Choosing an interpolation method

When an image is resampled, an interpolation method is used to assign color values to any new pixels Photoshop creates, based on the color values of existing pixels in the image. Photoshop and ImageReady use sophisticated methods to preserve the quality and detail from the original image when you resample.
The General Preferences dialog box lets you specify a default interpolation method to use whenever images are resampled with the Image Size or transformation commands. The Image Size command also lets you specify an interpolation method other than the default.

To specify the default interpolation method:

1. Do one of the following:
• In Windows, choose Edit > Preferences > General.
• (Photoshop) In Mac OS choose Photoshop > Preferences > General.
• (ImageReady) In Mac OS, choose ImageReady > Preferences > General.
2. For Interpolation, choose one of the following options:
• Nearest Neighbor for the fast but less precise method. This method is recommended for use with illustrations containing non-anti-aliased edges, to preserve hard edges and produce a smaller file. However, this method can result in jagged effects, which become apparent when distorting or scaling an image or performing multiple manipulations on a selection.
• Bilinear for a medium-quality method.
• Bicubic for the slow but more precise method, resulting in the smoothest tonal gradations.
• Bicubic Smoother when you're enlarging images.
• Bicubic Sharper for reducing the size of an image. This method maintains the detail in a resampled image. It may, however, over-sharpen some areas of an image. In this case, try using Bicubic.