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Man Pages


Manual Reference Pages  -  FLOAT_TO_EXP (3)

NAME

float_to_exp - Convert floating point values into "exponential" pixels.

CONTENTS

Synopsis
Description
See Also
Author

SYNOPSIS

#include <rle.h>

float_to_exp( count, floats, pixels )

  int count;
float * floats;
rle_pixel * pixels;

DESCRIPTION

The function float_to_exp converts count floating point numbers (pointed to by floats) into count+1 bytes (pointed to by pixels) using an "exponential" format. This format generates count pixels as eight bit "mantissa" values, and another byte containing a common exponent for all of the data values. This format has a wider dynamic range of values with little extra overhead. The inverse mapping is
        float expnt, flt_val;
        rle_pixel exponent, val;
        expnt = ldexp( 1/256.0, (int)exponent - 127 );
        flt_val = (float)val * expnt;

Files containing exponential data may be converted into displayable images using the unexp(1) command. Unexp should be used before using any tools that perform arithmetic on pixel values, or displaying the image. Unexp expects files containing exponential data to have an "exponential_data" picture comment.

SEE ALSO

unexp(1), rle_putcom(3), librle(3), RLE(5).

AUTHOR

John W. Peterson, based on code by Spencer Thomas.
University of Utah
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3 FLOAT_TO_EXP (3) November 10, 1987

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