HELP FLOAT_BYTE                             David Young
                                            June 1992

LIB *FLOAT_BYTE provides a procedure to convert between packed arrays of
bytes and packed arrays of single precision floats.

    float_byte(IMAGEIN, IMAGEOUT, REGION, P0, P255) -> IMAGEOUT;

IMAGEIN must be an array of bytes or an array of single precision floats
(e.g. created using *NEWBYTEARRAY or *NEWSFLOATARRAY respectively).
IMAGEOUT may be input as <false>, in which case a new array will be
created, or it can be an array to receive the data. If IMAGEOUT is an
array, it must be the appropiate type: bytes if IMAGEIN is floats, and
vice versa. REGION may be <false>, in which case the whole of the input
image is processed, or it may be a list specifying a region to be
processed in boundslist-type format. If REGION is specified and IMAGOUT
is <false>, then the array returned will have a boundlist equal to
REGION.

Values are scaled linearly. P0 and P255 must be numbers giving the
values in the float array corresponding to 0 and 255 respectively in the
byte array. The equations are:

    Byte_array_value = (Float_array_value - P0) * 255 / (P255 - P0)
    Float_array_value = Byte_array_value * (P255-P0) / 255 + P0

Thus if P0 is 0 and P255 is 255, the values are left unchanged as far as
possible. When storing data in a byte array, values are always rounded
to the nearest integer; any value greater than 255 is stored as 255 and
any value less than 0 is stored as 0.

--- $popvision/help/float_byte
--- Copyright University of Sussex 1992. All rights reserved. ----------