Capturing and Recycling AppleWin DHGR (Double Hi-Res) "Screen-Grabs" - A Tutorial

[Bill Buckels]

This document (see link below) is a tutorial about capturing, editing, and
otherwise recycling Apple II DHGR (Double Hi-Res) screens using AppleWin and
Windows Paint, and 2 utilities that I have extensively re-written for the
occasion: A2FCBMP and BMPA2FC

http://www.aztecmuseum.ca/AppleWinDHGRScreenGrabs_2013.pdf

This tutorial is likely to surprise some readers... producing it in
conjunction with re-writing my DHGR utilities certainly surprised me, and I
didn't exactly just fall out of an Apple Tree...

Here's the thing... I was struggling with working-around AppleWin's cosmetic
rendering of the color DHGR display which really fouls-up an accurate
aquisition of a DHGR image, when I realized that in double hi-res mode on
the Apple II, the high-bits are not used.

So I took a 560 x 384 grab of a complex DHGR screen of Monarch Butterfly in
AppleWin's monochrome mode and reviewed the bit pattern. It is a perfect
copy of both banks of visible DHGR memory in a raster-oriented format double
scaled in the vertical axis. The rest was relatively easy.

But I am not going to give-away the happy ending of all of this... you'll
just have to read my latest epistle to find-out more.

The A2FCBMP and BMPA2FC utilitities descibed in the tutorial run well in
DOSBox under Windows Xp (Windows 7 and Linux remain untested at the moment)
, and in native-mode MS-DOS and in a Windows Xp cmd Window. These have been
improved greatly over the last two releases with Apple33 Aztec C65 for DOS
3.3. They're not really even the same programs.

Over the next day or two I will finish the documentation for these utilties
and release them as well, with some other goodies including Source Code and
Demos and stuff, as I work towards the long awaited (by me) 2013 Update to
the AppleX Aztec C65 MS-DOS/Windows cross-compiler for the Apple II and
ProDOS 8.

I trust this brings everyone up to date, and while you wait for more, I hope
this tutorial will prove somewhat informative. Now if I could figure-out how
I am going to process captured Double-Lo Res Screens in AppleWin I would be
even more happy. If any AppleWin user has any thoughts on this, run a Double
Lo-Res program in AppleWin 1.22 and then let me know how you would do it...

I might even offer a prize to anyone who can. If you do accept the challenge
keep in mind that the invisible hi-bit is actively used for the high nibble
in DGR.

Regards,

Bill Buckels