pachde Imagine - New "sound from image" module

I’m just starting out with building modules for Rack, and I wanted share my early ideas for a module I’ve named imagine.

“pachde” is my brand, formed from the first two letters of my given, middle, and family names. Pronounced “patched” or “patch dee”, hence the logo: #d, because # looks to me like a patch on clothing.

This module loads an image (you know, a png or jpg), and lets you set up one or more read heads. Each read head generates control signals – gate, trigger, and v/oct. I’m leaving direct audio generation to other modules. You can think of it as an eccentric sequencer, rather than an oscillator.

Sketch of the UI

Controls in reading order

  • The blue area displays the image you’ve selected.
  • The circle with crosshairs suggests the read head. (graphic here likely to change – I need to think about how to set initial position.
  • There is room for this set of inputs and outputs to show 3 read heads.
  • Buttons+inputs for Reset (go back to starting position) and Play/Pause.
  • Click the “mountain and moon” icon to Open an image file.

Then, three rows for read heads. Number may vary in final module. Additional read heads may be possible with a future extension module. (Possibly a premium plugin, if I decide to go that route). To keep the UI uncluttered, this prototype hides unused read heads behind panels. Double click the “gripper” to remove the read head cover. Read heads with cables, and the first read head can’t be covered. Might be too cute an idea and more than needed for MVP.

I’ve read the debates about screws vs no screws. I lean to no screws to reduce the visual noise, but I understand people want it to look like something physical like you might see in a EuroRack, so I’ve taken a middle position and put nice caps on my screws. I might even make it possible to remove the caps and show the screws in all their slotted glory for the die-hards who like screws. Binary menu options are simple.

Read heads

  • Read head shape: circle or bar. Circle samples the image for a given radius around the read head position. The bar reads a small vertical rectangle of the image.
  • Inputs for x/y position of the read head. Protocol TBD, maybe 0-10V or 0-1V for position in proportion to image dimension, maybe selectable in right click menu.
  • Knob+input for read head Size. Knob is attenuation when a cable is connected, otherwise absolute size.
  • Knob+input for read head Step (or Speed). Signal protocol TBD.
  • Knob+input for read head Skip. This produces a gap or spread when the read head reaches a boundary.
  • Knob for Path (or “orbit”). This selects from a number of ways a read head could traverse an image. When you have cables on the x/y inputs, Step, Skip, and Path are ignored. Possible selections: Scanlines (left to right, top to bottom), Other scanning-type paths: RLBT, LRBT, TBLR, BTRL,…), Boustrephon (alternating left to right then right to left scanning down, Circular, Album (spiral in, like a vinyl record). Pong (randomized bouncing at the edges), etc. Might need some controls to set a trajectory for some paths, like starting point and angle, then a toroidal (wrapping) at image edges. I can start simple then figure out the UI for other ways of getting around.


  • Straightforward Gate, Step, and V/Oct output jacks.
  • Knob to select data used to generate the signal. Possible values include any of the fundamental components of a pixel in various coding schemes: Luminance, Lightness (from HSL), Value (from HSV), Hue, Saturation, RGB Ave, etc. Gate and trigger happen when a value crosses a threshold looking at previous and next samples of the image. More sophisticated edge detection may be required or useful. Might need a knob for threshold/sensitivity.

Example use case

Imagine your image is rows of bar codes defining rhythm patterns. For this use case you want the bar read head shape, a size matching the height of the bar code, a skip for the gap between rows, and the Scanline path. V/Oct output is unused.

So, what do you think?


this looks very promising :+1:

1 Like

Love the idea. To me a square read head makes more sense as in a certain pixel radius, but it sounds like it will be a cool module.

1 Like

Can’t wait to see how a dollar bill sounds, or the Mona Lisa …

If you output HSV you can convert it with this:

maybe having permanent HSV outs would be good?

The output knob will let you choose the value going to the V/Oct. With 3 read heads you can have them all on the same path and choose the H, S, V (or L*ab, HSL, RGB, Luv…) component for the 3 outputs. it might be useful to provide a switch for a normalled inputs – where 1 read head feeds all 3 outputs.

There are too many possible components to provide outputs for them all on the module surface, unless I provide only a single read head.

I didn’t see a doc link for Sparkette’s module, so I don’t know the ranges it expects for the inputs. 0-10v? Are there other modules that want color components for input?

Might do a square read head, too. Particularly useful when you’re manually designing an image for precise control, and using a small size 1-8 pixels averaged.

The circular makes more sense for large images (like landscape photos), and as suggested by the circle’s gradient. I’m imagining circular gaussian-weighted sample centered at the x/y pos with a radius given by the size knob/input.

I haven’t written any of the sampling yet, so it’s hard to predict what sampling technique will give the most useful results. Much will depend on the size and nature of the input image, so I want to provide option, with a reasonably clean UI.

This looks like it’ll be a nice tool. Thanks Paul. What do you think of getting it to load animated .png or .gif files? The only module I know that can load an animated gif is computerscare’s, but it’s purely a visual panel. VCV Library - computerscare Custom Blank

It feels a lot like wave terrain synthesis, but without direct sound output. Here I scan a terrain with two circles so you get a continuous spiral scan. Or scanning a textured Klein Bottle to get a continuous loop in 3D.

Did you ever see Loco Modules? Those do a lot of what you describe, but they’re limited to PNG files 256×256 pixels maximum.

@cosmoproductions – Good idea! Animated formats could be supported. I can image a number of ways to use them, either advancing the frame when the current frame has been fully traversed, or by scanning all frames before advancing the position. I can add this to the backlog – I want to get to MVP first to see if I can get musically useful information from images using simple methods.

1 Like

@existentia - Thanks for the reference to Loco TEX – from the description it appears to be a very simple version of the idea here. I looked in the Rack library and didn’t find it.

At the moment I’m focusing on control information via relatively naive methods before advancing to audio-rate spectral processing. That’s higher-level DSP+math that I’ll need some time to digest ;-).

I’m interested in hearing about what types of signals would be most useful on both inputs and outputs: Unipolar 0-10V, bipolar -5-5, 0-1V? CIEE color standards are usually 0-1.0 floating point values, but easily converted to any of these voltage ranges.

Finally, haha. I think I even wrote about this kind of idea in my “wet dreams” thread, haha (aka ideas for any interested developers) or somewhere else. I don’t even remember now.

Can’t wait to play with this thing

1 Like

That thread inspired me a bit to keep working on the ideas!

1 Like