7.1.9 Portable Image Files
— Function: pnm:type-dimensions path
The string path must name a portable bitmap graphics file.
pnm:type-dimensions returns a list of 4 items:
- A symbol describing the type of the file named by path.
- The image width in pixels.
- The image height in pixels.
- The maximum value of pixels assume in the file.
The current set of file-type symbols is:
- Black-and-White image; pixel values are 0 or 1.
- Gray (monochrome) image; pixel values are from 0 to maxval
specified in file header.
- RGB (full color) image; red, green, and blue interleaved pixel values
are from 0 to maxval
— Function: pnm:image-file->array path array
Reads the portable bitmap graphics file named by path into
array. array must be the correct size and type for
path. array is returned.
— Function: pnm:image-file->array path
pnm:image-file->array creates and returns an array with the
portable bitmap graphics file named by path read into it.
— Function: pnm:array-write type array maxval path comment ...
Writes the contents of array to a type image file named path. The file
will have pixel values between 0 and maxval, which must be compatible
with type. For ‘pbm’ files, maxval must be ‘1’.
comments are included in the file header.