Very slow speed convertion

[gazzateo]

Hi everyone
I tried to convert some big images tif (more than 1 Gb 16bit of color depth) with convert command.
I want to rotate them 270° and to reduce them in only 8bit color depth.

When I tried it on Ubuntu 13.04 - 4Gb RAM, reading from an USB formatted in FAT32, writing in another USB in FAT32 and temppath set on a temp folder in internal HD - all goes right and all operations required less than 30 seconds per image.
But this was only a test; the real job has required reading from NTFS and (overall) writing on NTFS. So, during the real job, each convertion requires a bit less than 60 seconds. [edited: I've done a big mistake - not 60 minutes, but 60 seconds!!!)

So I think I can try this conv on Windows: I mean that Win7 it's not so time-expensive writing NTFS than Ubuntu.
Result: same machine, booted on Win7: little more than 15 minutes each convertion.
I don't know why this incredible difference between the two OS.
Is there anyone that has ever detected this?

Thank you!

[gazzateo]

I'm thinking about some different configuration between imagemagick for Linux and for Win.
I'm thinking something like a default configuration more optimized on Linux.
Am I wrong?

Please someone help me!

[snibgo]

What version of IM are you using on each system?

How many pixels in your image? If this is (P), you probably need (P*6) bytes of memory. Ubuntu may use less memory than Windows, leaving more available to IM. You may be at a tipping point in running out of memory. The option "-debug cache" might indicate this.

See http://www.imagemagick.org/script/architecture.php for insights.

[gazzateo]

The image is 17310 x 11310 pixel, 16 bit per channel of depth-color.
I mean I have enough memory.
I have 4 Gb of RAM, and, where I stop some running not-so-useful processes, I think my PC could also make no swap on HD.
What I see is that the PC works to read image - from an external usb drive - than it start to write something on HD.
I've tried to set the temp path on C:\Temp or in C:\users\myuser\Temp, but both time no temp file goes there.
Finally, long long long after, it writes the output image on another external device.

My version is:

Code: Select all

Version: ImageMagick 6.8.5-10 2013-06-01 Q16 http://www.imagemagick.org
Copyright: Copyright (C) 1999-2013 ImageMagick Studio LLC
Features: DPC OpenMP
Delegates: bzlib fontconfig freetype jng jp2 jpeg lcms lzma png ps tiff x xml zl
ib

Now I try to use "-debug cache", as you advise.