An image based MIDI sequencer - Dave Noyze

A novel approach to MIDI sequencing using an arbitrary image source and an arbitrary XY scanning function. The selected image can be manipulated in a number of ways. The system can create a realtime MIDI data stream or record to a MIDI file. Its inspiration comes from a sound synthesis method known as terrain scanning. This is a different approach to the left to right image synthesis system Metasynth.


The main part of this sequencer is a 512 by 512 pixel image area. This image is scanned by an XY function which reads the RGB colour values for the purposes of creating MIDI note, velocity and duration events.

The first step is to drag a folder of images (JPEG, GIF, PICT) onto the image area. The application then builds a user selectable menu of these image files. Once an image has been selected it can be manipulated in a number of ways. The image can be zoomed in or out, and moved around the X and Y. Quicktime blending modes can be used with any background colour to blend with the picture.

The scanning cursor’s shape, colour and size can be modified to account for different image types, and allows for easier viewing of current X/Y function location on the image.

The RGB values are extracted by any X/Y function (MOD width and height of the display area for functions exceeding the range). RGB or their inversions are mapped to Note, Vel or Dur via a scaling box. The Dur parameter is fed back to the metronome via a multiplier so the timing of the sequence is also variable. X/Y function has line mode, lines from last position to current position in user defined steps.