Conference hydra::amiga_v1

I know of a tool called VIRTGIF (should be on a 2xx Fish I think). It shows the GIF's (almost) 
immediatly. The only drawback is that the results are not as good as what you would get with,
say, GifMachine. Gifmachine have really great output files (in SHAM). VIRTGIF works in HAM-inter-
lace (320*200), but I don't recall if you can scroll across the pic.

If you only want to see the GIFS, use Virtgif, if you want to enjoy the pics, GIFMaschine should 
be your choice. (or any other good GIF Converter).

byebye,
sammy
----- 

    I use Vpic on the IBM side to view Gifs, but always use the Art
    Department Pro. to convert for viewing on the Amiga. You hear a lot
    about GIF's exceptional pic quality from the PC clone owners. and they
    do look nice on the Decstation here at work. However GIF will support
    256 colors in hi res. The Amiga supports 16 colors in hi res and this
    has always been a point bought up by the other pc owners. I get a lot
    of what is the monitor pitch, or how many dots across etc from these
    camps. Well after converting many pics I can say that ham mode fairs
    very well against GIF. My feeling are that computer graphics have risen
    above the how many dots of resolution stage. My classic answer is a
    question I ask. "whats Wrong With That Picture". as the pc owner is
    looking at a dynamic Ham pic. (4096 colors in hi res).The point is that
    resolution is like beauty it is in the eye of the beholder. I save the
    dot stuff for discribing overscan(this eludes many clone owners) where
    it should be applied . You have to remember graphics goes beyound one
    static image on screen. Another point is that to get GIF from your
    clone you have to add a graphics card and an expensive monitor, this is
    not needed for the Amiga. For this cost you could get HamE, or DCTV and
    these will blow the Gif pics away hands down. I just last night
    converted a .TIFF(better than gif) pic to 24 bits, and loaded it into
    the Toaster at System Eyes, and it looked great. Sorry about this long
    disertation but when I see remarks like those in .0 it fires me up.
    	When it comes to graphic imaging, in termsof available display
    modes(without added boards) and number of colors supported(excluding
    24bit products) the amiga excells. Wehn it comes to animating these
    graphics the Amiga is half way around the track while the Dos, Mac
    owners are still in the starting blocks.
    								bill 

I've got 2 packages called gif2ham and gifmachine.

I'll try and remember to upload them

:^)

Greg

    Just in case you might want to know :
    
    On Tape::amiga:[upload]
    you can find Hamsharp14.lzh
     That's the one I use. Changes GIF to HAM. It's not fast, but
     powerfull. 
    
    
    							Erik	

    There is one aspect of GIFS of the amiga that annoys me.
    
    I use HAMGIF on my 3000 to display GIF pictures before I decided wether
    or not to convert them using Art Department Pro.
    
    The thing is IBM PC owners (even 286 10MHZ ones) can display a GIF
    picture in around a second whereas on my 3000 is takes about10-20 secs
    for the small ones. Is this mearly a fact that no-one has optimised gif
    viewers on the amiga to take advatage of it's plus ot what. I would
    also like to see a gif viewer that utilizes that Floating Point
    Processor to really speed things up.
    
    Flame off.
    
    Shaun.
    

    re .5
    
    	I seems you do not understand what a GIF viewer is doing. First,
    GIF pictures are defined in the format, resolution, and colors that
    a IBM PC can display. So on a IBM system viewing a GIF picture is just
    moving disk data to video memory. The AMIGA video modes are not
    compatible with VGA. The AMIGA must convert the colors and image size
    to match a AMIGA video format. This conversion takes time. You should
    also understand that the converted Amiga image will never look as good
    as the GIF file does on a IBM PC. You need to start with a higher
    resolution, more color image than either can display and convert down
    to the best mode of each system.
    
    		Steve P.
    

    I understand that because 99.99% of Gif files are created with IBM's
    that to display them on the amiga that the covert the colors and screen
    resolutions but I did not think that it would take that long.
    
    Since gif files by there nature are compacted using the same compaction
    routines as .lzh files that maybe this is where the speed loss is ??
    
    BTW, it's not really a BIG problem as Art Department Pro converts the
    images pretty fast and it takes less time as any other
    display/convertor that I have seen.
    
    Shaun.
    

    RE .6
    
    You're wrong to suggest that displaying a GIF file on a PC clone is
    just a matter of moving the data from disk to video memory hence the
    speed. A GIF contains compressed data so a great part of the time taken
    to display the picture is spent decompressing the data before it is
    displayed on the screen.
    
    
    
    				Jamie.

Re: .4

I would guess that the problem is encoding the picture into HAM mode.
The HAM video mode on the Amiga can be thought of as a compression
scheme: it takes a 12 bit plane display and compacts it down to
6 bits.  Part of this compression is picking the values to be stored
into the sixteen color registers that ham uses, since all the pixels
in the images will be stored in terms of its relationship to one of the
color registers.  Picking the right color register values is an
optimization problem.

The steps involved in displaying a GIF picture that has 256 colors in
HAM mode would be:

1.  Unpack the GIF file into memory.

2.  Look at every pixel in the image.  Pick 16 colors such that every
    pixel in the image can be described as:

	1.  One of the sixteen colors.

	2.  The color of the pixel to the left with one of its red, green,
	    or blue components modified.

    Since this encoding will result in some of the pixels not having their
    original color, you have to pick 16 color register values that minimize
    the number of pixels that get encoded with the wrong color.  (Pixels
    with the wrong color can look like brightly colored confetti appearing
    at the boundary between two different colors.)

3.  Create a new version of the image in memory that encodes each pixel
    as a function of one of the sixteen color registers.

4.  Display the new results.

Step 2 is hard.  In fact, if you do step 2 by trying out every color
combination in the color registers, the Amiga would have to consider
6.3 times 10 to the 57th power combinations.

Be glad that someone has optimized the GIF viewers to be smarter than
brute force.