I am have created a background image in photoshop but would like to know what size the image be? Length + width. I am using the image as the background behind the table so it looks as if the table is floating on top of the image. I have created one that was 22" by 15" but I know that there has to be another way due to all the different monitor sizes out there. What is the standard and how is it accomplished?
Go to New and create a document that is 72 pixels/inch, 1440 pixels wide and 900 pixels tall.
Hmm.... so by "background," do you mean that you're creating desktop wallpaper? If so, the perfect size for the wallpaper is the resolution of your desktop. You can find out what your own resolution is, or just google wallpaper downloads, and you'll find a lot of common sizes are offered. (1440x900 is a very reasonable size that's fine for most people, unless they are these people at lifehacker--read some of the comments--who find that size laughable. )
"As the background behind the table"... --AHA!!! You're creating something for the web! If that's the case, then again, there is no "standard" size. You'll have to experiment and look around the web until you get a sense. For example, the white "content" area of this very webpage looks to be about 1000 pixels wide. The blue area, or background, is flexible to the size of the window. (So 1440x900 pixels is a perfectly fine place to begin.)
Bear in mind that it's meaningless or at best confusing to talk about "inches" unless you're designing for print media. For the most part, computers care how many pixels wide something is. The resolution, or pixels/inch value, is just a sort of tag telling the computer what size and resolution to print the document if you ever were to print it. Even then you can print it at whatever size you want, the computer just uses pixels/inch as a starting point. Some programs do use this metadata, that's why it's a good idea to keep everything 72 pixels/inch (standard resolution for web and screen graphics.) This way also you'll have a sense of how big your designs really are.
I have a the link to a website that uses the type of background I am interested in. The table floats above the background image. If I am understanding correctly the suggestion being made is design my background image at 1440 pixels by 900 pixels in say Photshop and that size should be sufficient for most.
Below is a link to the type of background I am referring to.
Failing that--say to get the size of an embedded flash, or an image that's been published in different slices--you can look at the page source, or on a mac CMD-CTRL-SHIFT-4 to screen grab the image and then paste it into a new photoshop document, and you can tell its size.
There is no specific dimensions I can recommend in your case since it seems like your table width will change with the browser viewport.
You can either have an background image that tiles to fill the entire space covered by the table or create an image as wide as the maximum with you think the table can get.
It's best to consider a fixed width table so you can have a set of numbers to work with
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