Png2prg converts a 320x200 image (png/gif/jpeg) to a c64 hires or multicolor bitmap, charset, petscii, ecm or sprites prg. It will find the best matching palette and background/bitpair-colors automatically, no need to modify your source images or configure a palette.
Vice screenshots with default borders (384x272) are automatically cropped. Vice's main screen offset is at x=32, y=35. Images in sprite dimensions will be converted to sprites.
The resulting .prg includes the 2-byte start address and optional displayer. The displayers can optionally play a .sid tune.
This tool can be used in all buildchains on all common platforms.
Png2prg 1.8 introduces multiple image optimization techniques to improve the pack ratio of output images. See 'Brute Force Mode and Pack Optimization' below.
Multicolor charsets of multiple frames is now supported. See testdata/charanim for an example.
Png2prg is not a tool to wire fullcolor images. It needs input images to already be compliant with c64 color and size restrictions. In verbose mode (-v) it outputs locations of color clashes, if any.
If you do need to wire fullcolor images, check out Youth's Retropixels.
koala: multicolor bitmap (max 4 colors per char)
hires: singlecolor bitmap (max 2 colors per char)
mixedcharset: multicolor charset (max 4 colors per char (fixed bgcol, d022, d023))
mccharset: multicolor charset (max 4 colors)
sccharset: singlecolor charset (max 2 colors per char (fixed bgcol))
petscii: singlecolor rom charset (max 2 colors per char (fixed bgcol))
ecm: singlecolor charset (max 2 colors per char (4 fixed bgcolors), max 64 chars)
mcsprites: multicolor sprites (max 4 colors)
scsprites: singlecolor sprites (max 2 colors)
mcibitmap: 320x200 multicolor interlace bitmap (max 4 colors per char/frame)
Png2prg is mostly able to autodetect the correct graphics mode, but you can also force a specific graphics mode with the -mode flag:
./png2prg -m koala image.png
Bitmap: $2000 - $3f3f
Screen: $3f40 - $4327
D020: $4328 (singlecolor only)
D800: $4328 - $470f (multicolor only)
D021: $4710 (multicolor only, low-nibble)
D020: $4710 (multicolor only, high-nibble)
You can supply one 320x200 multicolor image with max 4 colors per 8x8 pixel char per frame of which at least 2 are shared (the D021 and D800 colors).
Or supply both frames in regular koala specs (-interlace flag required). When making screenshots in vice, please disable the d016 pixel shift manually.
./png2prg -i testdata/madonna/frame_0.png testdata/madonna/frame_1.png
./png2prg testdata/madonna/cjam_pure_madonna.png
D800: $5800 - $5be7
Screen: $5c00 - $5fe7
Bitmap1: $6000 - $7f3f
D021: $7f40 (low-nibble)
D020: $7f40 (high-nibble)
D016Offset: $7f42
Bitmap2: $8000 - $9f3f
./png2prg -i -d016 1 testdata/mcinterlace/parriot?.png
Screen1: $9c00 - $9fe7
D021: $9fe8 (low-nibble)
D020: $9fe8 (high-nibble)
D016Offset: $9fe9
Bitmap1: $a000 - $bf3f
Bitmap2: $c000 - $df3f
Screen2: $e000 - $e3e7
D800: $e400 - $e7e7
By default charsets are packed, they only contain unique characters. If you do not want charpacking, eg for a 1x1 charset, please use -no-pack.
With ECM -bitpair-colors can be used to force d021-d024 colors.
NB: individual d800 colors are not supported with -no-pack.
./png2prg -m sccharset testdata/hirescharset/ohno_logo.png
./png2prg -m petscii testdata/petscii/hein_hibiscus.png
./png2prg -m ecm testdata/ecm/xpardey.png
./png2prg -m ecm testdata/ecm/shampoo.png
./png2prg -m ecm -bpc 2,7,14,0 testdata/ecm/orion.png
Charset: $2000-$27ff (omitted for petscii)
Screen: $2800-$2be7
D800: $2c00-$2fe7
D020: $2fe8
D021: $2fe9
D022: $2fea (ecm only)
D023: $2feb (ecm only)
D024: $2fec (ecm only)
Png2prg tries to figure out the right -bitpair-colors and auto-corrects where it can, but there still are edge-cases like the ones below. If an impossible color is found, an error will be displayed. Swap some -bpc colors around and retry. There can also be cases where manual -bpc colors can influence char-count or packed size.
