add full-color script

full-color/readme.md

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+# Full-color 
+
+This is based off of a concept seen on early systems to simulate separate Red, Green, and Blue scanlines in order to approximate a higher number of colors. 
+
+## About
+In this case we are targeting the 12-bit color space on the Apple IIgs (2^12 = 4096).  It color system allows 4-bits per channel, meaning I can have a red value from 0-15, a green value from 0-15, and a blue value from 0-15.  In hexadecimal it looks like this #$06FA, with the leftmost zero nibble being ignored on the IIgs. 
+
+To approximate it here, we use imagemagick to perform the following conversion steps:
+
+- resize the image to 320x67  -  because IIgs resolution is 320x200 and we want it 1/3 height so CEILING(66.66666)
+- crop it into 67 images - each sized 320x1  - still all full color
+- for each line: 
+  - remove two channels (Green,Blue) to get remaining channel (Red)
+  - reduce that channel to a 16 color, 12 bit, dithered image
+  - recombine the 67 * 3 images into single 320x201 image
+  - crop to 320x200, effectively dropping the last Blue line since we start with RGB at the top
+
+## Prerequisite
+You must have imagemagick installed.  To see if it's installed, open a command line and type `convert`
+
+If you need to install it, for Mac OSX, I'd suggest `brew`:
+```$ brew install imagemagick```
+
+Linux - RHEL/CentOS
+```$ sudo yum install ImageMagick```
+
+Linux - Debian/Ubuntu
+```$ sudo apt-get install imagemagick```
+
+## Running the script to build an image
+Basically you can just run the `slicer.sh` script against any image that imagemagick supports.
+
+```./slicer.sh my_picture.png```
+
+## Running the test suite
+
+From the parent directory (the one this readme file is in), run the test script:
+```$ ./tests/run_1.sh```
+
+Output will be generated in the **out/** directory.

full-color/scripts/slicer.sh

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+#!/bin/bash
+
+IMAGE=$1                          # ./something/foo.png
+IMAGEBASE=$(basename $IMAGE)      # foo.png
+IMAGEBASENOEXT=${IMAGEBASE%%.*}    # foo
+OUTBASE=out
+OUTDIR=$OUTBASE/$IMAGEBASENOEXT
+
+
+mkdir -p $OUTDIR
+
+# start with RGB, so from 200 vertical pixels divided by 3 colors = 320x66.6 (we'll do 67 and remove extras)
+# also, we don't reduce colors yet, because we need 67 full-color lines to split into three separate
+# 4-bpc (12bit color) lines to composite at the end
+convert -resize 320x67\!  -crop 320x1 $IMAGE $OUTDIR/$IMAGEBASENOEXT-%03d.full.png
+
+for file in `ls $OUTDIR/$IMAGEBASENOEXT*.full.png`;
+do
+    echo Working on splice:  $file
+    filebase=$(basename $file)
+    filebasenoext=${filebase%%.*}
+    dither=Riemersma
+    convert -channel Green,Blue -evaluate set 0 +channel -colors 16 -depth 12 -dither $dither $file $OUTDIR/$filebasenoext.gs.0-R.png
+    convert -channel Red,Blue   -evaluate set 0 +channel -colors 16 -depth 12 -dither $dither $file $OUTDIR/$filebasenoext.gs.1-G.png
+    convert -channel Red,Green  -evaluate set 0 +channel -colors 16 -depth 12 -dither $dither $file $OUTDIR/$filebasenoext.gs.2-B.png
+done
+
+convert -append $OUTDIR/$IMAGEBASENOEXT*gs* $OUTDIR/$IMAGEBASENOEXT-FINAL.png
+convert -crop 320x200 $OUTDIR/$IMAGEBASENOEXT-FINAL.png $OUTBASE/$IMAGEBASENOEXT-FINAL-APPX.png

full-color/tests/run_1.sh

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+#!/bin/bash
+# run from parent dir "./tests/run_1.sh"
+for i in lion.jpg painting-swirl.jpg pink-cosmos.jpg radiant-color.jpg ;
+do
+    ./scripts/slicer.sh ../sample_images/$i
+done

readme.md

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+# Image Conversion Tools for the Apple IIgs
+This is a set of random utilities and convertors I've written over the years.  Each on is it's own directory here with a readme, so you'll have to click on the directories to see what a tool does.
+
+Currently I've only added a recently written tool, `full-color`.  I'll try to add others as I start scouring my archives and clean them up.