Grayscal V1.6a - February 11, 2002
Earle F. Philhower, III
earle@ziplabel.com
http://www.ziplabel.com/helio

These programs allow JPEG and BMP images of unlimited size to be
transferred and displayed on your Helio in 16 grayscales.

Please be sure to backup your PDA before running this application.

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What's New?

V1.6a lets the Helio auto-power off while viewing a picture

V1.6 adds scroll button support in file lists and synchronizes the
list view between display and file open.  It also adds back a working
delete button, no need to get DBUtility to remove old pictures.
(Thanks to Ryan CAsey for the scroll button snippets!)

V1.5 fixes unstoppable scrolling with large images, adds support for
next-image/last-image via the up/down keys, and adds a -NOBIG option
to the MAKEGRAY program to not include a large size image.

V1.4 adds a overview and zoom mode.  No more shrinking images to 160x160,
view images as big as your memory allows!  Newly converted files contain
a small overview picture, and a full-size image.  Click on the small image
to zoom in to full-scale, and tap in the corners of the screen to scroll
the zoomed in view.

Also added is a Floyd-Steinberg 16-color dithering routine, which removes
posterization (visible bands between color changes).  Image quality is
MUCH improved!

Finally, it will auto-resume zoomed in to wherever you were when your
PDA is powered off.

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Helio Installtion:
. If you have installed an older version of the software you need to
  delete it from your PDA before installing the new one.  Do this on
  your Helio by going to the "System Setup" program, hit the
  "System Information" option, hit "Delete Apps", select Grayscale
  and hit "Delete"
. Start helio desktop
. Right-click on the username to bring up popup menu
. Select "Install PDA Application"
. Select grayscale.app
. Hit the hotsync button and voila

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Making Grayscale Data Files:
a)  (the easy way)
. Create an 8-bit ot 24-bit BMP or JPG image.
. Drag the image file in Windows explorer onto the makegray.exe program
. A file ending in ".HDB" will be created in the same spot as your
  source image.

b)  (the hard way, but more customization)
. Create an 8- or 24-bit grayscale BMP/JPG file with your favorite
  application (MS Paint or Image Viewer is fine)
. From a command prompt, run makegray
      makegray input.bmp "Description" output.hdb
  ** Note, description must be 32 chars or less, spaces OK **
  ex:  makegray mrouge.bmp "Moulin Rouge" mrouge.hdb
. If you don't want the full-size image saved in your file, just
  add a "-nobig" to the command line, like so
      makegray -nobig input.bmp "Description" output.hdb
      makegray -nobig input.bmp

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Installing Data Files:
** There are sample .HDB files included in the Install directory **
. Copy the resulting HDB file to your hotsync upload dir:
     C:\Program Files\VTech\Helio Desktop 2.0\1\Acc
. Hotsync, and off you go

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Source Code:
Source code is available at http://www.ziplabel.com/helio
You will need to get my STDLIB library which handles all my ZHDB file IO,
also available at ziplabel.com.

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JPEG Credits:
This software is based in part on the work of the Independent JPEG Group.
(V6.2b of the jpeg library)

Dithering Credits:
I took the dithering code almost verbatim from an old HOWTO written by
Lee Crocker. 
( http://www.student.dtu.dk/~c971592/image/specs/dither.txt )

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Have fun.

Earle F. Philhower, III
earle@ziplabel.com
