Context-
Oriented
Image
Processing
Didier Verna
Introduction
Genericity
Contexts
Optimization
Context-Oriented Image Processing
Reconciling Genericity and Performance through Contexts
Didier Verna
didier@lrde.epita.fr
http://www.lrde.epita.fr/˜didier
http://www.facebook.com/didierverna
@didierverna
COP 2015 – Sunday, July 5
1/21
Context-
Oriented
Image
Processing
Didier Verna
Introduction
Genericity
Contexts
Optimization
Introduction
The Common Lisp Image Manipulation Bundle
Climb
Highly generic image processing library
DSL / GML for complex image processing chains
Inspired by Milena (C++ / templates)
Genericity drawbacks
Performance degradation
Code cluttering / OO Design breakage
Agenda
Public: reconciling genericity and performance
Hidden (not so) : explore the benefits of a
multi-paradigm dynamic language
4/21
Context-
Oriented
Image
Processing
Didier Verna
Introduction
Genericity
Image Definition
Graph-Based Images
Processing Chains
Contexts
Optimization
Generic Image Processing
Abstracting images, neighborhoods, pixels etc
The duality of “pixels”
A value ? A location on a 2D grid ?
2 key concepts: sites and values
Image = f (site) → value
Site sets: (iterators) full images, neighborhoods etc
Values: (regular OO design) RGB, RGBA, bits, ints,
floats, 32, 64 etc
6/21
Context-
Oriented
Image
Processing
Didier Verna
Introduction
Genericity
Image Definition
Graph-Based Images
Processing Chains
Contexts
Optimization
Generic Image Processing
Abstracting images, neighborhoods, pixels etc
Generic Dilation Algorithm
(defun dilation
(image &aux (result (copy image)))
(do-sites (site (domain image))
(let ((max no-value))
(do-sites (neighbor (neighbors site))
(setq max (max max
(iref image neighbor))))
(setf (iref result site) max)))
result)
7/21
Context-
Oriented
Image
Processing
Didier Verna
Introduction
Genericity
Contexts
Optimization
Image Specificities
To be taken into account
Reasonably easy
Image formats, storage types, pixel values etc
Still, code cluttering (class proliferation)
Cross-cutting
Image properties
Orthogonal to regular specificities
Example: speed property for site access
I
slow
I
fast (O(1))
I
fastest (O(1) + pointer arithmetic)
I
Depends on both the image type and the site-set type
14/21
Context-
Oriented
Image
Processing
Didier Verna
Introduction
Genericity
Contexts
Optimization
Behavioral
Layering value classes
Layered static types
Layered RGB class
(deftype uint8-color () ’(unsigned-byte 8))
(deflayer uint8-color-value)
(define-layered-class rgb
:in-layer uint8-color-value (value)
((red :type uint8-color)
(green :type uint8-color)
(blue :type uint8-color)))
18/21
Context-
Oriented
Image
Processing
Didier Verna
Introduction
Genericity
Contexts
Optimization
Behavioral
Layering functions
Layered static types
Optimized algorithms
(define-layered-method make-grayscale
:in-layer uint8-color-value ((rgb rgb))
(declare (optimize (speed 3) (safety 0)))
(make-instance ’grayscale
:intensity
(the uint8-color
(round (the float
(+ (the float (
*
(red rgb)
0.299))
(the float (
*
(green rgb)
0.587))
(the float (
*
(blue rgb)
0.114))))))))
19/21
