Presentation

Coagula is an image synth. This page comprises all available documentation at present.
Note: The program is in deep alpha state, so there may be any number and kind of bugs. Please report any problems you get (that are related to the program). Also, I'd like some input on features and the interface ­ which features are less convenient to use, and what more should be implemented.

The version of Coagula available from this page is freeware. There will always be a light version with limited functionality, but to get the full version you will have to pay some fee. The price is not set yet, and it will depend on the deals with software distributors. See below for intended features of the full version.

System requirements: You need Windows 95 or later.
A monitor which can show thousands of colors is highly recommended.

Go directly to download ­ Current version is Coagula Light v 1.01, compiled on Dec 24, 1998.

Getting started         Editing the image         Rendering         Features         Download

Getting started. Principle of operation.

The quickest way to understand how Coagula works is to start the program, make some marks on the empty (black) canvas, and render a soundfile. Open the resulting WAV file (Coagula.wav) with your favourite soundfile editor and play it. You will probably quickly make the connection between the image and the output sound. (Figurative pictures will usually not connect with the output sound in any interesting way ­ but do whatever you like.)

 

How the image is interpreted

Each picture element (pixel) on your screen has three component colours: Red, green and blue. Each pixel in the image represents a sine wave at a certain time, frequency and stereo placement (when doing stereo output):
• The vertical position of a pixel decides the frequency, while horizontal position corresponds to time.
  You can of course set the playing time and frequency range for the generated sound. See below.
• Red is sent to left channel, while green controls amplitude of the right channel. Yellow, in this colour scheme, is composed of equal intensity of red and green, and will thus be sent to both channels, resulting in centered output.
• Blue is presently not used, but will be used for spectrum control. See feature plans below.

Editing the image. Tools.

Coagula can only read and save BMP images. All images that are opened for editing will be converted to 24-bit.
The attraction of the program, if any, lies partly in the tools used to edit the image. The point of the tools is of course to facilitate image editing which will be sonically meaningful. Thus, there are some features less common in other image editing programs (or never seen before). Lots of stuff that would be really useful is also missing. But you can save the image to disk and open it in your favourite real image editor. After editing, save in that program, switch back to Coagula and select "Refresh" under the File menu to immediately reload the image from disk (or just hit the "R" key). This should make it feasible to disfigure your pictures productively.

There are some features in the program which are not visible to the eye. Here is an overview of the main tools and secret commands.

Painting and selection
Use left mouse button to apply the brush, and right mouse button to select an area.
Extend selection by holding down the SHIFT key on your keyboard when right-clicking the canvas. This allows for selection of areas which are larger than the screen.
All operations (except rotations) are applied to the selected area.

Rotation
Use Control+Left mouse button and drag to zoom and rotate the image.
Use Control+SHIFT+Left mouse button and drag to skew-flip the image (this is a parallelogram pseudo-rotation).
Both these operations will use the initiating mouse-click spot as point of origin.

And
a tip

Filters and overlays
You can use a BMP file as a filter on the image you are presently editing. The filter image will be stretched to fit the selected area (or the full image), then the pixels of the two images are multiplied. Try it to see the effect, the point here is just that "filters" and "images" are the same thing, and may be edited, rendered, saved as files and used interchangably.
To help creating new filters, you may apply the brush options to the entire current selection. (The shortcut key is ENTER.) This is useful for creating smooth gradients.

When you use an image as an "overlay", the pixels are added to the present image. You can use this to resize an image: Create a new (black) image and open another as overlay. You can also cut/copy and paste any (part of an) image as an overlay. Image data pasted from the clipboard will also be fitted into the current selection.

Image browsing
In later versions there will probably be some way to browse filters and images. For now you will have to resort to the following old tip on editing the Registry to get some hint about what filters look like:

Open Regedit. Find the key HKEY_CLASSES_ROOT/.bmp. Check the "Default" value. It will be something like "Paint.Image". Now locate that value under HKEY_CLASSES_ROOT. Open or create the key "DefaultIcon" under that value. Set the "Default" value for this key to the string value "%1" (no quotes). Restart your computer to effect the change.
This will make all bmp images show as their own icons in the file open and close dialogs. Note that this change will affect all of your operating system, so all bmp images everywhere will be shown as their own icons in Explorer. You may or may not like it.

 

The Brush toolbox has a few obscure controls:



The brush uses two colours. They are selected in the palette, using the left and right mouse buttons, resp.
You can compose colours by holding down the SHIFT key while selecting a new colour with the right or left mouse button. The selected colour will be added to the present one.
As mentioned, the brush can be applied to the selected area by hitting ENTER.

In the Color mix section you select how the brush colour is mixed with the colours already present in the image. "Filter" will increase the intensity of image colours, if the brush colour is brighter than half intensity, else the image colours will be faded. Try it eg with a half dark, half bright brush, on an image with large coloured areas.
You can also apply the brush parameters to the current selection. This is useful to create gradients for new filters.

The Echord section copies the brush to the right and above the mouse pointer position. The "Hop" sliders control X/Y (pitch/time) offsets, respectively. The "n, x" sliders control number of repetitions, (left slider), and a multiplication factor for the hops (right slider), making the hops gradually longer or shorter (or downright bent).

