just guessing but they are usually zip files that contain more than one image, they contain (usually) several images made at various resolutions.

Yes you need normal resolutions including the 4:9 , 16:9 
I did that in the begining but im not going to do so anymore i only know  view folks that still run a 4:9 screen

Also you may need to make a zip if you want to upload a PNG, in windows8 jpeg and BMP get downsampled - i noticed that when i applied some of my photos as wallpaper - the solution is to use a PNG or a third party wallpaper prog. to prevent windows8 from doing so.
If you use JPEG or BMP the picture will be pixelated
So if you upload you should include a PNG for me prefered size HD1080 or 4k hehe
 

Windows8 does and this is a fact believe it or not will use a low res version of your wallpaper as background 
http://superuser.com/questions/507097/stop-windows-8-from-converting-wallpapers-to-low-quality-jpgs

I noticed this right on the release of windows8 when i applied the CHIP wall of mine to my windows8 desk
You may not see it, on every wall since sometimes its very hard to spot
But you will find enough topics about this on the www Andy
Sometimes its hard to spot and most people simply do not notice but it is happening prob even on your rig.

A example : http://superuser.com/questions/507097/stop-windows-8-from-converting-wallpapers-to-low-quality-jpgs
 
 or here http://www.eightforums.com/customization/5399-windows-degrades-desktop-background-images-2.html

This is also the reason why i will include a PNG from now on.


Just tried with your wallpaper take a look for yourself

Left windows8 wall - right screen original 

 

No pixel fuzz here either.Was hoping some of my earlier submissions did not suck, but , appears they did. Unless any Stardock staff has a guidline or rule I should follow.If so, please advise me, thanks everyone.Always free good advice in the nuthouse.

PS, screw windows 8!I use 7.Others have millions of other walls to use, they do not need mine.

That image looks like an effect to me, just zoomed way in , are you running high res.?Irun at 1680x1050,looks okay here.

Same here, Windows 8 Pro MC Edition. No pixelation, no fuzzyness, looks as fine as on Windows 7.

Roloccolor, ya can't believe everything you read.

JPEGs and BMPs work just fine. Assuming the wall was made well to begin with.

In reply 4, it looks like you are comparing a wall used on the desktop, to a wall shown in a browser. Not a great comparison.

I'm using Win 8 Pro......downloaded the same wall and set as my desktop, it does artifact(fuzzyness), same as Rolocolors left image......loaded it into PS and saved as a png and the artifacts are gone when set as desktop.....

There does appear to be a problem in the way Win 8 displays low res jpg images on the desktop......

Odd, I did the same with my own wall, 1920 x 1080, and I see no difference.

How are you setting the wall? By right click/set as desktop background? Or by way of personalize? vStyler used to say that it made a difference too.

Well, duh. I was applying walls with Display Fusion.          If I apply the wall with personalize, the png does look crisper than the jpeg. Hmm..

Yeah- the way i did it is not 100% accurate i would have needed to zoom in the browser*1 or make a png under the supervision of a Prof.Dr. that takes care that i do not mess up the process of converting a delicate jpg file into a png... after that is finished i would need to make 2 screenshots or tell windows8 to use one for the first monitor and the jpg for the second- but im lazy therefore the browser did just fine to show the difference, after all im not writing an exam here just trying to explain that down sampling does happen and as long as I got you to test it for yourself my mission is a success.  

If anyone is already running 8.1, it would be nice to know if they fixed that  

s0 PNG it is. Thanks all,you rock.DT1

doortech1 you can include a png, for folks on windows8
but people on windows7 will of course use the lot lighter jpeg.
So if you upload a wallpaper these days include the standart sizes up to 1080p
and if you like add a single PNG and name it windows8 or *name*_win8.png

 

Thanks Roloccolor.

You're welcome!

sorry to be a little late for this but....

generally png's retain their color edges/integrity while jpg's bleed into the surrounding pixels. As far as which to use, that depends on the effect one is attempting to attain. I have saved files as a jpg to get that cross pixelation, then open and save the resultant image to a png for use in a windowblind.

it's an experiment.

None meant....lol.   

Apparently, you can believe SOME stuff you read.