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Re: FOR loops removal [message #62091 is a reply to message #61975]

Mon, 25 August 2008 01:31

loebasboy
Messages: 26
Registered: August 2008

Junior Member

On Aug 22, 8:19 pm, Chris <beaum...@ifa.hawaii.edu> wrote:
> Are you looping 139520 times because you have that many images you are
> reading from disk? If so, you probably aren't going to be able to do
> any better. I/O is unavoidably slow. If not, what are you doing that
> requires so my loops? How quickly do you process one image?
>
> As a general guideline, most image processing on a single image (say a
> few megapixels) should be on the order of a few seconds once
> vectorized well. If you have several hundred thousand images, one
> thing to consider is to merge them into larger files (by making data
> cubes). This would reduce the number of hard-disk seeks during IO.

There is only 1 image that is processed. 1 loop works on a part of the
image, that is, several columns and all the rows. When 1 loop is done,
all columns are moved up one column spot and at the end of the part a
new column is added (from the full image). The first column is then
removed from the part. And so the the full image is processed. 600
columns means 600 loops minus the width of the part two times. Also in
every loop the process is repeated 4 times.

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[Message index]

		FOR loops removal By: loebasboy on Tue, 19 August 2008 05:38
		Re: FOR loops removal By: loebasboy on Thu, 21 August 2008 07:27
		Re: FOR loops removal By: Jeremy Bailin on Thu, 21 August 2008 08:40
		Re: FOR loops removal By: Jeremy Bailin on Thu, 21 August 2008 06:39
		Re: FOR loops removal By: loebasboy on Thu, 21 August 2008 00:59
		Re: FOR loops removal By: Jeremy Bailin on Wed, 20 August 2008 07:07
		Re: FOR loops removal By: loebasboy on Wed, 20 August 2008 05:36
		Re: FOR loops removal By: David Fanning on Tue, 19 August 2008 13:14
		Re: FOR loops removal By: loebasboy on Mon, 25 August 2008 01:31
		Re: FOR loops removal By: Chris[6] on Fri, 22 August 2008 11:19
		Re: FOR loops removal By: ben.bighair on Fri, 22 August 2008 03:50
		Re: FOR loops removal By: loebasboy on Fri, 22 August 2008 02:08
		Re: FOR loops removal By: Chris[6] on Thu, 21 August 2008 11:34

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