The Color boiler is also hidden in the Brush toolbox:



If you click the "Boil" option button a new set of parameters are revealed. These control cellular automata-type options which allow some involved colour manipulation as well as blurring. This leans more to the eyecandy side of things than towards usefulness, but I wanted to try it out, so there...

There are three independent things you can do here: Add or subtract a value to the image colours, cycle the image colour components (red, green, blue), and blur the image.

Amount of effect: The selected brush colours will be used to control how much each colour component is affected by the boiler. If the brush is red and blue, the green component will not change.
Boiling: The "°c" slider (top left) sets a positive or negative value to add to each colour component. Colour values are wrapped, so if you add more than the maximum intensity (or subtract to less than zero), the colour will jump to the opposite extreme.
Colour cycling: The "Clr" slider (lower left) controls how much the colour components will "bleed" into each other. If the brush is blue and the image has red and green, some blue will be added to those pixels.
Blurring: The two right-side sliders, "blr" and "->", control amount and direction of blurring.

Apply to selection: For maximum confusion, this effect may also be run on the whole image (or the current selection) from a menu option, under "Edit | Color Operations." (Don't forget the keyboard shortcuts now, a choppy animation can be had by holding down the "C" key.)
When used from the menu, the brush colours will still be used ­ stretched ­ to control the amount of effect in the selection.

The Echord toolbox is perhaps a little more straightforward.



The "Hop", "Num" and "Fade" sliders should be self-explanatory. The "1st" slider sets the hop for the first echo/overtone. The "Mul" slider will make the hops gradually shorter or longer. The "Rnd" slider controls hop length randomness for each pixel, resulting in a smeared/noisy image.
The "Swap r/g" and "Alt r/g" checkboxes switch red and green colours, at the first hop, and at every hop, resp. This results in left-right bouncing echoes and correspondingly sends chord overtones into the opposite stereo channel.
"Wrap" will make echoes continue over the right edge of the image and come back from the left. This is useful for creating looped sounds. ("Wrap" has no effect on chords however.)

Image options. Rendering the image.

The frequency range and total time of the output sound is set in the "Image Options" dialog under the Render menu. You can set any frequency range and time, and also the size of new images. The frequency of each line in the image is a function of the height of the image and the selected frequency range.

Tip: To get one semitone step between each line you must calculate the appropriate values, and set the image size and frequency range accordingly. (There will be some controls to do these calculations for you, in later versions.)
Eg 7 octaves = 84 semitones. So set height to 85 (adding the topmost octave note to simplify frequency calculation). Each octave is a pitch doubling, so if you want to tune middle A to 440 Hz, set the freq range to eg min = 55, and max = 7040. To use quarter-tones you just double the height of the image (almost: 7 × 24 + 1 = 169), and use the same frequency range.
Coagula is perfectly useful this way, but you will probably find it rather fiddly to edit the image for tonal creations. The author prefers to use it with a rather more dense spectrum, ie to use it as an intuitive tool for additive synthesis.

Amplitude: Coagula attempts to guess the maximum output amplitude and make the output soundfile as loud as safely possible. The routine looks at the pixels and attempts to find max amplitude, but it is a little simplistic, and so does not work for all sounds. You can change the base amplitude factor manually in the "Image Options" dialog.

Features and plans.

Recent features:

Dec 18-24, 1998:
• The brush options can now be applied to the selected area in the image. This is useful for creating gradients for new filter images.
• Zoom-rotation and skew-flip now use mouse pointer as origin, not just the center of image.
• Some bug fixes.

Nov 14, 1998:
• 15-20% faster rendering engine.
• New brush mode: Boiler. Runs cellular automata on the canvas as you move it. See above for usage notes. When this mode is selected, the lower left corner of the Brush dialog will show control parameters for boiling rather than for brush Echord.

Some features in the retail version of Coagula, which will not be implemented in the light version:

• Playback of the generated soundfile.
• Analysis of soundfiles, creating an image from any WAV.
• Blue is used to control the spectrum of any red/green signal at the same pixel. As the intensity of blue increases, the waveform of the affected oscillator will sweep from sinewave into a narrow noise band, so that white (pink, turquoise) areas in the image will yield a dense spectrum.

Helper and productivity features.

Some of the following will also go into the freeware version:
• Thumbnail browser for filters and stored images.
• Multiple Undo levels.
• Facilities to simplify pitch control, help to design speech formant frequency filter images and whatnot.
• Reading Csound Hetro and/or Pvanal files.
• Toolbars for some of the commands.
• Some kind of MIDI output. Not sure how this should work.
 
Check the ones you prefer and nudge me if you have some strong priorities. More suggestions welcome.

Registration. Download section.

When the full-featured version is ready, there will be a link to the distributor here.
If you want to be notified about updates you can mail me.

Get Coagula Light, v 1.01 (Dec 24, 77 kB packed)
Download a zip file with some images suitable as filters (File date: Sept 16 1998, Size: 277 kB).
Unpack these images into the "Coagula\Filters" folder.

If you like Coagula, you may want to try GranuLab.

 
Senast ändrad: 24:e dec 1998
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rasmuse@hem.passagen.se