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47 lines
1.9 KiB
Markdown
47 lines
1.9 KiB
Markdown
# Full-color
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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.
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## About
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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 #$06FA, with the leftmost zero nibble being ignored on the IIgs.
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To approximate it here, we use imagemagick to perform the following conversion steps:
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- resize the image to 320x67 - because IIgs resolution is 320x200 and we want it 1/3 height so CEILING(66.66666)
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- crop it into 67 images - each sized 320x1 - still all full color
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- for each line:
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- remove two channels (Green,Blue) to get remaining channel (Red)
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- reduce that channel to a 16 color, 12 bit, dithered image
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- recombine the 67 * 3 images into single 320x201 image
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- crop to 320x200, effectively dropping the last Blue line since we start with RGB at the top
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## Prerequisite
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You must have imagemagick installed. To see if it's installed, open a command line and type `convert`
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If you need to install it, for Mac OSX, I'd suggest `brew`:
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```$ brew install imagemagick```
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Linux - RHEL/CentOS
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```$ sudo yum install ImageMagick```
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Linux - Debian/Ubuntu
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```$ sudo apt-get install imagemagick```
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## Running the script to build an image
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Basically you can just run the `slicer.sh` script against any image that imagemagick supports.
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```./slicer.sh my_picture.png```
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## Running the test suite
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From the parent directory (the one this readme file is in), run the test script:
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```$ ./tests/run_1.sh```
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Output will be generated in the **out/** directory.
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Here are some samples generated by the test suite:
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