Boston 2/boston-2.iso/DOS/GRAFIK/TOOLS/PIXFX/PIXFX.DOC

Text File | 1993-12-01 | 16KB | 428 lines

                           pixFX Documentation
                        Version 2.1  December 1990


                 Copyright (C) 1990  Golden Hind International
                            All rights reserved



 Introduction
 ------------

 pixFX is an IBM PC program for displaying GIF images from 2 to 256 colors
 on an SVGA 640 x 480 x 256, VGA, or EGA display system.  pixFX combines
 ease of operation with many new features previously not available in
 GIF viewers.  These features include:

 - pictures are automatically scaled to full screen size and displayed with
   the correct aspect ratio.

 - pictures using more than 16 colors such as scanned photographs are
   displayed with automatic contrast and brightness control, and automatically
    color-reduced if necessary.

 - many special effects are available, including photographic and digital
   image processing operations.

 - the special 360 x 480 x 256 color mode is supported on IBM compatible
   VGA displays.  Because of the automatic scaling, VGA users can see
   practically all GIF images in near Super VGA quality.

 pixFX is both educational and fun!


 Installation
 ------------

 To install pixFX, simply execute the archived program to extract the
 PIXFX.EXE module.  When executed pixFX will automatically detect which video
 hardware is available and use the mode which gives the best possible
 resolution.  In some cases pixFX may not correctly recognize the video
 hardware, in which case the video mode may be overridden by setting the
 PIXFX environment variable.  See the video modes section of this document
 for details.


 Operation
 ---------

 pixFX may be operated either from the DOS command line, or interactively.
 The format of the commands is the same in both cases.

 DOS command line:

 To display a GIF picture, issue the command:  pixfx [options] GIFfilename

 Example:  pixfx -b150 -m -v vga256 picture.gif

 Interactive:

 Invoke the program pixFX without any parameters.  A command line is
 displayed for entering options.  This command line may be edited with the
 left and right arrow keys, the Delete, Backspace, Home, and End keys.

 The GIF files in the current directory are displayed, and the currently
 selected file is highlighted.  If no file name is entered on the command
 line, the currently selected file is used.

 To select a particular file from the current directory, use the up and down
 arrows.  The Tab and Shift-Tab keys may be used to move between columns
 of the displayed directory.  The Page Up and Page Down keys are used to move
 between different pages of the displayed directory if it does not fit on
 one page.

 To switch to any other directory or drive, simply type its name by itself
 on the command line, e.g.  D:\GRAPH

 Options
 -------

 Options are provided for further control the operation of pixFX, and to
 product special effects.  Each option is a minus sign followed by a letter
 with no intervening space.  Some options require a numeric parameter,
 as shown in the list below.

 The format of the options list follows UNIX (tm) conventions - case is
 significant!  Options may be mixed in any combination.  pixFX can
 make sense out of unusual values of some parameters - e.g. a negative
 value or a very large value for contrast.  The possibilities are endless!

 Flags
 -----

 -h   halftone

      Halftoning is available for both monochrome (B&W) and color pictures.
      B&W halftoning uses only black and white to simulate all shades of
      gray.  Color haftoning uses 8 colors (black, white, red, blue, green,
      cyan, magenta, and yellow) to simulate all colors in all shades.

        (Pictures that are to be printed are normally halftoned because most
      printers can only place ink at full density on paper.  There are
      two basic methods of halftoning: the one most widely used in the
      printing industry uses dots of variable size; the other uses fixed
      size dots.  The second method is used in most printers attached to
      computers, and is becoming more popular.)

      pixFX V2.1 uses the well-known Bayer dithering matrices for halftoning.
      There are several other halftoning methods available based on
      a concept known as error diffusion. Because of the popularity of
      300 dpi laser printers there is a growing need for high quality
      computer algorithms for halftoning.  Golden Hind International is
      actively researching this technology.

 -i   information

      The dimensions of the GIF image and the number of colors are displayed
      on the status line.

 -m   monochrome

      Colors in the picture are converted into shades of gray, similar to
      B&W TV or a B&W photograph.  pixFX uses the television standard for
      monochrome conversion, the NTSC Y luminance component of a color picture.

 -n   negative

      Colors and shades of gray are inverted, giving the appearance of a
      photographic negative.  (Color photographic negatives include an
      orange mask, so they don't appear as true negatives.)

 -s   solarize

      When photographic film is highly overexposed, as for example by
      pointing at the sun, areas of high light intensity may end up dark.
      This characteristic is now used intentionally as a special effect
      known as "solarization".