./png2prg -m mixedcharset testdata/mixedcharset/hein_neo.png
./png2prg -m mixedcharset testdata/mixedcharset/huntress.gif
./png2prg -m mixedcharset -bpc 3 testdata/mixedcharset/shine.png
./png2prg -m mixedcharset -bpc 0 testdata/mixedcharset/charsetcompo.png
Charset: $2000-$27ff
Screen: $2800-$2be7
D800: $2c00-$2fe7
D020: $2fe8
D021: $2fe9
D022: $2fea
D023: $2feb
If the source image size is a multiple of a 24x21 pixel sprite, the image is considered to contain sprites.
The image will be converted from left to right, top to bottom.
./png2prg image.png
./png2prg -m scsprites image.png
./png2prg -m mcsprites image.png
Sprite 1: $2000-$203f
Sprite 2: $2040-$207f
...
By default, png2prg guesses bitpair colors by itself. In most cases you don't need to configure anything. It will provide a mostly normalized image which should yield good pack results, but your miles may vary.
To give you more control, you can force/prefer a specific bitpair color-order. Use c64 colors, so 0 for black, 1 for white, 2 for red, etc.
The following example will force background color 0 for bitpair 00 and prefer colors 6,14,3 for bitpairs 01,10,11:
./png2prg -bitpair-colors 0,6,14,3 image.png
It's also possible to explicitly skip certain bitpair preferences with -1:
./png2prg -bitpair-colors 0,-1,-1,3 image.png
Each frame will be concatenated in the output .prg. You can supply an animated .gif or multiple image files.
If multiple files are added, they are treated as animation frames. You can also supply an animated .gif. The first image will be exported with all framedata appended. Koala animation frames start at $4711, hires at $4329.
The frame files are following this format. Each frame consists of 1 or more chunks. A chunk looks like this:
.byte $03 // number of chars in this chunk
// $00 marks end of frame
// $ff marks end of all frames
.word bitmap // bitmap address of this chunk (the high byte is <$20)
.word screen // screenram address (the high byte is <$04)
For each char in this chunk:
.byte 0,31,15,7,8,34,0,128 // pixels
.byte $64 // screenram colors
.byte $01 // colorram color (koala only)
... // next char(s)
... // next chunks
.byte 0 // end of frame
... // next frame(s)
.byte $ff // end of all frames
Each frame consists of 1 or more chunks. A chunk looks like this:
.byte $03 // number of chars in this chunk
// $00 marks end of frame
// $ff marks end of all frames
.word screen // screenram address (the high byte is <$04)
For each char in this chunk:
.byte $03 // character
.byte $01 // colorram color
... // next char(s)
... // next chunks
.byte 0 // end of frame
... // next frame(s)
.byte $ff // end of all frames
The -d or -display flag will link displayer code infront of the picture. By default it will also crunch the resulting file with Antonio Savona's TSCrunch with a couple of changes in my own fork.
All displayers except for sprites support adding a .sid. Multispeed sids are supported as long as the .sid initializes the CIA timers correctly.
You can use sids located from $0e00-$1fff or $e000+ in the displayers. More areas may be free depending on graphics type. A memory usage map is shown on error and in -vv (very verbose) mode.
If needed, you can relocate most sids using lft's sidreloc.
Zeropages $08-$0f are used in the animation displayers, while none are used in hires/koala displayers, increasing sid compatibility.
By default png2prg 1.8 does a pretty good job at optimizing the resulting prg for crunchers and packers. It is not enough to beat SPOT 1.3.
The optimization techniques used by png2prg are also responsible for cleaning up the bitmap, making it ideal for animations and color effects.
Iterates are over many -bitpair-colors permutations automatically, packs with the built in TSCrunch and selects the shortest.
./png2prg -bf image.png
The -brute-force mode can be used in combination with additional flags.
Disable counting of bitpairs per color to guess a bitpair for a color.
./png2prg -bf -nbc image.png
Disable lookback to previous char's charcolors to guess a bitpair for a color.
./png2prg -bf -npcc image.png
Since TSCrunch is optimized for speed, packing with Dali can give varying results. This is also the reason for not including these options in the brute force permutations automatically.
The koala otpimizing thread on csdb has gained some interest in the scene. Since Sparta released SPOT it has been the best optimizer available.
Png2prg 1.8 has improved optimization techniques but requires -brute-force mode to beat SPOT 1.3. Manual flags can optimize even better in some cases.
All koalas are packed with Dali 0.3.2.
