RetroFW scaling demo

This demo shows the difference in quality between native 1:2 Pixel Aspect Ratio 320x480 and upscaled 320x240 resolutions.

Building

RetroFW

To build for RetroFW, run:

BUILDROOT=<path to buildroot> ./build-retrofw.sh

The package will be built at build-retrofw/scaling_demo.opk.

Host

To build for your host system, install SDL 1.2 and freetype2, then run:

mkdir -p build
cd build
cmake ..
cmake --build .

The binary will be built at build/scaling_demo.

Image DPI

lenna_128x256.png has its PNG pixel aspect ratio metadata set like this:

exiftool -PixelsPerUnitX=1 -PixelsPerUnitY=2 -PixelUnits=Unknown lenna_128x256.png

Additionally, we also set EXIF X/YResolution metadata:

exiv2 -m <(printf 'set Exif.Image.XResolution 72/1\nset Exif.Image.YResolution 144/1') lenna_128x256.png

This information is not yet used by the demo app.