Importing common bitmaps

[Bill Brown]

>>ideally, we should have r.in.ppm since netpbm (pbmplus) is distributed
>>with grass. That way we don't need r.in.sunrast, r.in.tiff,
>>r.in.gif, etc. Am I correct in this thinking? Is there any instance
>>where ppm is not generic enough?
>
>I agree, but I did notice that converting from PICT -> ppm -> sunrast
>caused the lut's to get stuffed up a bit (this was in my Monash Uni
>incarnation a few months ago).
>
>Simon Cox

The lut's get "stuffed" because while PICT & sunrast use 8bit look up 
tables, ppm doesn't, using 8bits for each of Red, Green, & Blue to represent
"True Color" instead.  (Actually sunrast has a True Color flavor, but
the one r.in.surast accepts is the color look up table flavor.) 
Because ppm is "True Color", you can get all those colors you never see
on your 8bit screen from your "continuous" raster maps if you use r.out.ppm,
then send the ppm to a slide recorder or other 24bit output device.
So in the conversion from ppm to sunrast, the
look up table has to be inferred from a look at the color distributions
in the ppm, and depending on the algorithm used, this is probaly where
it gets messed up.  It would be better to go from PICT -> sunrast
directly, since both formats use look up tables. 

> However, I am unaware of any public domain "one step, all purpose" 
> converters (neither xv or alchemy are PD).
> ...
> --Darrell

And that give me a chance to plug MY favorite FREE image tools,
SDSC Image Tools, from San Diego Supercomputer Center, available at:
ftp.sdsc.edu via anonymous ftp 
in the directory: /pub/sdsc/graphics/imtools

This tool suite works with the following formats:

    bmp     Microsoft Windows bitmap image file
    cur     Microsoft Windows cursor image file
    eps     Adobe Encapsulated PostScript file
    gif     Compuserve Graphics image file
    hdf     Hierarchical Data File
    ico     Microsoft Windows icon image file
    icon    Sun Icon and Cursor file
    iff     Sun TAAC Image File Format
    mpnt    Apple Macintosh MacPaint file
    pbm     PBM Portable Bit Map file
    pcx     ZSoft IBM PC Paintbrush file
    pgm     PBM Portable Gray Map file
    pic     PIXAR picture file
    pict    Apple Macintosh QuickDraw/PICT file
    pix     Alias image file
    ppm     PBM Portable Pixel Map file
    pnm     PBM Portable aNy Map file
    ps      Adobe PostScript file (write only)
    ras     Sun Rasterfile
    rgb     SGI RGB image file
    rla     Wavefront raster image file
    rle     Utah Run length encoded image file
    synu    SDSC Synu image file
    tga     Truevision Targa image file
    tiff    Tagged image file
    viff    Khoros Visualization image file
    x       AVS X image file
    xbm     X11 bitmap file
    xwd     X Window System window dump image file

And yes, Darrell, it works with standard input/output.
These are the tools you get (imconv being the most useful):

    Tool            Description
    --------------- ------------------------------------------------
    imadjust        Adjust image colors, desaturate, brighten, etc.
    imcat           Concatenate images into multi-image files
    imcltroll       Cycle a color lookup table
    imcomp          Digitally composite images
    imconv          Convert between all supported image file formats
    imcopy          Copy a portion of an image into a new file
    imfile          Display image attributes
    imfill          Fill a region of an image with a color or gradient
    imflip          Flip an image horizontally or vertically
    imformats       Describe image file format support
    imgray          Convert to grayscale
    imhist          Compute an image histogram
    immono          Convert to monochrome
    impaste         Paste an image into another
    imroll          Cycle an image horizontally or vertically
    imrotate        Free rotate an image
    imscale         Scale an image up or down
    imshear         Shear an image horizontally or vertically
    imsplit         Split apart multi-image files

imconv is especially easy to use - if your image files have the right
extension, all you have to do is type:
imconv infile.ppm outfile.gif
and the conversion automagically happens, creating the new outfile.gif.
There are lots of options to these tools and so far there isn't much
I've found that they can't do (although read support for postscript 
would be nice).

> The disk space problem could be minimized if an r.in.ppm command
> worked on stdin. Then, if users would find it simpler, a bunch of
> scripts could be written for specific formats (e.g.,
>     #!/bin/sh
>     # r.in.gif (sans bells and whistles)
>     giftoppm $1 | r.in.ppm -
>     exit
> )
> 
> [disclaimer - I haven't had a chance to look at the contrib
> program that (Brown?) mentioned earlier - maybe it already
> does this.]
>
> --Darrell

The r.in.ppm I mentioned doesn't allow use of stdin, but that would be 
great.  I glanced at the code & it looks like it quantizes the colors it
finds in the ppm file to a maximum no. of colors of 32,768, which seems
like a reasonable number to deal with in a GRASS color file. (ppm files
could theoretically contain ~16 million different colors)  I don't
know who wrote this - it's from SCS - anybody out there who could 
accept credit/responsibility and verify this info?

- Bill B.

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Bill Brown				e-mail: brown at zorro.cecer.army.mil
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