+---------+--------+----------+------------+--------+
| spot1.3 | p2p1.8 | p2p1.8bf | p2p1.8best | p2p1.6 |
+---------+--------+----------+------------+--------+
| 7332 | 7372 | 7332 | 7324 | 7546 | Untitled/Floris
| 5136 | 5190 | 5149 | bf | 5464 | Song of the Sunset/Mermaid
| 5968 | 5998 | 5963 | bf | 6155 | Short Circuit/Karen Davies
| 3618 | 3647 | 3616 | 3589 | 3830 | Portrait L+D/Sander
| 5094 | 5080 | 5083 | 5078 | 5320 | Weee/Mermaid
| 7497 | 7471 | 7458 | bf | 7612 | Deadlock/Robin Levy
| 8068 | 8097 | 8046 | 8038 | 8227 | Room with a view/Veto
| 7445 | 7490 | 7432 | bf | 7582 | Vangelis/Talent
| 6759 | 6739 | 6737 | bf | 6963 | Temple of Tears/Hend
| 7859 | 7848 | 7839 | 7821 | 7998 | Thanos/JonEgg
| 4859 | 4849 | 4782 | bf | 4983 | Solar-Sonar/Leon
| 5640 | 5671 | 5613 | bf | 5869 | Cisco Heat/Alan Grier
| 6243 | 6286 | 6228 | bf | 6430 | Daylight/Sulevi
| 2850 | 2884 | 2848 | bf | 3092 | Yie Ar Kung Fu/Steve Wahid
| 6727 | 6721 | 6730 | 6711 | 6901 | Lee/The Sarge
| 7837 | 7828 | 7798 | bf | 7960 | Parrot/Mirage
| 4559 | 4536 | 4494 | bf | 4821 | Dragon's Lair
| 4275 | 4324 | 4292 | 4284 | 4519 | Scorpion/SIR'88
| 5562 | 5558 | 5506 | bf | 5668 | Hatching/Joe
+---------+--------+----------+------------+--------+
| 113328 | 113589 | 112946 | 112853 | 116940 | Total
+---------+--------+----------+------------+--------+
- p2p1.8: default png2prg result w/o options
- p2p1.8bf: -brute-force mode
- p2p1.8best: hand-picked -bitpair-colors, or bruteforced with -npcc and/or -nbc flags
- p2p1.6: default png2prg 1.6 result w/o options
This release contains examples with all assets included for you to test with. Also included are the assets of Évoluer by The Sarge and Flotsam. A larger set of testdata can be found in the github repo.
Png2prg was built on Linux, building on Mac should work out of the box. For Windows, try out Windows Subsystem Linux (WSL), works pretty well. However, natively building on Windows should be easy enough, look at Compiling without Make below.
The compiled displayer prgs are included in the repo to ease building and importing png2prg as a library. Java is only required to build the displayers with KickAssembler (included in the repo).
But first install Go 1.20 or higher.
go install -v github.com/staD020/png2prg.git@master
git clone https://github.com/staD020/png2prg.git
cd png2prg
make -j
Build for all common targets:
make all -j
go build ./cmd/png2prg
In your Go project's path, go get the library:
go get github.com/staD020/png2prg
In essence png2prg implements the io.WriterTo interface. Typical usage could look like below. A more complex example can be found in the source of the cli tool.
import (
"fmt"
"io"
"github.com/staD020/png2prg"
)
func convertPNG(w io.Writer, png io.Reader) (int64, error) {
p, err := png2prg.New(png2prg.Options{}, png)
if err != nil {
return 0, fmt.Errorf("png2prg.New failed: %w", err)
}
return p.WriteTo(w)
}- Add gfxmode to .sym files and display in terminal output (thanks Spider-J).
- Add petscii animation support.
- Add -no-anim flag disable mccharset animations and store frames as separate screens.
- Add sccharset animation support and move separate screens to -no-anim.
- Add mixedcharset animation support and move separate screens to -no-anim.
- Bugfix: handle blank ECM images as well as ECM images using few bg colors (thanks Brush).
- Add -no-fade flag for koala animations.
- Improve crunchiness by re-using the previous char's bitpair-colors.
- Add -no-prev-char-colors flag to disable re-use of the previous char's bitpair-colors, in some cases this optimization causes worse pack results.
- Add -brute-force mode to find bitpair color combinations with better crunchiness. Burns some CPU for a couple seconds.
- Add -no-bitpair-counters flag to disable using bitpair counters per color for color guessing.
- Added multi-frame support for mccharset, where all frames use the same charset.
- Add support for any centered fullscreen image resolution bigger than 320x200 and other than 384x272.
- Add support for Marq's PETSCII tool .png resolution 352x232 (thanks jab).
- Bugfix: docs fixes related to installation from source (thanks jab).
- Bugfix: hide findECMColors log behind -verbose mode (thanks jab).
- Docs fix: add a bit more info for sprites (thanks fungus).
- Added -mode mixedcharset for mixed multicolor/singlecolor and individual d800 colors per char.
- Modified -mode sccharset to use individual d800 colors per char.
- Added -mode petscii.
- Added -mode ecm.
- Added -no-pack-empty to skip packing empty chars to filled chars to re-use for different colors. Only for mixed and ecm charsets.
