Conference hydra::amiga_v1

2993.0. "GIF to IFF/HAM converter Avail" by CGOFS::DREW (Steve Drew) Fri Oct 06 1989 14:14

        Well, I  had  so  much  fun  writing  the XIFF to HAM, that I
        decided to go for a GIF to IFF/HAM converter. 
        
        Anyway - its  done  -  ,  - it works -.  It gives much better
        results than HAMGIF viewer,  and  you  end up with a standard
        IFF file.  I also compared it to SHAMVIEW, which is a pain in
        the neck to use (ie GIFTOTMP  then  UNLACE then SUPERCON then
        finally you run SHAMVIEW to see the  image)  and it seemed to
        reveal  that  SHAMVIEW  (multiple  color  pallattes)  did not
        noticably improve the HAM image as well as only being useable
        from SHAMVIEW.
        
        Since there is well over a 1000 GIF pics on the NET, I'm sure
        this  will provide some great pictures to view.  I'm  in  the
        process of converting many GIF's (avail from CSCMAS, PC notes
        files etc...)  to IFF.  If there is sufficient demand I could
        make these available for after hours copying.
        
        *** The ZOO file  contains  an  Amiga  executable  AND  a VMS
        executable of GIF2IFF.  ***

                CGOU01::AMNEW:GIF2IFF.ZOO
        
        Heres, the DOC file: 
        
        Have fun.... Steve.
        

        -----------------------------------------        
        GIF2IFF  Version 1.0, (c) Steve Drew 1989
        
        This utility will convert any GIF file to an amiga IFF image.
        It supports all Amiga resolutions including HAM and overscan.

        The HAM  conversion  I've  found produces better quality than
        HAMGIF viewer and  still  equal or better than SHAMVIEW.  And
        the resultant output file  is  a  standard  ILBM image usable
        with any viewer or paint program.
        
        The  HAM  conversion process is  slow,  and  may  take  10-15
        minutes to convert a large 256  color  digitized GIF image to
        HAM.  For normal IFF 16/32 color pictures the conversion only
        takes a minute or two to produce the IFF file.
        
        Usage: 
        
            GIF2IFF -options input_file output_file 

        Options:

           -a n     Width aspect number, skip every nth pixel (Def=0)
                    This is automatically set to 2,  for  640  by 400
                    256  colors in order to correct the aspect  ratio
                    for a 320 by 400 HAM image.
                     
           -z       Disable  overscan  mode.

           -f       Retain full input size (no clipping). Will allow 
                    for upto  1024 by 1024 output image.  May only be
                    readable by a few paint programs.

           -s       Show input gif file size and format only, then exits.

       Ham conversion options:

           -d       Do Dithering

           -e       Show  HAM   color  generation  error  summary  on
                    completion.  Upon  completion, a summary is given
                    as to how close the original pixel by pixel color
                    values  where  recreated using the  HAM  encoding
                    method. See example below.
        

           -t n     Error threshold for creating next color register (Def=5)
                    The HAM color map is generated on  the  fly,  and
                    each color register created  is  valued  0-15 for
                    each RGB gun.  By default a new color register is
                    defined each time a pixel is  processed  whos RGB
                    value  minus  the  closest color register created
                    thus far is created than 5.  The  best values are
                    found to be in the range of 3-8.
        
           -i n     Add intensity value (Def=0).  Add this base value
                    to  boost  the  intensity of the picture.    (Not
                    usually needed).

           -n       Disable  color  rounding.    Since  the input 256
                    color pictures  have color values in the range of
                    00-FF, they must be converted  to  00-0F  for the
                    amiga color map.  A value  such  as 89 is rounded
                    to 09.  With the -n option this is masked instead
                    and would result in (for the above example) 08. 
                    Masking  (-n)  sometimes  removes  any  scattered
                    bright spots (pixels) in the picture.                    

           -p       Do 2 passes,  for  best  color  generation.  This
                    will  increase  the time  for  creating  the  HAM
                    picture but does help improve the end result.

        Files included in ZOO:
        ----------------------
        
                GIF2IFF,        ! AMIGA executable
                GIF2IFF.DOC,    ! This file
                GIF2IFF.EXE     ! VAX VMS executable
                SAMPLE_16.GIF   ! 16 Color GIF image
                SAMPLE_256.GIF  ! 256 Color GIF iamge, will convert to HAM 



        Example run of GIF2IFF, on a 256 color gif file:
        ------------------------------------------------

1> GIF2IFF -p -e neato.gif neato.iff

GIF2IFF: Version 1.0
Input GIF File is   : 320 by 200, 256 colors (197 used) : neato.gif
Creating IFF Picture: 320 by 200, 256 colors, (HAM) : neato.iff

HAM Completion  Summary
-----------------------
Color Threshold value: 5
Color Map Error Rate : 6630
Last Newcolor on line: 109
Color registers used : 16
Pixels in Error      : 4359   [6%]
Pixels errors > 3    : 370    [0%]
Pixels errors > 6    : 0      [0%]
Average Error value  : 1
Pixles fixed 2nd Pass: 4413

-----------------------------------------------------------------------
        
        For questions, or comments I can be reached at:
        
        ARPA : <drew%[email protected]>
        ENET : CGOFS::DREW
        Phone: 403-295-4357
        
        Enjoy,
        
        Steve Drew.
        
-----------------------------------------------------------------------
        
        

    re .0:
    Thanks! exactly what I've been looking for.  I'm interested in the
    resulting iff pics too.
    
    Do you know of any color HAM IFF to GIF converters?
    
    thanks,
    dennis

>    Do you know of any color HAM IFF to GIF converters?

        Your in luck,
        
        CGOU01::AMNEW:AMGIF.ZOO
        
        Contains AMGIF & AMGIF.DOC. I have not tried this but the doc
        says it supports most amiga resolutions to GIF including HAM.
        
        You can't go too wrong with 16 or 32 colors. However the HAM
        encoding method can very subjective to the algorithims that
        the conversion program is using.
        
        Since I haven't tried this one, I don't know how well it works
        but give it a try.

    /Steve.
    

Re: .0

>It gives much better results than HAMGIF viewer,  and you end up with
>a standard IFF file.  I also compared it to SHAMVIEW, ... and it seemed to
>reveal  that  SHAMVIEW  (multiple  color  pallattes)  did not noticably
>improve the HAM image as well as only being useable from SHAMVIEW.

I believe you!  When I saw the SHAMVIEW pics I was unimpressed: I'd
seen much better HAM pics (from Fish disk 196) that were the result of
doing the work to pick a good initial palette.  I got the idea that the
SHAMVIEW author was using brute force (dinking color registers) when he
should have been working smart.

From reading your docs, it looks like you're working smart, and putting
in the effort to pick a good color palette.

    Ok, I'll ask...How does one pick a good pallette?
    
    dennis
    

    re .2:
    CGOU01::AMNEW:AMGIF.ZOO
    
    Sounds great from the AMGIF.DOC description, but AMGIF either tells
    me "stack overflow" or guru's my 1meg A1000 when I give it more stack
    (tried 10000 and 50000).
    
    Has anybody succeeded in getting AMGIF working?
    
    thanks,
    dennis