Legacy ImageMagick Discussions Archive

I am using Arch Linux, and after the last upgrade the resizing with mogrify / convert became extremly slow: more than 10 seconds/image (720x540=>266x192). Before it was quick enough, a few seconds per / 70 images. What can I do to make it work faster again?

Not enough information.

What do you get from

convert -version

Do you have OpenMP or OpenCV installed? Are you using Q16, Q8 or HDRI?

Does your image have large amounts of meta data such as large profiles?

Can you post a link to your image?

What input format? What output format? Any compression?

If I run this it returns very fast for this 640x480 image on my Mac Mini running 1 thread and IM 6.8.9.8 Q16?

real 0m0.441s
user 0m0.042s
sys 0m0.014s


What times do you get from this same command?

On my VPS:
real 0m15.258s
user 0m14.197s
sys 0m0.893s

On my home machine:
real 0m45.332s
user 0m47.323s
sys 0m2.580s

My images are simple video screenshots, 720x540, 640x480 resolution. Simple jpg images, no metadata, they were extracted from videos by ffmpeg with quality "2".

My input format is .jpg, output format is plain .bmp (for faster processing).

try compiling without OpenMP and without HDRI and see if that helps. I have heard that onn some Unix systems OpenMP can cause a slowdown.

Are you sure that your input image has no profiles? What do you get from identify -verbose on your input file? Are you running an old version of libjpeg? Quality 2 is very low, though I would not expect that to be a problem. Try having ffmpeg output a larger quality. Are you extracting frames from ffmpeg or doing a screen capture while running the video?

If I compile from source with option:
Resizing works quick again. However command "montage" refuse to work.

fmw42 wrote:try compiling without OpenMP and without HDRI and see if that helps. I have heard that onn some Unix systems OpenMP can cause a slowdown.

Are you sure that your input image has no profiles? What do you get from identify -verbose on your input file? Are you running an old version of libjpeg? Quality 2 is very low, though I would not expect that to be a problem. Try having ffmpeg output a larger quality. Are you extracting frames from ffmpeg or doing a screen capture while running the video?

Quality "2" refers to ffmpeg command option, and it is higher quality than 4, 8 etc. Not imagemagick quality settings, I usually use quality 96 with imagemagick.

Resizing works quick again. However command "montage" refuse to work.

OpenMP should have no bearing on whether montage works or not. Sounds like a bad compile. Look in the config.log file for errors.

Other than this, I am not sure I can help with getting montage to work. Try a new compile. Try doing make clean before make.

If that fails, then recompile with OpenMP enabled again and try using thread control on the command lines that are slowed down. See

viewtopic.php?f=2&t=20756&p=83407&hilit=thread#p83407

Thx, it works now flawlessly and quick. I had to use a few other options to ./configure, because I doesn't have X installed on my VPS. (--with-freetype=yes, --without-x)