- Added -force-pack-empty for singlecolor and multicolor charset, may save a char, but usually pack-ratio is worse due to increased d800 color usage.
- Improved auto-detection of graphics modes, including various charset modes.
- Added sid support to charset displayers.
- Added fullscreen fade in/out to charset displayers.
- Bug Fix: -force-border-color for singlecolor charset (thanks Raistlin).
- Bug Fix: do not write empty .prg file on error.
- Standardized d02x colors in output.prg for charset modes.
- Support for even more far-out palette ranges (thanks Perplex).
- Now throws an error if the palette can't be detected properly, this should never happen. Please let me know if you run into this error.
- Separated library and cli tool.
- Library supports the standard io.Reader and io.Writer interfaces.
- Patched TSCrunch further to increase crunch speed and use less memory.
- Added -parallel and -worker flags to treat each input file as standalone and convert all files in parallel. Gifs with multiple frames are still treated as animations.
- Stop relying on .gif filename extension, detect it.
- Add -alt-offset flag to force screenshot offset 32, 36), used by a few graphicians. Though, please switch to the correct 32, 35.
- Add -symbols flag to write symbols to a .sym file.
- Interlace support for mcibitmap (drazlace and truepaint).
- Bugfix: allow blank images input (thanks Spider-J).
- Allow colors not present in the image as -bitpair-colors (thanks Map).
- Added displayer for koala animations.
- Added displayer for hires animations.
- Added -frame-delay flag for animation displayers.
- Added -wait-seconds flag for animation displayers.
- Fixed bug in koala/hires displayers not allowing sids to overlap $c000-$c7ff.
- Expanding wildcards: using pic??.png or pic*.png now also works on Windows.
- Set bank via $dd00 in displayers.
- Added fullscreen fade in/out to koala and hires displayers.
- Added optional .sid support for koala and hires displayers.
- Added optional crunching for all displayers using TSCrunch.
Png2prg was created by Burglar, using the following third-party libraries:
TSCrunch 1.3 by Antonio Savona for optional crunching when exporting an image with a displayer.
Colfade Doc by Veto for the colfade tables used in the koala and hires displayers.
Kick Assembler by Slammer to compile the displayers.
Go by The Go Authors is the programming language used to create png2prg.
-alt-offset
use alternate screenshot offset with x,y = 32,36
-ao
alt-offset
-bf
brute-force
-bitpair-colors string
prefer these colors in 2bit space, eg 0,6,14,3
-bpc string
bitpair-colors
-brute-force
brute force bitpair-colors
-cpuprofile file
write cpu profile to file
-d display
-d016 int
d016offset (default 1)
-d016offset int
number of pixels to shift with d016 when using interlace (default 1)
-display
include displayer
-force-border-color int
force border color (default -1)
-force-pack-empty
optimize packing empty chars (only for sccharset)
-fpe
force-pack-empty
-frame-delay int
frames to wait before displaying next animation frame (default 6)
-h help
-help
help
-i interlace
-interlace
when you supply 2 frames, specify -interlace to treat the images as such
-m string
mode
-memprofile file
write memory profile to file (only in -parallel mode)
-mode string
force graphics mode to koala, hires, mixedcharset, sccharset, mccharset (4col), scsprites or mcsprites
-na
no-anim
-nbc
no-bitpair-counters
-nc
no-crunch
-nf
no-fade
-ng
no-guess
-no-anim
disable charset animations and store frames as separate screens
-no-bitpair-counters
do not use c64color bitpar counters optimization
-no-crunch
do not TSCrunch displayer
-no-fade
do not use fade in/out for animation displayers
-no-guess
do not guess preferred bitpair-colors
-no-pack
do not pack chars (only for sc/mc charset)
-no-pack-empty
do not optimize packing empty chars (only for mc/mixed/ecm charset)
-no-prev-char-colors
do not look at the previous char's bitpair-colors, in some cases this optimization causes worse pack results
-np
no-pack
-npcc
no-prev-char-colors
-npe
no-pack-empty
-o string
out
-out string
specify outfile.prg, by default it changes extension to .prg
-p parallel
-parallel
run number of workers in parallel for fast conversion, treat each image as a standalone, not to be used for animations
-q quiet
-quiet
quiet, only display errors
-sid string
include .sid in displayer (see -help for free memory locations)
-sym
symbols
-symbols
export symbols to .sym
-targetdir string
specify targetdir
-td string
targetdir
-v verbose
-verbose
verbose output
-vv
very verbose, show memory usage map in most cases and implies -verbose
-w int
workers (default 12)
-wait-seconds int
seconds to wait before animation starts
-workers int
number of concurrent workers in -parallel or -brute-force mode (default 12)