XnView Software

Recently I am using large 8-bit PNG files ,
crooping them and then saving back to PNG format.
The files are about 25 MB large on disk (unpacked 88 MB) .
Loading the PNG takes some 10 sec. , but when I save this file it takes 4 1/2 minute, with full (single core) processor load of a core-2 duo processor.

Curious as I am I did the same test with Photoshop CS4, loading goes with the same speed,
when I save the file in PNG format CS4 uses the 2 cores of my Core-2 duo processor fully,
but yet it takes a full 13 1/2 (!) minute to complete.

I am glad that XnVIEW is about 3 times as fast , but still it takes a very long time,
what is going on here ?? , and is there room for optimization ?

By the way: are there any processes (loading,saving,manipulating data, ... )
where XnView uses all cores of a multi-core processor, or is it only single core ?

René


EDIT: doing the same test with Paint Shop Pro (version 7.02) gives me an even faster write: 66 secs , that should be our target !!

Maybe Photoshop and the others programs aren't using maximum compression + preprocessing filters thus taking less time to complete.

you are right, it had to do with the compression-factor,
in XnVIEW the compression can be set from 0 to 9;
I did a quick check with these 10 settings:

compr.; time (s) ; size (MB)
0 ; 38 ; 89.9
1 ; 19 ; 31.8
2 ; 20 ; 30.8
3 ; 22 ; 29.5
4 ; 23 ; 27.3
5 ; 28 ; 27.2
6 ; 46 ; 26.9
7 ; 65 ; 26.5
8 ; 230 ; 25.8
9 ; 270 ; 25.5

There is a big difference both in time and size, but for me a compression-setting of 4 would be good enough with a, acceptable file-size and compression-time

René

A related discussion:
•PNG compression levels

rra wrote: where XnView uses all cores of a multi-core processor, or is it only single core ?

XnView use only 1 core

Ah...!!!

Now there is a reason for an XnView "2.0": multi-core!

JohnFredC wrote: Now there is a reason for an XnView "2.0": multi-core!

After XnViewMP release, i'll work on multi core with XnViewMP (i've already made some tests)

Good news again Pierre,
will this MP version also support 64 bit ??

René

rra wrote:Good news again Pierre,
will this MP version also support 64 bit ??

XnViewMP will have win, linux & mac 32 & 64bits version