JPEG graphics for large story images

scott · Post by **scott** » February 1st, 2005, 4:37 pm

I did a scan with omni disk sweeper, and I noticed our story images are large. 18 .pngs take up 6.6 MB out of approx 30 MB in resources. In order to get Liberty to upload to the forum (in the old days

) I had to convert the pngs to jpgs.

I converted the 5 biggest files and went from 2.3 MB down to 300k. Take a look and see if you can detect any loss in quality. I picked 85% quality as the lowest I could go before noticing sinc artifacts. The Green Isle picture ALREADY HAD filtering artifacts in png form, so I could have gone down to 50% but for the frame.

The best thing is that the HttT story pictures are already very blurred, and except for the frame these could easily go down to 40-50% before you notice anything. There's just no high frequency content in any of them. If there is positive response I will finish with the HttT pictures (at probably 65-75% quality for the frame's sake) and submit the set. If you could cut out 5 MB from the final product, I think it would be worth it to some people.

Edit: cut out some stuff that didn't apply and was wrong.

Post by **Jetrel** » February 1st, 2005, 5:14 pm

As long as there are no code/legal issues, I'm all for it.
I'd really like this to happen, just because it saves SO MUCH SPACE.

XJaPaN · Post by **XJaPaN** » February 1st, 2005, 8:40 pm

Good idea, the free space could be useful for future things to come.

charlieg · Post by **charlieg** » February 1st, 2005, 11:05 pm

XJaPaN wrote:Good idea, the free space could be useful for future things to come.

Especially in terms of web server load...

Invisible Philosopher · February 1st, 2005, 11:34 pm

I agree this would be good too.

Mkgego · Post by **Mkgego** » February 1st, 2005, 11:36 pm

Yeah scott! Why taking png images if jpg has the same quality and it take up many less kbs than png files !!!

scott · Post by **scott** » February 2nd, 2005, 7:25 am

The full set is available at http://www.cis.rit.edu/~slk8779/wesnoth ... ressed.zip

You be the judge.

Post by **ivanovic** » February 2nd, 2005, 9:34 am

Hi everyone!
I have taken a look at the picture. I tried to scale them a bit and found that the mission maps can get some probs when trying to scale them. Maybe it would make sense to leave at least this ones as they are. The story based images do scale very well and i can't really find a difference between the jpeg version and the png version. But beside i do NOT know how much problems it could make to implement another lib into the game. At the moment the game does not depend on the jpeg-lib. If jpeg-pictures would be integrated there would be another dependency.
But maybe the devs take a look at it and it is hopefully possible to include the support without too many probs.
CU
Nils Kneuper aka Ivanovic

Invisible Philosopher · February 2nd, 2005, 10:37 am

ivanovic wrote:Hi everyone!
I have taken a look at the picture. I tried to scale them a bit and found that the mission maps can get some probs when trying to scale them. Maybe it would make sense to leave at least this ones as they are. The story based images do scale very well and i can't really find a difference between the jpeg version and the png version.

Leave the original PNG available elsewhere.

ivanovic wrote:But beside i do NOT know how much problems it could make to implement another lib into the game. At the moment the game does not depend on the jpeg-lib. If jpeg-pictures would be integrated there would be another dependency.

SDL_Image can (and does) already handle JPEG. I use it in my campaign, as do others in theirs.

Post by **Jetrel** » February 2nd, 2005, 11:15 am

Invisible Philosopher wrote:
ivanovic wrote:Hi everyone!
I have taken a look at the picture. I tried to scale them a bit and found that the mission maps can get some probs when trying to scale them. Maybe it would make sense to leave at least this ones as they are. The story based images do scale very well and i can't really find a difference between the jpeg version and the png version.
Leave the original PNG available elsewhere.

he meant how we have many, many resolutions supported by wesnoth, and yet in all of them, the story screens fill the monitor (IIRC). Such scaling with a png looks fine, such scaling with a jpen can go to hell in a handbasket, do to the way it compresses stuff.

That said, this is starting to look rather promising.

Invisible Philosopher · February 2nd, 2005, 11:23 am

Jetryl wrote:he meant how we have many, many resolutions supported by wesnoth, and yet in all of them, the story screens fill the monitor (IIRC).

That is not true. I tested with lots of different wesnoth screen sizes to make sure. Wesnoth does *not* scale story images.

scott · Post by **scott** » February 2nd, 2005, 12:28 pm

Both jpeg and png are bitmap graphics. Once uncompressed, they should scale the same way, as far as I know. There isn't any more information in a displayed png than there is in a displayed jpeg. Jpeg compression cuts out contrast (quality) not resolution (quantity).

Ankka · Post by **Ankka** » February 2nd, 2005, 2:12 pm

Invisible Philosopher wrote:
Jetryl wrote:he meant how we have many, many resolutions supported by wesnoth, and yet in all of them, the story screens fill the monitor (IIRC).
That is not true. I tested with lots of different wesnoth screen sizes to make sure. Wesnoth does *not* scale story images.

Nor the game itself... the only thing I've noticed have been scaled is the minimap( or was it?) and the "observers"-sign in the up left corner in multiplayer... basicly everything else is the same as in full screen mode.

Elvish_Pillager · Post by **Elvish_Pillager** » February 2nd, 2005, 7:49 pm

Ankka wrote:That is not true. I tested with lots of different wesnoth screen sizes to make sure. Wesnoth does *not* scale story images.

Nor the game itself... the only thing I've noticed have been scaled is the minimap( or was it?) and the "observers"-sign in the up left corner in multiplayer... basicly everything else is the same as in full screen mode.[/quote]

It also scales the main display if you use the zoom in/out keys.

I find them more annoying than useful, and eliminated the hotkeys.

tuppe666 · Post by **tuppe666** » February 2nd, 2005, 9:06 pm

Just out of interest I ran AdvancePNG.

Code: Select all

 for i in *.png; do advpng -z4 "$i" ;done

Just to see what saving could be made leaving them png.

The images directory drops from 22419456 bytes to 21866496. Not to be sniffed at and nothing needs to change.

Code: Select all

find . -name '*.png' | while read i; do optipng -o7 "$i"; done

optipng drops it to 21632000 saving a meg nice