      (For pixFX to solarize a picture, the contrast must be set at a value
      considerably higher than 100%.  Because most pictures with more than
      16 colors are displayed with an automatic contrast setting considerably
      greater than 100%, it is usually not necessary to specify a contrast
        setting.)

 -Y   false color

      The colors of the picture are intentionally changed:  green becomes
      red, blue becomes green, and red becomes blue.  False color is an
      image processing operation which can be used to bring out hidden
      aspects of a picture because the psychological link between objects
      and their normal colors is broken.  Infrared pictures are one form
      of false color.

 -Z   pseudo color

      Different shades of gray are displayed instead as different colors.
      Pseudo color can be used to bring out features in monochrome pictures
      that might otherwise be missed.

      (Because pseudo color only takes a monochrome input, pixFX will convert
      a color picture to monochrome first.)



 Parameters
 ----------

      All these options take a numeric value following the option, separated
      by a space.  Most options take an integer value.  This options which
      require a real value are specifically identified in the following
      list.

 -a   picture aspect ratio

      The picture aspect ratio is its width divided by its height.
      pixFX can usually determine a picture's aspect ratio, but sometimes
      it may be necessary to override this decision.

      For reference, the aspect ratio of the screen on a personal computer is
      4/3 or 1.333, the same as TV.  A different aspect ratio of 6/5 is
      common on workstations.  (Note that the aspect ratio of a picture is NOT
      always the number of pixel columns divided by the number of pixel rows.)

      If you want to test that your monitor's vertical height and
      horizontal widths are adjusted to their correct values, display a
      picture with the aspect ratio forced to 1.000 and measure the
      picture on the screen.

 -b   brightness

      This option sets the overall brightness of the picture.  The parameter
      is expressed in percent, with the default being 100% for 2-16 color
      pictures.  For 32-256 color pictures, the default brightness is set
      automatically, depending on the overall brightness of the original image.

      Automatic brightness adjustment is turned off for any image whose
      filename is of the form PIXFX*.GIF.

 -c   contrast

      This option sets the overall contrast of the picture.  The parameter
      is expressed in percent.  The default for 2-16 color pictures is
      100%, while the default for 32-256 color pictures is set automatically,
      depending on the overall contrast of the original image.  For many
      images, the default contrast setting will be in the range 150-175%.

      Automatic contrast adjustment is turned off for any image whose
      filename is of the form PIXFX*.GIF.

 -g   gamma

      Most cameras and monitors do not exhibit a linear response between
      light intensity and film density or electrical signal levels. This
      non-linearity is expressed as gamma, the exponent of the algebraic
      power relationship between light intensity and film density or
      electrical signal.

      Thus:
            film density = a * (light intensity) exp gamma

      The gamma option in pixFX applies an additional correction. The default
      is 1.0 - a value less than 1.0 reduces contrast, while a value greater
      than 1.0 increases contrast.  Gamma correction is carried out by pixFX
      before any other options.

 -o   ordered dither

      Each pixel has some ordered dither added to it.  The dither value is
      based on the 4 x 4 Bayer dithering matrix.  The maximum amount of dither
      is plus or minus 1/2 the parameter value (the R, G, and B component
      of each pixel is encoded in the range 0 to 255).

      Ordered dithering can be used to smooth transitions in images such
      as occurs in sky backgrounds and flesh tones.  The dithering is only
      applied to mid-range values.  See also the -r parameter.

 -p   posterize

      Posterizing is a special effect where a limited range of colors or shades
      of gray are used to display a picture.  The parameter specifies the
      number of levels to be used - 2, 3 or 4.

 -r   random dither

      Each pixel has some pseudorandom noise added to it.  (The pseudo-
      random noise on pixFX is "blue" noise, which has had the low
      frequency component removed for better appearance.)  The parameter
      specifies the total range over which an individual pixel can vary,
      based on black being 0 and white 255.

        Random dithering can be used to smooth out transitions in images and
      also to generate special effects.  (Try -p 2 -m -r 128.)
      The dithering is only applied to midrange values.  See also the
      -o parameter.  Random and ordered dithered can be used in combination
      if desired.

 -v   video mode

      See the separate section on video modes.

 -x   x offset

      This parameter is the x location in the picture corresponding to the
      center of the screen.  Allowable values are -100 to +100, with the
      default being 0.  The main use of this option is for pictures scaled
      at more than 100%.

