Help:Background images

Background images are those image files which appear literally in the background of this and every page on this wiki. The bulk of these images are seen outside the page margins, but in reality the image extends underneath the entire page. If you look carefully, you can probably see that the image is dimly visible underneath the page. This unusual behaviour means that images proposed for our background must be prepared in a special way. This tutorial will first explain how the background image works, and then provide an explanation of how these images should be prepared by the user.

How backgrounds work here
Our wiki uses a special bit of CSS coding to ensure a couple of interesting dynamics.

First, as already discussed, there is a distinct difference between the visibility of the image outside the page margin and the way it appears underneath the page. This is achieved by covering the entirety of the page with a translucent white background that sits between the page and the background image. Effectively, we've put a thin "screening layer" in front of the background image. This improves readability of the foreground text, while also allowing the background image to offer subtle texturing.

Second, the picture remains in the same position, no matter how far down you scroll. If you'd like to see the difference between our page and that of the typical Wikia wiki, go to starwars:Yoda and scroll down. You'll note that their top-border image of Coruscant disappears when you scroll down the page. Our backgrounds, by contrast, stay put.

What this means is this eliminates the need to do tiled backgrounds (they're seen on many other wikis) and instead allows us to create a single, unrepeated background that appears as a strip at the top of the page. It also gives us the flexibility to make something longer, if we choose. In essence, the page fits our design, not the other way around.

Parts of the page
In order to understand how to make a background, we must first examine a page in detail. To aid that understanding a special "test background" was created. It should not be taken as an artistic example, but rather a design which helps us define the parts of the page more readily.

File format
Background images must be in PNG format. It's the only allowed format. Background images must contain transparent elements, and the PNG format is the only transparency-enabled format which wikia allows for backgrounds. Unfortunately, if you do not have software which allows you to create PNG files, you cannot submit backgrounds to our wiki.

File size
Wikia restricts the size of the file to 100kb. Please try to submit files which are less than this. If you find, however, that you just can't make it work, go ahead and submit it, as long as it's in the PNG format. We may be able to compress it or crop it, or put it into a different variety of PNG. Still it is preferred that you present us with a file that we can use without alteration.

Transparency required
Your images must be on fully transparent backgrounds. Any submissions on a coloured background, even a white one, will be rejected. The background image must blend into the background colour, and the only way to do this is if your image is on a transparent background. Furthermore, the image itself must be a minimum of 75% transparent. Note that with the Yeti in the above screenshot, we can actually partially see through them to the background grey underneath.

The reason for all this transparency is to make sure that your design does not prevent article text from being read.

Tiling discouraged
We want designs which run the width of the page, once. An obvious design would be to make a single TARDIS roundel and then tile it across the background; we're looking for stuff that's a bit more imaginative. Unless the tiling produces something unexpected, please don't submit it.

Colour discouraged
This might seem like a weird one, but it's vital. Colour images underneath a page make the text hard to read. Since background images tend to hang out underneath the parts of articles traditionally given over to infoboxes, this can cause a big clash. Colour is therefore discouraged, though it might be allowed if it's not too busy and it's no less than 50% transparent.

Feather the bottom edge
Unless your design is round, chances are you'll end up with a hard edge that we don't want. Note that the Yeti example makes this mistake deliberately for illustrative purposes. Our Yeti therefore look ridiculous, frankly — more like Cookie Monster hand puppets than menacing Yeti. What we need is a way to "fudge" the bottom edge so that it doesn't look like we just cut the photo out with a pair of scissors.

Hence what's known as "feathering". It's where you blend a top layer into a bottom one, eliminating a hard edge. This can be done a number of ways — some versions of Photoshop make this very easy indeed. Plenty of tutorials on how to do this trick are available at the end of a simple Google search. Here's a simple example of feathering. Note that this tutorial shows how to feather an image on all sides to a black background. What we want is an image that's only feathered in one direction, down, and to the colour of #B0B0B0. To do this, follow the instructions as given in the linked tutorial, but choose a selection area that concentrates only on the bottom edge of the design.

How to make and submit a background
The following instructions assume that you have a working knowledge of photo manipulation software, and shall likely use terminology that's Photoshop-centric. If you're not that familiar with photo-editing, you may require more individual instruction. Click here to ask a question.
 * 1) Make sure that your preferences are set to measure in terms of pixels and that guide lines and rulers are enabled. (Generally guide lines default enabled. To test put your mouse on one of the two rulers. Click with your left mouse button. Drag away from the ruler. If a line, by default blue, follows you around, your guides are enabled. If not, check your preferences.)
 * 2) Start a new image
 * 3) Make sure the image has a transparent background (usually a check box in the "new image" window)
 * 4) Make the width 1500px
 * 5) Make the height whatever you want it to be, but preferably no less than 200px and no more than, say, 1000px. The Yeti example uses 400px, which keeps the images in the upper third of the page.
 * 6) You then need to set up some guide lines. Pull down a horizontal guide from the top of your image to the 50px mark. This guide stands for the wikia header. None of your image should be above this top line. Now you need to place vertical guides at 250px and 1250px. This means that the distance between your left and right guides is 1000px, the size of a Wikia page.
 * 7) Create your design, aware of these guides.
 * 8) Make sure that the layers which contain your images are no less than 75% transparent. In Photoshop, this is easily done by selecting the appropriate layer on the layer palette and then just fiddling with the opacity slider.
 * 9) When you're happy with the design, you need to choose to do what Adobe calls "save for web". Other companies might call it "image compression", "web compression" or something of that ilk. It's essentially a compressed way of saving. You'll never make it to the tiny 100kb size limit if you just save the file normally. In Photoshop, at least, there's then an option to choose between a couple of formats of PNG. As you fiddle with it, you'll be able to see in the bottom left-hand corner of the window an indicator of how bit the file is. You just have to keep whittling away at the quality of the file until you get to 100kb. If you play with it for a while and you still can't get it under 100kb, even at the lowest quality, you may have consider cropping your image. If you've got a 400px image, consider going to 300px. If you have an image like this Yeti thing, where you've essentially got transparent space on the extreme left and right, then reducing the width to 1400 isn't going to hurt anything. If you've gone against recommendations and made a colour design, going monochromatic will reduce file size (another reason why colour is discouraged). Hitting that 100mb limit with the PMG format is pretty hard and it may take you a while to figure out how to do it.
 * 10) Upload your finished PNG file to the wiki, and place it at Tardis:Background image submissions in the appropriate category.

Rules governing submissions
As with everything on the wiki, you agree that your work is governed by CC-BY-SA. Once submitted, there is no legal opportunity to withdraw it or protect it to any significant degree. You agree that other users have the right to remix your work.

Most importantly, by submitting your design, you agree to make available all files you used to create the design to any admin who asks for them. This is because only admin have the power to actually put a background design up on the site. And it's extremely unlikely that your design will work "out of the box". Its transparency levels will almost certainly have to be fiddled with, and it's a lot easier to do this with your raw Photoshop files, for instance, than it is to take a finished PNG file, reverse engineer it, break it down into its constituent layers, and try to recreate an editable file.