing without reducing the sharpness significantly. It is recommended for downscaling and for scaling of images containing patterns, for example, images scanned from a printed source (example 2). Also images with thin lines (example 3) should be scaled using this method. For large scaling factors it induces the same blocking artifacts as pixel replication (example 1).
-
