c64img 3.1

Image processing and converter for C64 graphic formats

C64img is a python package which provides an abstraction layer for creating images which Commodore 64 understands. This is especially useful in converting images created on PC graphics tools, with C64 limitation in mind.

This project was inspired by PNG2HIRES_ v0.2 gfx format converter /enthusi (onslaught), which was initially used as simple graphics converter between PNG/GIF images to C64 hires (Art studio + executable). It evolved to bunch of modules, which have own purposes - from simply converting graphics, to generating data for C64 programs written in cross compilers, or even generating data for memory optimised animations out of sequence of images.

Image2c64

Image2c64 is a frontend program to c64img module, which can converts virtually any image supported by Pillow to C64 hires or multicolor formats. Best results are achieved with filetypes PNG or GIF.

As an input 320x200 (multicolor or hires) or 160x200 (mutlicolor) picture is expected. Mutlicolor pictures will be scaled down to 160x200. Picture will be converted to 16 colors. During that process some information can be lost, if used more than 16 colors.

Requirements:

• Python 2.7

• Pillow module

Installation

Like other standard Python pro programs, c64img provide a convenient way to install using setuptools, so the procedure will look like:

$ python setup.py install

or, pip might be used as well:

$ pip install -e /path/to/c64img_repository

or, you can grab latest stable version from pypi:

$ pip install c64img

finally, if you prefer to use virtualenv:

$ virtualenv -p python2 venvname
$ source venvname/bin/activate
(venvname) $ pip install c64img

After that, you should be able to access image2c64 script or import c64img module in Python interpreter.

Usage:

First of all, check up the switches program provides:

$ image2c64 --help

Besides fine-tuning options like -b/--border for selecting border color, -g/--background for selecting background color, it allows to select aprorpiate output format:

• multi - for pure data located at $6000

• hires - same, but for hires bitmap and colors ($2000)

• koala - multicolor bitmap in Koala format

• art-studio-hires - high resolution bitmap in Art Studio format (hires version)

Those formats should be passed using -f/--format parameter.

Furthemore two more switches can be used for output format:

• raw (-r, --raw) - this will produce four files (prefix is obtained from the input image file name, or by using -o switch for output):

  • prefix_bg.raw 1-byte file with background color,

  • prefix_screen.raw - screen colors (usually placed at $0400),

  • prefix_color-ram.raw - additional 3rd color (supposed to be placed at $d800)

  • and finally prefix_bitmap.raw - with bitmap matrix of the picture

• executable - produces prg which can be executed on emulator or real C64. Note, that this is just a image data and little displayer added to the image data.

For example:

• Convert PNG image to koala with detailed log:

  $ image2c64 -vv -f koala image.png

  Output will be written to image.prg.

• Convert GIF image to executable hires image, and write output to output.prg file:

  $ image2c64 -f hires -x -o output.prg image.gif

• Convert several images to raw data. Put the files in out directory:

  $ image2c64 -f multi -r -o out image.png image1.gif image2.gif image3.gif

Parameter -v/-verbose can be use multiple times (effective, maximum amount is double v) which increase verbosity of the output. Using -q/--quiet have opposite effect - it will suppress the output.

Color clashes

Script can make several things in case of color clashes. In C64 graphics modes you cannot put pixels in as one like, since there was hardware limitations (memory, processing power etc), which provided to restrictions in graphics modes. For example, in standard hires mode (320x200) it is impossible to use more than 2 colors in 8x8 pixel area.

Underneath, c64img provides several options for color clash situation. By using -e/--errors switch with one of the following parameter, user can influence conversion process in case of clashes/errors:

• no parameter or none - raport it on the console

• show - will display it - every wrong area will be marked with red rectangle

• save - will produce file with suffix _error.png next to original file

• grafx2 - will save the error file, and open grafx2 image editor with original image in front screen and error image on the spare screen. This is useful for manual clash corrections. Executable grafx2 must be reachable by the environment variable PATH.

• fix - will try to fix the clashes. Note, that this method is pretty naïve - the approximation of the colors is coarse, and may produce strange results.

Example of output for save and fix arguments for --error parameter:

$ ./image2c64 -f multi -x -e save test_images/clash.multi.png
ERROR: Too many colors per block in char 10, 11 near x=76, y=84.
ERROR: Too many colors per block in char 11, 13 near x=84, y=100.
ERROR: Too many colors per block in char 12, 15 near x=92, y=116
$ ./image2c64 -f multi -x -e fix test_images/clash.multi.png
WARNING: Cannot remap color; using background - 'Light green'
$

Changes

• 2018-06-12 Added information about possibility to convert picture to chars (no conversion! Just an info in log!)

• 2015-09-10 Rearranged repository into separate modules for maintainability

• 2014-11-16 Added mechanism for automatic clashes fix

• 2014-11-11 Fixed issue with color clash check in multicolor

• 2014-11-11 Added grafx2 option into error param. In such case image will be opened in grafx2 program alongside with the error pic on spare screen.

• 2014-02-09 Rewrite the core of the converter (introduced char abstraction), added ability to convert sequence of images.

• 2012-11-20 Added executable output format for multicolor

• 2012-11-19 Added multicolor support, changes to the docstrings

• 2012-11-18 First public release

Licence

This software is licensed under 3-clause BSD license. See LICENSE file for details.