I'm trying to experiment with image processing in haskell (with which
I haven't much experience). I've written some FFI code to talk to
the ImageMagick library which provokes a few questions (environment is
ghc 6.2.1 on debian):
1. Speed: I'm reading in a 2000x1500 pixel image, and have defined
John Kozak [EMAIL PROTECTED] writes:
data Pixel a = Pixel !a !a !a deriving Show
I use ImageMagick to load the image, then build an Array of Pixel
Floats. Building the array takes 45 seconds on a 2.5Ghz P4 with
code compiled -O2, which seems slow to me - are my expectations
If you are using GHC the fastest way I know to do this
is to build the array using a mutable-unboxed array in the
state-monad. Then freeze the array and return an
unboxed immutable array. This is a lot faster than
building the array by copying (every time you set a
value in an immutable array the
Oh... also when using unboxed arrays you may well have
to have a separate array for each colour plane (r,g,b,a)
as I think unboxed arrays can only contain primitive types - although
I am not certain about this - it may be enough to have the
contents strict.
Keean.
On Thu, 2004-07-01 at 12:34, MR K P SCHUPKE wrote:
Oh... also when using unboxed arrays you may well have
to have a separate array for each colour plane (r,g,b,a)
as I think unboxed arrays can only contain primitive types - although
I am not certain about this - it may be enough to have the
Yes, deriving unboxable would be nice... I think for images though
it is not too much of a problem to work with a record of arrays
rather that an array of records.
Keean.
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On 01 July 2004 11:53, John Kozak wrote:
I'm trying to experiment with image processing in haskell (with which
I haven't much experience). I've written some FFI code to talk to
the ImageMagick library which provokes a few questions (environment is
ghc 6.2.1 on debian):
1. Speed: I'm
Hi
I consider myself a pretty good imperative programmer, been at it for
decades, and am tryibng my hand at Haskell now. Unfrituantly I am not
getting it all that quickly despite having the multimedia haskell book.
To start ghetting some hands on, I thought iI owuld do something which i
have
Hi
I consider myself a pretty good imperative programmer, been at it for
decades, and am tryibng my hand at Haskell now. Unfrituantly I am not
getting it all that quickly despite having the multimedia haskell book.
To start ghetting some hands on, I thought iI owuld do something which i
have
On Thu, 2004-07-01 at 17:01, Crypt Master wrote:
I consider myself a pretty good imperative programmer, been at it for
decades, and am tryibng my hand at Haskell now. Unfrituantly I am not
getting it all that quickly despite having the multimedia haskell book.
[snip]
The take operator
Crypt Master [EMAIL PROTECTED] writes:
-- gaSolutionSpace :: [a] - [a]
gaSolutionSpace x = x : gaSolutionSpace (evolvepopulation x)
Stop deceiving yourself until it's too late. :)
Why did you comment out the type annotation?
--
Feri.
___
Ok Crypt Master give the hint to pronounce something ,because I feel a
complete stupid in front of Functional Programming' though I'm a trained
imperative one.
I've read the nice paper www.cs.chalmers.se/~rjmh/Papers/whyfp.html and
remember may years ago the hard job done to make my chess
1. Speed: I'm reading in a 2000x1500 pixel image, and have defined a
Pixel type like this:
data Pixel a = Pixel !a !a !a deriving Show
[with a==Float being a typical instantiation]
For images of this size, I'd recommend using a different datatype because:
1) Each Pixel Float will take
Alastair Reid writes:
[...]
Overall, I'd probably use an unboxed Haskell array. This would let you get a
memory layout (and memory consumption) close to the normal C layout. I'd use
access functions to hide the boxing/unboxing and I'd write some
map/fold/scan-like functions to
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