1. Forum
  2. USENET
  3. comp.sys.apple2

  • ][-Pix, a new Double Hi-Res image converter

    From kris.k...@gmail.com@kris.kennaway@gmail.com to comp.sys.apple2 on Monday, March 15, 2021 13:59:14
    From Newsgroup: comp.sys.apple2

    I'd like to announce ][-Pix, a new tool for converting images to Double Hi-Res format.
    https://github.com/KrisKennaway/ii-pix/
    The main features are:
    - image conversion takes advantage of NTSC artifact colour, using one of two colour models:
      1) Double hi-res colour produced by 4-pixel sequences.  This matches the double hi-res implementation used by some emulators, e.g. Virtual ][.
      2) Simulating NTSC chroma blending over 8-pixel sequences.  This more closely matches the behaviour of the NTSC signal and effectively allows access to additional double hi-res colours (85 in the simple model currently used).  This gives better image quality for targets that use a high-fidelity NTSC emulation (e.g. OpenEmulator), or real hardware.
    - performs N-pixel lookahead when dithering, i.e. optimizes over all 2^N pixel combinations to produce the best overall colour match.  This allows overcoming the limitation that once the pixels to the left of a given pixel have been chosen, that pixel only has two possible colours (since double hi-res colours are determined by the on/off state of the pixels to the left), neither of which may be optimal.
    - supports all standard source image formats.
    For more information, sample image conversions and comparison to other DHR converters, see the documentation at the above link.
    Please let me know if you have any questions, comments or suggestions!
    Kris
    --- Synchronet 3.18b-Win32 NewsLink 1.113
  • From Michael 'AppleWin Debugger Dev'@michael.pohoreski@gmail.com to comp.sys.apple2 on Friday, March 19, 2021 09:41:02
    From Newsgroup: comp.sys.apple2

    On Monday, March 15, 2021 at 1:59:16 PM UTC-7, k...@gmail.com wrote:
    I'd like to announce ][-Pix, a new tool for converting images to Double Hi-Res format.
    https://github.com/KrisKennaway/ii-pix/

    Fantastic work! Thanks including comparison images and doing the write-up. That brute-forcing all 2^N pixel combination is an interesting idea!

    Too busy with current projects but definitely keeping this on my radar as I'm curious about playing around with some different Perceptual Quality metrics.
    i.e. I do a fork and do a Photoshop/GIMP image "difference" to see what pixels are different, etc.

    m.
    --- Synchronet 3.18b-Win32 NewsLink 1.113