 -y   y offset

      This parameter is the y location in the picture corresponding to the
      center of the screen.  Allowable values are -100 to +100, with the
      default being 0.  As for the x offset option, the main use of this
      option is for pictures scaled at more than 100%.

 -z   scale factor

      At the default value of 100% pixFX automatically scales each picture
      so that it fills as much of the screen as possible, while still
      maintaining the correct aspect ratio.  Pictures may also be displayed
      at more or less than full size by setting the scale factor option.

      The scale factor option is intended to be used in conjunction with the
      x offset and y offset options.  For example, the options:
        -x 100 -y 100 -z 300
      will magnify the picture 3 times, and place the top right corner of
      the picture in the exact center of the screen.

 -A   hue

      This parameter corresponds to the tint control on a color TV.
      Allowable values are from -100 to +100, with the default being 0.

      The hue option works by adjusting the equivalent NTSC I and Q
      color TV signal components.

 -B   saturation

      This parameter corresponds to the color control on a color TV.
      The default is 100%.  Setting saturation to 0 will generate a
      monochrome picture.

      Similar to the hue option, the saturation option works by adjusting
      the equivalent NTSC I and Q color TV signal components.


  The options for brightness and contrast of individual colors are grouped
  together below.  The default for these values is 100%.  Note that these
  values multiply the overall picture brightness and contrast values set by
  the -b and -c parameters.

 -C   red brightness

 -D   red contrast

 -E   green brightness

 -F   green contrast

 -G   blue brightness

 -H   blue contrast

 -I   yellow brightness

 -J   yellow contrast

 -K   magenta brightness

 -L   magenta contrast

 -M   cyan brightness

 -N   cyan contrast


 -X   pixelation

      The picture is subdivided into squares, with each square displaying the
      average color of the original picture.  (The picture appears as though it
      is being displayed with very coarse pixels, hence the name pixelation.)
      The parameter is the number of squares to be used along the width of
      the picture.  (Values of 20 to 40 give good results.)

      Note that this special effect is generated AFTER the original picture
      has been displayed.

 Video Modes
 -----------

 There are 3 ways of specifying which video mode pixFX will use to display
 images:

 If no mode is specified, pixFX will automatically detect the available
 hardware and choose the highest mode available - SVGA, VGA or EGA.  (Because
 of the automatic scaling performed by pixFX, the user normally does NOT need
 to specify the video mode needed to display any particular image.)

 The default video mode may be specified by setting the PIXFX environment
 variable, e.g. SET PIXFX=VGA256X

 The video mode may be set for an individual image on the command line by using
 the -v option, e.g. -v tseng  (Tseng SuperVGA adapter in 640 x 480 x 256 mode.)

 The video modes supported by pixFX are:

      ega       640 x 350 x 16 colors
      vga       equivalent to vga16 for 16 color images
                          and vga256 for 256 color images
      vga16     640 x 480 x 16
      vga256    320 x 200 x 256
      vga256x   360 x 480 x 256  (most VGA compatible adapters)
      svga      640 x 480 x 256  (autodetect type - must have at least 512K)

  Specific SuperVGA adapters may also be selected in 640 x 480 x 256 color mode:
      aheada, aheadb, ativga, chipstech, everex, oaktech,
      paradise, trident, tseng, tseng4, video7


 Appendixes
 ----------

 Release Notes
 -------------
 Version 2.1  December 1990.

      One page limitation on GIF directory display removed.  Ordered dither
      and random dither parameters added.  Miscellaneous bugs corrected.

 Version 2.0  December 1990.

      Support added for 256 color mode on most SVGA adapters with at least 512K
      of memory, and on VGA adapters, including the special 360 x 480 x 256
      color mode.

      Commands may be entered and edited interactively for files selected from
      a directory listing.

      On-line help system added.


 Version 1.0  October 1990.

      640 x 350 x 16 color display mode on EGA displays.

      Commands entered from DOS command line only.


 Trademarks:
 ----------

      pixFX is a trademark of Golden Hind International.
      GIF is a service mark of Compuserve Incorporated.
      IBM PC is a trademark of International Business Machines Corporation.
      UNIX is a trademark of AT&T.

 Distribution
 ------------

      The file PIXLZH.COM is a self-extracting archive containing the following
      files:

      READ.ME            Licensing and distribution information
      PIXFX.DOC          Instructions for installation and use (this file)
      PIXFX.EXE          Executable module of pixFX