FastBlur - fast approximate Gaussian blurs

[wonkey_monkey]

FastBlur v0.3.1
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• 0.3: added threads parameter
• 0.3.1: enabled clamping to avoid rounding error overflows

Having been frustrated one too many times by VariableBlur's GaussianBlur and its bizarre syntax (and wildly variable speed), I've now written FastBlur, which performs an approximately Gaussian blur by repeated box blurs. It's much faster than GaussianBlur by default, and still at least 1.5x faster than GaussianBlur with multi-threading enabled (FastBlur is multi-threaded by default).

It also doesn't suffer from GaussianBlur's long start-up times.

It supports all colour spaces and can optionally dither the output. It's also (approximately) gamma-aware, which means more visually-pleasing blurs (although this should be disabled if you're blurring a mask).

Edit: now includes hopefully complete source code. Actually compiling/linking it is left as an exercise for the reader.

FastBlur
========

Fast Gaussian-approximate blur for all colour spaces.


Usage
=====

FastBlur(
  (clip)
  (float)
  (float)    y_blur
  (int)      iterations   = 3
  (bool)     dither       = false
  (bool)     gamma        = true
)


Parameters
==========

[float]:
    Blur radius (equivalent to PhotoShop Gaussian Blur's radius)

y_blur:
    Vertical blur (if different from horizontal blur)

iterations:
    Number of iterations for approximation. Defaults to 3. A value of 1 performs a box blur.

dither:
    Enable/disable dithering

gamma:
    Approximate gamma awareness. This should be disabled for masks.