High quality image resizing @ Jaguar

[hip]

Hi,

I'm making use of GD to create thumbnails on-the-fly from bigger images uploaded through an HTML form. I'm using a prefab php class that acts with GD, and have everything installed in my server space at Aletia (Jaguar). Everything works ok, but image quality for the thumbs is pretty low.

Large images have a 70% quality jpg compresion. I've tried both, 70 and 95 for the thumbs, but compressed image quality is still low. I've googled for it and found out everybody agrees that GD compresion quality is low if compared to Imagemagik and Netpbm, for instance.

My question: May I use Imagemagik or other graphic module within this host? Are they (the modules) already installed or may I install them?

[ not having root access, I may need modules (may they be PHP, Perl,...) * I only need thumbnail creation (though more capabilities may be interesting for future projects) * I may ask the Tech Support but prefer to have some real cases information beforehand]

Thanx in advance for any info,
hip

[Rye Seronie Oh]

Imagemagick can be used: /usr/local/bin/convert (on my server, atom) If that's not your path, try using "whereis convert" on your shell and it will tell you where it is. I don't know if there are any other image conversion tools on there..

[hip]

Thanx Rye,

Ok, I'll give it a try, but it'll be tomorrow, for I'm already done today, and still have some code to do. As soon as I find the path I'll try to manage with Imagemagik (I've never used it before), google a bit for it, check their site and, probably, come back for some extra advice.

No news will mean good news. ;-)

Thanx again,
hip

[jason]

Netpbm is also installed on at least some of the servers, although I've never used it no do I know how.

Another thing to check: if your script is kind of old, it might be using the older imagecreate() and imagecopyresized() functions. Changing them to imagecreatetruecolor() and imagecopyresampled() will allow you to resize images using a much larger color palette (millions of colors vs. 256), which will result in much higher quality thumbnails. The new functions are part of GD versions 2.0+, which should be fully supported on JPC servers these days.

--Jason

[Vin DSL]

Sorry! I don't have the time or patience to read this whole thread...

However, 'GD' blows! Use 'Image Magick'

On 'my' server, the path I use is ' /usr/bin/X11/mogrify'

Sheesh, hold on. I haven't checked it for a while...

bash-2.05a$ whereis mogrify
mogrify: /usr/bin/mogrify /usr/X11R6/bin/mogrify /usr/bin/X11/mogrify /usr/local/bin/mogrify /usr/man/man1/mogrify.1

Your choice...

[DLMunson]

heh really? i use phpnuke port of coppermine, and it defaulted to GD2.0 ....i guess ill switch to imagemagick and try it out...hmm

[gerilya]

GD library is perfectly capable of producing high quality thumbnails.
The attached thumbnail was produced by GD library. Original image is also provided for comparison.

[Ron]

I switched coppermine over to ImageMagick and my thumbnail size went from usually under 6k to around 30k. I switched back.

[Spathiphyllum]

One might also need to evaluate performance and not just image quality. ImageMagick might be too heavy duty for most needs and less likely to be resident in memory since more people use GD. Image Magick, from my brief experience, is a good tool in that it has many filtering tools... but at the cost I mentioned. If it needs to be loaded into RAM, there's going to be a delay. I've not benchmarked the difference but just observed it anecdotally. Not very scientific but something to be considered.

[Ron]

It seemed speedy enough, and there's probably a setting somewhere to tell it to reduce the quality/filesize on the thumbnails, but "crikey"! 33K for a thumbnail is just way, way too high.

[Connie]

It seemed speedy enough, and there's probably a setting somewhere to tell it to reduce the quality/filesize on the thumbnails, but "crikey"! 33K for a thumbnail is just way, way too high.

Ron have to agree with that. I try to keep all pages under 20 KB. I'm on a slow dial up an a lot of Internet users are. If the page does not load in 15 to 20 seconds the user will probably hit the back button.

[Vin DSL]

If the page does not load in 15 to 20 seconds the user will probably hit the back button.

You could always defeat the back button...

[Vin DSL]

I switched coppermine over to ImageMagick and my thumbnail size went from usually under 6k to around 30k. I switched back.

Aha! Check this out, Ron...

I've been experimenting with Menalto Gallery 2 (my wife's standalone photo gallery - not for PHP-Nuke) and ran across this thread.

http://gallery.menalto.com/index.php...&postorder=asc

Read better the lines, my man! +profile "*" seems to be the key...

[Vin DSL]

To convert a directory full of JPEG images to thumbnails, use:

mogrify -size 120x120 -resize 120x120 +profile "*" *.jpg

In this example, '-size 120x120' gives a hint to the JPEG decoder that the images are going to be downscaled to 120x120, allowing it to run faster by avoiding returning full-resolution images to ImageMagick for the subsequent resizing operation. The '-resize 120x120' specifies the desired dimensions of the output images. It will be scaled so its largest dimension is 120 pixels. The '+profile "*"' removes any ICM, EXIF, IPTC, or other profiles that might be present in the input and aren't needed in the thumbnails.

SOURCE: http://maconlinux.net/linux-man-pages/en/mogrify.1.html

[Ron]

I guess that would require me to crawl through the source , find where the directives are constructed and modify it, then test it a bunch of ways to Sunday.

I think I'll stick with the GD lib ! Seems to be working ok. I've got about 900 user entries so far, I think.

Thanks for keeping me in mind though!