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Manual Reference Pages  - readgif (3m_pixel__readgif)

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NAME

readgif(3f) - [M_pixel__readgif] read a GIF file (LICENSE:PD)

CONTENTS

Synopsis
Description
Options
Example
Authors
License

SYNOPSIS

subroutine readgif(filename, num_image, image, iostat, color_map, verbose)

   character(len=*), intent(in) :: filename
   integer, intent(in)          :: num_image
   integer, intent(out), allocatable :: image(:,:)
   integer, intent(out)         :: iostat
   real   , allocatable, intent(out) :: color_map(:,:)
   logical, intent(in), optional :: verbose

DESCRIPTION

read the num_image’th gif image from filename into arrays image and color_map

OPTIONS

filename
	input file
num_image
	number of image required
image	Image data returned
iostat	I/O error number, =0 if ok
color_map
	RGB for each level, range 0.0 to 1.0
verbose
	[char46]true.for verbose output

EXAMPLE

Sample program:

      program demo_readgif
      use M_pixel__readgif, only : readgif
      use M_pixel__writegif, only : writegif
      implicit none
      character(len=*),parameter :: filename=’boxes.gif’
      integer                    :: num_image=1
      integer,allocatable        :: image(:,:)
      integer                    :: iostat=0
      real,allocatable           :: color_map(:,:)
      integer,allocatable        :: color_map2(:,:)
      logical                    :: verbose=.true.
      integer                    :: i,ii,jj
      call readgif(filename,num_image,image,iostat,color_map,verbose)
      if(iostat.ne.0)then
         write(*,*)’*demo_readgif* could not read GIF file ’,trim(filename)
         stop
      endif

      write(*,*)’SIZE OF IMAGE =’,size(image)
      do i=1,rank(image)
         write(*,*)’RANK OF IMAGE=’,i,size(image,dim=i)
      enddo

      write(*,*)’SIZE OF COLORMAP=’,size(color_map)
      do i=1,rank(color_map)
         write(*,*)’RANK OF COLORMAP=’,i,size(color_map,dim=i)
      enddo

      ! convert between colormap types
      ! writegif uses an integer colormap, values 0 to 255
      ! readgif  uses real values 0.0 to 1.0
      ii=size(color_map,dim=1)
      jj=size(color_map,dim=2)
      if(allocated(color_map2))deallocate(color_map2)
      allocate(color_map2(ii,0:jj-1))
      color_map2=255*color_map

      ! change color and write standard gif file
      where (image.eq.1) image=4
      call writegif(’boxes_new.gif’,image,color_map2)

      end program demo_readgif

AUTHORS

Jos Bergervoet, Van Snyder, Maurizio Cremonesi, Clive Page, and others

LICENSE

This module contains a subroutine readgif(3f) which can read GIF files of types Gif87a and Gif89 (and maybe others). The code comes from various authors, see comments below. This version was put together by Clive Page who has put it into the public domain.

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Nemo Release 3.1

readgif (3m_pixel__readgif)

April 21, 2023

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