PNGout

[Drahken]

The recent update to irfan has a new plugin that allows for excellent compression of PNG images. Apparently PNGout has existed as a prog for a while, but was only recently made into a plugin for irfan (or any other prog), here's PNGoput's homepage: http://advsys.net/ken/utils.htm I have found that this plugin is highly effective and results in distinctly smaller files. In fact, it even changes the old rule that gifs get better sizes than PNGs on tiny images. With PNGout, PNGs are always smaller than gifs. I think Xnview could benefit greatly from this tool.

Here's a comparison with a simple image:

Irfan (without PNGout), 2,164 bytes


Xnview, 1,943 bytes


PNGout, 1,213 bytes


...and just for comparison: GIF, 2,084 bytes

[helmut]

Thank you Drahken for pointing to PNGout.

All compression types used above are lossless (except of colour for GIF), so comparing the images results in finding no difference - right? So PNGout with 1.2 KB only really does a good job.

Not sure on which technical level the integration of PNGout can be done, but it's surely interesting and should be followed up by Pierre. Likely this will not happen in 1.80, but later.

[Drahken]

Yep, except for the filesize, all the above images are identical to each other.

I see on the site that there are currently 3 versions of PNGout, a windows exe, a linux exe, and the irfan plugin. It doesn't look like Ken Silverman releases the source to PNGout, but it does look like he's willing to make ports and plugins of it for people. Perhaps he'd make a plugin for Xnview if asked him. Alternatively, would it be possible to adapt the irfan plugin? I don't know exactly how irfan and Xnview plugins differ.

[Drahken]

1016 1111
I just ran a test making a PNG with Xnview, then using the PNGout standalone prog to compress it further:

XNview: 1,111 bytes.


PNGout recompressed: 1,016 bytes (nearly a 10% savings).

[helmut]

Drahken, pngout is really good. I've made some conversions using it, and it typically squeezes 10-15% out of any png. Especially when using larger graphics in internet, size is important, here pngout is really helpful and valuable. The conversion takes a bit on larger images, but better wait once and all visitors wait less.

An important thing to know about the PNG format is that it supports both True Color images and palette images. If your image needs only few different colours (<=256), make sure you convert it to a palette image (Image > Convert to colours), save it, and then run pngout on it. See also FAQ "What format should I save this image in?".

[ladiko [not activated :'(]

will pngout ever be a plugin of xnview

p.s.:
i dont get the email to activate my account "ladiko"
maybe a admin could resend it? i dont find where to get it myself - cause "forget my password" doesnt help and the rest is french et mon francaise est ne pas très bien, seulemente en peut que je apprend sur l'école

[xnview]

will pngout ever be a plugin of xnview

I've contacted the author, now i wait...

p.s.:
i dont get the email to activate my account "ladiko"
maybe a admin could resend it? i dont find where to get it myself - cause "forget my password" doesnt help and the rest is french et mon francaise est ne pas très bien, seulemente en peut que je apprend sur l'école

please contact me by email

[Hobbe]

1016 1111
I just ran a test making a PNG with Xnview, then using the PNGout standalone prog to compress it further:

XNview: 1,111 bytes.


PNGout recompressed: 1,016 bytes (nearly a 10% savings).

The original gif image has 45 colors, these 2 have 16, no wonder why they're smaller...

Now beat this



1.17 KB (1,207 bytes)
45 colors.

[Danny]

AFAI understand, pngout just tries out all (9?) different compression methods and chooses the one that does it best. Currently you can do that manually in XNview.

Correct me, if i'm wrong.

[Drahken]

It does more than that. Make a PNG wih xnview using any filter/settings you want, run it through pngout and you'll find it much smaller. 2 drawbacks to pngout are that it only works on indexed (256 color) png, and it takes a while to compress the pic.

[helmut]

p.s.:i dont get the email to activate my account "ladiko"
maybe a admin could resend it? i dont find where to get it myself - cause "forget my password" doesnt help and the rest is french et mon francaise est ne pas très bien, seulemente en peut que je apprend sur l'école

ladiko, your account should be active, now. Please let the admin know if this is not the case.

[Danny]

It does more than that. Make a PNG wih xnview using any filter/settings you want, run it through pngout and you'll find it much smaller. 2 drawbacks to pngout are that it only works on indexed (256 color) png, and it takes a while to compress the pic.

How does that disagree with what i wrote?

[Olivier_G]

How does that disagree with what i wrote?

You suggested that one could try and manually select the best Compression method in XnView... while Drahken precised that PNGOut would always provide a much smaller result than this suggestion.
So, it's different (although I don't know how PNGOut exactly works).

[Drahken]

More info: http://advsys.net/ken/util/pngout.htm Pngout automatically chooses the best filter, can use different filters with each pass (other programs can only use the same filter with each and every pass), it automatically chooses the best color type (indexed, truecolor, greyscale, etc) and the best number of colors, remove extra chunks, split blocks at different sizes, and some other things. All you can do with most progs (including xnview) is choose color depth and a single filter to be used for all passes. Additionally, pngout does all of this automatically, whereas you would have to run litterally dozens of experiments on each image to even try to get similar results (which you would never be able to achieve).

Really, all this info is available from the link in my first post.....

[Clo]

—> Drahken


Hello !

• Just a hitch : I can't get the ZIP from http://ardfry.com/pngoutwin/, I have an "Access denied - 403 -" error…

KR
Claude
Clo