Adobe photoshop cs2 User Manual

ADOBE PHOTOSHOP CS2 

Keep in mind that resampling can result in poorer image quality. For example, when you resample an image to larger 
pixel dimensions, the image loses some detail and sharpness. Applying the Unsharp Mask filter to a resampled image 
can help refocus the image details. 

You can avoid the need for resampling by scanning or creating the image at a sufficiently high resolution. If you want 
to preview the effects of changing pixel dimensions on-screen or to print proofs at different resolutions, resample a 
duplicate of your file. 

When an image is resampled, an interpolation method is  used  to  assign  color values to any  new pixels that 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. 

In the General Preferences dialog box, you can specify which default interpolation method to use whenever you 
resample images using the Image Size or transformation commands. The Image Size command also lets you specify 
an interpolation method other than the default.