Comments on: Microbenchmarks: exec convert vs imagick

By: Imagick blog » Blog Archive » Microbenchmarks: exec convert vs imagick

Imagick blog » Blog Archive » Microbenchmarks: exec convert vs imagick — Fri, 15 Jan 2010 23:54:03 +0000

[...] is the script i used with Imagick: PLAIN TEXT [...]

By: Mikko Koppanen

Mikko Koppanen — Mon, 27 Jul 2009 15:59:59 +0000

dominik,

I thought “thumbnail” uses same algorithm in both since it’s not much more than a wrapper to resize. Quality level is also default in both (which i assume matches as well).

By: dominik

dominik — Mon, 27 Jul 2009 15:54:34 +0000

Nice try, but You missed several things:
+ algorithm (there is huge difference in both end-quality and time)
+ quality level (have You tried just to compare sizes)
Set those and You will get almost same time for both operation. Pay attention at cache etc. – they are sometimes tricky!

By: Mikko Koppanen

Mikko Koppanen — Sat, 08 Mar 2008 17:02:39 +0000

From Felix:

Just wanted to add that comment on http://valokuva.org/?p=40 but your wordpress seems not to want it

“For websites that deal with user generated images one thing is usually very common: Generating thumbnails from source images. Normally one would generate 3,5 or even 10 thumbnails per source image which we could dramatically speed up using Imagick. Instead of performing an exec() for each thumbnail to generate we now load the source image once into an Imagick object and do a “clone,thumbnailImage,cropImage,getImageBlob” sequence per thumbnail to generate. With that technique we have to load and decode the source image only once which gives us huge performance gains.”

By: Mikko Koppanen

Mikko Koppanen — Sun, 07 Oct 2007 19:39:15 +0000

You could propably easily benchmark plain convert vs php exec difference using a shell script like:

#!/bin/bash

for i in /path/to/images/*.jpg
do
convert -thumbnail 200 $i /tmp/th/`basename $i`
done

By: dsp

dsp — Sun, 07 Oct 2007 19:20:36 +0000

It’s pretty clear that the exec is slower. It exec call results in a syscall which forks the convert executable. I guess the extension uses a similar (maybe equal) library than convert. So the time difference is more or less the time needed to fork and context-switch the convert exectuable.

By: Mikko Koppanen

Mikko Koppanen — Sun, 07 Oct 2007 17:56:20 +0000

To be honest, Imagick does not honor PHP memory limits. The memory allocations are (currently) done outside the PHP mechanisms.

I also wrote about memory limiting earlier: http://valokuva.org/?p=11

I’ve tested memory usages with Imagick using external tools and noticed that peak memory usage is not much over the size of the images you’re reading in to the object.

By: Kae Verens

Kae Verens — Sun, 07 Oct 2007 17:50:37 +0000

I use the exec() ImageMagick method in my KFM project (http://kfm.verens.com/). One reason I use it is that built-in extensions suffer from the memory limitations that PHP imposes on them, whereas a shell command appears to be unconstrained.

It is interesting that the imagick extension is faster, but how does it compare for very large images in a limited memory environment?