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12/12/2003

Scale command, or Scaling

Note - these commands affect how the image is displayed, but they do not change the original image data.  This means that there is no need for an 'undo' for scaling - use 'Scale / linear' to show the image as first displayed.  This also means that scaling operations do not work sequentially - any scaling operation works again on the original data.

To scale the image data to 8 bits for export to an imaging utility for printing, for example, use 'Image / scale to positive integer'.


Unless a palette is supplied with the image (GIF files always do, and TIFF files with a Colormap tag do also), Lispix scales a copy of the image data to 8 bits (0 - 255) for display.  Lispix uses original image data for most everything else. Images are scaled according to the default-scale-method accessed by Help / Parameters / default scale method. 

The default scaling method is clip-image, an unfortunate name which I've not bothered to change, which simply makes the minimum image pixel value black (RGB=000) and the maximum image pixel value white (RGB = 255 255 255), with a linear ramp in between.  (Actual 'clipping' of pixel values is done with Image / clip to byte (makes a new image with altered pixel values) or, Scale / Trimmed (redisplays image with trimmed intensity values - does not alter pixel values).

Other scaling methods: