8bitworskhop's Dithertron - mode 2 screen generation on your browser

handy tools that can assist in the development of new software
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scruss
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8bitworskhop's Dithertron - mode 2 screen generation on your browser

Post by scruss »

I was just on a session at KansasFest (the Apple II event, usually in Kansas City) that introduced me to the very neat 8bitworkshop online IDE. While the IDE doesn't (yet!) support the Beeb, its Dithertron graphics tool does. It only generates PNG images in Mode 2 format right now, but is still potentially useful:
moggy with squozed aspect ratio because modern
moggy with squozed aspect ratio because modern
morris_minor_convertible-bbcmicro.mode2.png (13.63 KiB) Viewed 1457 times
(Yes, it produces pixel-for-pixel utput, so the aspect ratio won't look right.)

The original image is here: https://mltshp.com/p/1J74Z
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dominicbeesley
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Re: 8bitworskhop's Dithertron - mode 2 screen generation on your browser

Post by dominicbeesley »

Nice idea for testing out stuff. Kind of jsfiddle for the c64. Do you know what c compiler it uses?
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mlouka
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Re: 8bitworskhop's Dithertron - mode 2 screen generation on your browser

Post by mlouka »

The perceptual colouring option combined with Stucki dithering algorithm is really impressive. Gives much better results that I would have though was possible with Mode 2 and the standard colour pallette. Nice to be able to quickly see the differences between so many dithering algorithms.
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hexwab
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Re: 8bitworskhop's Dithertron - mode 2 screen generation on your browser

Post by hexwab »

So I've been hacking on this a bit.

Thus far:

* Support for beeb screen modes 0,1,2,4,5 and AUG's "8" including export to their native framebuffer formats.
* Custom output sizes for all your overscan/underscan/whatever needs.
* Custom palettes with reordering (a bit wonky still[1]).
* Better aspect ratio support, including saving the aspect in exported PNGs[2]. Beeb PAR is 0.96, the same compromise b2 chose.
* Some UI improvements.

Try it at https://sphere.chronosempire.org.uk/~HEx/dithertron/ (may go away and/or stop working at any time)

Of course I had to make a picture disc. Pictures are all MODE 1 with no fancy palette tricks in the frankly insane resolution of 416×288 (borders are bad, mmkay?), for a framebuffer size of 29952 bytes. Since loading 29K files from disc is a real headache they are all compressed with exo's self-extracting thingy.

Not tested on real hardware.

Source:
https://github.com/hexwab/dithertron
https://github.com/hexwab/beebpics

Tom.

[1] To get a palette of your choosing: (1) turn auto palette on; (2) find an image or section thereof such that auto-palette picks the colours you want; (3) turn auto palette off; (4) drag the swatches until they're in the right order.

[2] Support for the pHYs chunk is a crapshoot but, e.g., gimp can display such images correctly by turning off "dot-for-dot" mode.
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